@article{
 title = {pi bonding},
 type = {article},
 year = {2020},
 id = {ce719109-6b4b-3b42-9400-a122f0ae0211},
 created = {2020-04-28T21:44:39.404Z},
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 folder_uuids = {ebbabfbd-939b-434c-8a89-bba932203a0b},
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 bibtype = {article},
 author = {Kellett, Cameron W. and Kennepohl, Pierre and Berlinguette, Curtis P},
 journal = {Nature Communications}
}

@article{
 title = {Regiocontrolled and Stereoselective Syntheses of Tetrahydrophthalazine Derivatives using Radical Cyclizations},
 type = {article},
 year = {2019},
 keywords = {Computational},
 pages = {976-980},
 volume = {25},
 websites = {http://doi.wiley.com/10.1002/chem.201805249,https://onlinelibrary.wiley.com/doi/abs/10.1002/chem.201805249},
 month = {12},
 publisher = {John Wiley & Sons, Ltd},
 day = {12},
 id = {467b698e-ca22-35da-b304-58e5023f365c},
 created = {2018-12-15T01:00:19.191Z},
 accessed = {2018-12-14},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:12.362Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 bibtype = {article},
 author = {Zhang, Wei and Mo, Jia Yi and He, Weiying and Kennepohl, Pierre and Sammis, Glenn Martin},
 doi = {10.1002/chem.201805249},
 journal = {Chemistry – A European Journal}
}

@article{
 title = {Anthracene as a Launchpad for a Phosphinidene Sulfide and for Generation of a Phosphorus–Sulfur Material Having the Composition P 2 S, a Vulcanized Red Phosphorus That Is Yellow},
 type = {article},
 year = {2019},
 pages = {431-440},
 volume = {141},
 websites = {http://pubs.acs.org/doi/10.1021/jacs.8b10775},
 month = {1},
 publisher = {American Chemical Society},
 day = {9},
 id = {fd714c41-09bb-3b53-aac2-8520ad81d239},
 created = {2018-12-15T01:00:19.202Z},
 accessed = {2018-12-14},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:12.700Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 abstract = {Thermolysis of a pair of dibenzo-7-phosphanorbornadiene compounds is shown to lead to differing behaviors: phosphinidene sulfide release and formation of amorphous P2S. These compounds, tBuP(S)A (1, A = C14H10 or anthracene; 59% isol. yield) and HP(S)A (2; 63%), are available through thionation of tBuPA and the new secondary phosphine HPA (5), which is prepared from Me2NPA in 50% yield by reaction with DIBAL-H. Phosphinidene sulfide [tBuP=S] transfer is shown to proceed efficiently from 1 to 1,3-dimethyl-2,3-butadiene to form Diels-Alder product 3 with a zero order dependence on diene. Platinum complex (Ph3P)2Pt(η2-tBuPS) (4, 47%) is also accessed from 1 and structurally characterized. In contrast, heating parent species 2 (3 h, 135 °C) under vacuum instead produces an insoluble and nonvolatile yellow residual material 6 of composition P2S that displays semiconductor properties with an optical band gap of 2.4 eV. The P2S material obtained in this manner from molecular precursor HP(S)A, shown by X-ray crys...},
 bibtype = {article},
 author = {Transue, Wesley J. and Nava, Matthew and Terban, Maxwell W. and Yang, Jing and Greenberg, Matthew W. and Wu, Gang and Foreman, Elizabeth S. and Mustoe, Chantal L. and Kennepohl, Pierre and Owen, Jonathan S. and Billinge, Simon J. L. and Kulik, Heather J. and Cummins, Christopher C.},
 doi = {10.1021/jacs.8b10775},
 journal = {Journal of the American Chemical Society},
 number = {1},
 keywords = {SSRL,X-ray Absorption Spectroscopy}
}

Thermolysis of a pair of dibenzo-7-phosphanorbornadiene compounds is shown to lead to differing behaviors: phosphinidene sulfide release and formation of amorphous P2S. These compounds, tBuP(S)A (1, A = C14H10 or anthracene; 59% isol. yield) and HP(S)A (2; 63%), are available through thionation of tBuPA and the new secondary phosphine HPA (5), which is prepared from Me2NPA in 50% yield by reaction with DIBAL-H. Phosphinidene sulfide [tBuP=S] transfer is shown to proceed efficiently from 1 to 1,3-dimethyl-2,3-butadiene to form Diels-Alder product 3 with a zero order dependence on diene. Platinum complex (Ph3P)2Pt(η2-tBuPS) (4, 47%) is also accessed from 1 and structurally characterized. In contrast, heating parent species 2 (3 h, 135 °C) under vacuum instead produces an insoluble and nonvolatile yellow residual material 6 of composition P2S that displays semiconductor properties with an optical band gap of 2.4 eV. The P2S material obtained in this manner from molecular precursor HP(S)A, shown by X-ray crys...

@article{
 title = {The Importance of Ligand-Induced Backdonation in the Stabilization of Square Planar d 10 Nickel π-Complexes},
 type = {article},
 year = {2019},
 keywords = {Organometallic Chemistry,SSRL,X-ray Absorption Spectroscopy},
 pages = {5259-5268},
 volume = {25},
 websites = {http://doi.org/10.1002/chem.201805987},
 id = {e61f6c06-b43c-3e83-ab9e-e53b3798e49b},
 created = {2019-05-15T23:05:41.114Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:18.234Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 folder_uuids = {ebbabfbd-939b-434c-8a89-bba932203a0b},
 private_publication = {false},
 abstract = {Ni π-complexes are widely postulated as intermediates in organometallic chemistry. However, the nature of the bonding in such complexes has not been extensively studied. Herein, we probe the geometric and electronic structure of a series of nickel π-complexes using a combination of 31P NMR, Ni K-edge XAS, Ni Kβ XES, and supporting density-functional computations. These complexes are best described as square planar d10 complexes with π-backbonding acting as the dominant factor in the M-L bond to the π ligand. The degree of backbonding correlates with both 2JPP and the energy of the clearly observable Ni 1s→4pz pre-edge transition in the Ni K-edge XAS data. The degree of backbonding is determined by the energy of the π*ip ligand acceptor orbital: unactivated olefinic ligands tend to be poor π-acids whereas ketones, aldehydes, and esters allow for greater backbonding. The strength of the backbonding from the neutral Ni(dtbpe) molecular fragment is dramatically increased via σ donation from the diphosphine ligands. In fact, in unactivated pi complexes, backbonding is dominated by charge donation from the phosphines, which allows for strong backdonation even though the metal centre retains a formal d10 electronic configuration. We describe this interaction as a formal 3-centre-4-electron (3c-4e) interaction where the nickel centre mediates charge transfer from the phosphine σ-donors to the π*ip ligand acceptor orbital. The implications of this unusual bonding motif are described with respect to both geometric structure and reactivity.},
 bibtype = {article},
 author = {Desnoyer, Addison N. and He, Weiying and Behyan, Shirin and Chiu, Weiling and Love, Jennifer A. and Kennepohl, Pierre},
 doi = {10.1002/chem.201805987},
 journal = {Chemistry - A European Journal},
 number = {20}
}

Ni π-complexes are widely postulated as intermediates in organometallic chemistry. However, the nature of the bonding in such complexes has not been extensively studied. Herein, we probe the geometric and electronic structure of a series of nickel π-complexes using a combination of 31P NMR, Ni K-edge XAS, Ni Kβ XES, and supporting density-functional computations. These complexes are best described as square planar d10 complexes with π-backbonding acting as the dominant factor in the M-L bond to the π ligand. The degree of backbonding correlates with both 2JPP and the energy of the clearly observable Ni 1s→4pz pre-edge transition in the Ni K-edge XAS data. The degree of backbonding is determined by the energy of the π*ip ligand acceptor orbital: unactivated olefinic ligands tend to be poor π-acids whereas ketones, aldehydes, and esters allow for greater backbonding. The strength of the backbonding from the neutral Ni(dtbpe) molecular fragment is dramatically increased via σ donation from the diphosphine ligands. In fact, in unactivated pi complexes, backbonding is dominated by charge donation from the phosphines, which allows for strong backdonation even though the metal centre retains a formal d10 electronic configuration. We describe this interaction as a formal 3-centre-4-electron (3c-4e) interaction where the nickel centre mediates charge transfer from the phosphine σ-donors to the π*ip ligand acceptor orbital. The implications of this unusual bonding motif are described with respect to both geometric structure and reactivity.

@article{
 title = {Green synthesis of copper oxide nanoparticles using sinapic acid: an underpinning step towards antiangiogenic therapy for breast cancer},
 type = {article},
 year = {2019},
 keywords = {Bioinorganic Chemistry,XPS},
 pages = {633-645},
 volume = {24},
 websites = {http://link.springer.com/10.1007/s00775-019-01676-z},
 month = {8},
 publisher = {Springer Berlin Heidelberg},
 day = {22},
 id = {b8a5b579-f374-3a92-a416-803a72e1df5f},
 created = {2019-06-25T16:29:42.918Z},
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 last_modified = {2020-03-24T20:46:27.968Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 bibtype = {article},
 author = {Raj Preeth, Desingh and Shairam, Manickaraj and Suganya, Natarajan and Hootan, Roshandel and Kartik, Ravishankar and Pierre, Kennepohl and Suvro, Chatterjee and Rajalakshmi, Subramaniyam},
 doi = {10.1007/s00775-019-01676-z},
 journal = {JBIC Journal of Biological Inorganic Chemistry},
 number = {5}
}

@article{
 title = {Direct experimental evaluation of ligand-induced backbonding in nickel metallacyclic complexes},
 type = {article},
 year = {2019},
 pages = {133-143},
 volume = {220},
 websites = {http://dx.doi.org/10.1039/C9FD00041K,http://xlink.rsc.org/?DOI=C9FD00041K},
 publisher = {Royal Society of Chemistry},
 id = {503ef446-2933-3803-b733-724858ae1263},
 created = {2019-12-06T21:51:27.082Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:19.611Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 folder_uuids = {ebbabfbd-939b-434c-8a89-bba932203a0b},
 private_publication = {false},
 abstract = {The details of ligand-induced backbonding in nickel diphosphine π complexes are explored using nickel L-edge (3d←2p) X-ray absorption spectroscopy as a means of quantifying the degree of backbonding derived from direct Ni 3d donation into the π ligand.},
 bibtype = {article},
 author = {He, Weiying and Kennepohl, Pierre},
 doi = {10.1039/C9FD00041K},
 journal = {Faraday Discussions},
 keywords = {Computational,SSRL,X-ray Absorption Spectroscopy}
}

The details of ligand-induced backbonding in nickel diphosphine π complexes are explored using nickel L-edge (3d←2p) X-ray absorption spectroscopy as a means of quantifying the degree of backbonding derived from direct Ni 3d donation into the π ligand.

@article{
 title = {Physical methods for mechanistic understanding: general discussion},
 type = {article},
 year = {2019},
 pages = {144-178},
 volume = {220},
 websites = {http://xlink.rsc.org/?DOI=C9FD90070E},
 id = {9d5ad4df-6bf1-3745-85ee-c5a1703d1ebf},
 created = {2019-12-06T21:51:27.127Z},
 file_attached = {true},
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 last_modified = {2020-04-22T14:44:12.887Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 bibtype = {article},
 author = {Aoki, Yutaka and Bauer, Matthias and Braun, Thomas and Cadge, Jamie and Davies, David and Durand, Derek J and Eisenstein, Odile and Ess, Daniel and Fairlamb, Ian and Fey, Natalie and Gallarati, Simone and George, Mike and Greaves, Megan and Halse, Meghan and Hamilton, Alexander and Harvey, Jeremy and Haynes, Anthony and Hintermair, Ulrich and Hulme, Alison N and Ishii, Youichi and Jakoobi, Martin and Jensen, Vidar R and Kennepohl, Pierre and Kuwata, Shigeki and Lei, Aiwen and Lloyd-Jones, Guy and Love, Jennifer and Lovelock, Kevin and Lynam, Jason and Macgregor, Stuart and Marder, Todd B and Meijer, Evert Jan and Morgan, Patrick and Morris, Robert H and Mwansa, Joseph and Nelson, David and Odom, Aaron and Perutz, Robin and Reiher, Markus and Renny, Joseph and Roithová, Jana and Schafer, Laurel and Schilter, David and Scott, Samuel and Slattery, John and Walton, James and Wilden, Jonathan D and Wong, Chun-Yuen and Yaman, Tolga and Young, Tom},
 doi = {10.1039/C9FD90070E},
 journal = {Faraday Discussions},
 keywords = {Perspective}
}

@article{
 title = {Mechanistic insight into organic and industrial transformations: General discussion},
 type = {article},
 year = {2019},
 volume = {220},
 id = {559be10e-9daa-3e2e-b8bd-a9fc80741008},
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 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {false},
 hidden = {false},
 private_publication = {true},
 bibtype = {article},
 author = {Aoki, Y. and Bauer, M. and Braun, T. and Cadge, J.A. and Clarke, G.E. and Durand, D.J. and Eisenstein, O. and Gallarati, S. and Greaves, M. and Harvey, J. and Haynes, A. and Hintermair, U. and Hulme, A.N. and Ishii, Y. and Jakoobi, M. and Jensen, V.R. and Kennepohl, P. and Kuwata, S. and Lei, A. and Lloyd-Jones, G. and Love, J. and Lynam, J. and MacGregor, S. and Morris, R.H. and Nelson, D. and Odom, A. and Perutz, R. and Reiher, M. and Renny, J. and Roithova, J. and Schafer, L. and Scott, S. and Seavill, P.W. and Slattery, J. and Takao, T. and Walton, J. and Wilden, J.D. and Wong, C.-Y. and Young, T.},
 doi = {10.1039/C9FD90072A},
 journal = {Faraday Discussions}
}

@article{
 title = {Reacted copper(II) concentrations in amine amended micronized copper treated red pine and lodgepole pine},
 type = {article},
 year = {2018},
 keywords = {Bioinorganic Chemistry,EPR,Wood Preservation},
 pages = {337-343},
 volume = {76},
 websites = {http://link.springer.com/10.1007/s00107-016-1069-3},
 month = {1},
 day = {21},
 id = {06815038-5acd-3c85-877a-be22d3f3e77c},
 created = {2017-09-06T15:15:24.073Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-01-30T06:03:26.531Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 folder_uuids = {42212cd4-c269-472c-b4ae-b7cebf7fec81},
 private_publication = {false},
 bibtype = {article},
 author = {Xue, Wei and Kennepohl, Pierre and Ruddick, John N R},
 doi = {10.1007/s00107-016-1069-3},
 journal = {Eur. J. Wood Prod.},
 number = {1}
}

@article{
 title = {Disproportionation Reactions of an Organometallic Ni(I) Amidate Complex: Scope and Mechanistic Investigations},
 type = {article},
 year = {2018},
 pages = {1392-1399},
 volume = {37},
 websites = {http://dx.doi.org/10.1021/acs.organomet.8b00074,http://pubs.acs.org/doi/10.1021/acs.organomet.8b00074},
 month = {5},
 day = {14},
 id = {3376757a-3d36-3fbc-8fdf-b975bc026fec},
 created = {2018-04-20T18:10:51.125Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:12.877Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 bibtype = {article},
 author = {Beattie, D. Dawson and Lascoumettes, Gautier and Kennepohl, Pierre and Love, Jennifer A and Schafer, Laurel L},
 doi = {10.1021/acs.organomet.8b00074},
 journal = {Organometallics},
 number = {9},
 keywords = {Computational,EPR}
}

@article{
 title = {Identifying the missing link in catalyst transfer polymerization},
 type = {article},
 year = {2018},
 pages = {3866},
 volume = {9},
 websites = {http://www.nature.com/articles/s41467-018-06324-9,http://dx.doi.org/10.26434/chemrxiv.5758608.v2},
 month = {12},
 publisher = {Springer US},
 day = {24},
 id = {c3bd3051-410a-3f12-b00f-8d7a60da283d},
 created = {2018-10-10T21:02:46.362Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
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 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 abstract = {Nickel-catalyzed catalyst transfer polycondensation (CTP) of thiophenes is an efficient strategy for the controlled synthesis of polythiophenes. However, a detailed view of its reaction mechanism has remained elusive with unresolved questions regarding the geometry and bonding of critical Ni(0) thiophene intermediates. Herein, we provide experimental and computational evidence of structurally characterized square planar η2-Ni(0)–thiophene species and their relevance to the mechanism of CTP. These results confirm the viability of C,C-η2 bound intermediates in CTP of thiophenes, providing an electronic rationale for the stability of such species, and thus that such processes can proceed as living polymerizations. We further show that C,S-κ2 species may also be relevant in nickel-catalyzed CTP of thiophenes, providing new avenues for exploitation and optimization.},
 bibtype = {article},
 author = {He, Weiying and Patrick, Brian O. and Kennepohl, Pierre},
 doi = {10.1038/s41467-018-06324-9},
 journal = {Nature Communications},
 number = {1},
 keywords = {Computational,Organometallic Chemistry,SSRL,X-ray Absorption Spectroscopy}
}

Nickel-catalyzed catalyst transfer polycondensation (CTP) of thiophenes is an efficient strategy for the controlled synthesis of polythiophenes. However, a detailed view of its reaction mechanism has remained elusive with unresolved questions regarding the geometry and bonding of critical Ni(0) thiophene intermediates. Herein, we provide experimental and computational evidence of structurally characterized square planar η2-Ni(0)–thiophene species and their relevance to the mechanism of CTP. These results confirm the viability of C,C-η2 bound intermediates in CTP of thiophenes, providing an electronic rationale for the stability of such species, and thus that such processes can proceed as living polymerizations. We further show that C,S-κ2 species may also be relevant in nickel-catalyzed CTP of thiophenes, providing new avenues for exploitation and optimization.

@article{
 title = {Spectroscopic detection of halogen bonding resolves dye regeneration in the dye-sensitized solar cell},
 type = {article},
 year = {2017},
 keywords = {Halogen Bonding,SSRL,X-ray Absorption Spectroscopy},
 pages = {1761},
 volume = {8},
 websites = {http://www.nature.com/articles/s41467-017-01726-7},
 month = {12},
 day = {24},
 id = {dc346c14-2488-330a-8429-7ddb68798049},
 created = {2017-10-13T00:04:27.142Z},
 file_attached = {true},
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 last_modified = {2020-04-22T14:44:11.861Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Parlane2017},
 private_publication = {false},
 bibtype = {article},
 author = {Parlane, Fraser G. L. and Mustoe, Chantal L and Kellett, Cameron W. and Simon, Sarah J. and Swords, Wesley B. and Meyer, Gerald J. and Kennepohl, Pierre and Berlinguette, Curtis P},
 doi = {10.1038/s41467-017-01726-7},
 journal = {Nature Commun.},
 number = {1}
}

@article{
 title = {Beyond the halogen bond: general discussion},
 type = {article},
 year = {2017},
 keywords = {Halogen Bonding},
 pages = {227-244},
 volume = {203},
 websites = {http://xlink.rsc.org/?DOI=C7FD90062G},
 id = {b69e5817-5ae9-3f6c-908f-e7ae272ff638},
 created = {2017-10-16T15:38:24.131Z},
 file_attached = {true},
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 last_modified = {2018-01-30T06:06:18.363Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 bibtype = {article},
 author = {Aakeröy, Christer B. and Alavi, Saman and Beer, Paul D and Beyeh, Ngong Kodiah and Brammer, Lee and Bryce, David L. and Clark, Timothy and Cottrell, Simon J. and Del Bene, Janet E. and Edwards, Alison J. and Esterhuysen, Catharine and Friščić, Tomislav and Guru Row, Tayur N. and Kennepohl, Pierre and Lloyd, Gareth O. and Roy Choudhury, Angshuman and Scheiner, Steve and Southern, Scott A. and Taylor, Mark S. and Tsuzuki, Seiji and Vargas-Baca, Ignacio},
 doi = {10.1039/C7FD90062G},
 journal = {Faraday Discuss.}
}

@article{
 title = {The halogen bond in solution: general discussion},
 type = {article},
 year = {2017},
 keywords = {Perspective},
 pages = {347-370},
 volume = {203},
 websites = {http://xlink.rsc.org/?DOI=C7FD90063E},
 id = {f3c6b142-9316-3659-9d61-ba316f77aae1},
 created = {2017-10-16T15:38:24.140Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:12.853Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
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 bibtype = {article},
 author = {Aakeröy, Christer B. and Beer, Paul D and Beyeh, Ngong Kodiah and Brammer, Lee and Branca, Mathieu and Bryce, David L. and Del Bene, Janet E. and Edwards, Alison J. and Erdelyi, Mate and Esterhuysen, Catharine and Fourmigué, Marc and Kennepohl, Pierre and Lee, Lucia Myongwon and Mosquera, Marta E. G. and Murray, Jane S. and Mustoe, Chantal L and Pennington, William T. and Politzer, Peter and Riley, Kevin E. and Rosokha, Sergiy V and Scheiner, Steve and Taylor, Mark S. and Tsuzuki, Seiji and Vargas-Baca, Ignacio and Xu, Yijue},
 doi = {10.1039/C7FD90063E},
 journal = {Faraday Discuss.}
}

@article{
 title = {Computational approaches and sigma-hole interactions: general discussion},
 type = {article},
 year = {2017},
 keywords = {Perspective},
 pages = {131-163},
 volume = {203},
 websites = {http://xlink.rsc.org/?DOI=C7FD90061A},
 id = {99930ab2-242e-320e-b209-3ecc4097abc7},
 created = {2017-10-16T15:38:24.664Z},
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 last_modified = {2020-04-22T14:44:11.591Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
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 bibtype = {article},
 author = {Aakeröy, Christer B. and Alavi, Saman and Brammer, Lee and Bryce, David L. and Clark, Timothy and Del Bene, Janet E. and Edwards, Alison J. and Esterhuysen, Catharine and Guru Row, Tayur N. and Kennepohl, Pierre and Legon, Anthony C. and Lloyd, Gareth O. and Murray, Jane S. and Pennington, William T. and Politzer, Peter and Riley, Kevin E. and Rosokha, Sergiy V and Scheiner, Steve and Tsuzuki, Seiji and Vargas-Baca, Ignacio},
 doi = {10.1039/C7FD90061A},
 journal = {Faraday Discuss.}
}

@article{
 title = {Probing covalency in halogen bonds through donor K-edge X-ray absorption spectroscopy: polyhalides as coordination complexes},
 type = {article},
 year = {2017},
 keywords = {Computational,SSRL,X-ray Absorption Spectroscopy},
 pages = {79-91},
 volume = {203},
 websites = {http://pubs.rsc.org/en/Content/ArticleLanding/2017/FD/C7FD00076F,http://xlink.rsc.org/?DOI=C7FD00076F},
 publisher = {Royal Society of Chemistry},
 id = {72bc46c1-f5a5-3ecf-95d1-02aab68eadcf},
 created = {2017-10-19T18:41:31.651Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:17.818Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Mustoe2017},
 folder_uuids = {ebbabfbd-939b-434c-8a89-bba932203a0b},
 private_publication = {false},
 abstract = {The properties of halogen bonds (XBs) in solid-state I 2 X − and I 4 X − materials (where X = Cl, Br) are explored using donor K-edge X-ray absorption spectroscopy (XAS) to experimentally determine the degree of charge transfer in such XB interactions. The degree of covalency in these bonds is substantial, even in cases where significantly weaker secondary interactions are observed. These data, in concert with previous work in this area, suggests that certain halogen bonds have covalent contributions to bonding that are similar to, and even exceed, those observed in transition metal coordinate bonds. For this reason, we suggest that XB interactions of this type be denoted in a similar way to coordination bonds (X → Y) as opposed to using a representation that is the same as for significantly less covalent hydrogen bonds (X⋯Y).},
 bibtype = {article},
 author = {Mustoe, Chantal L and Gunabalasingam, Mathusan and Yu, Darren and Patrick, Brian O. and Kennepohl, Pierre},
 doi = {10.1039/C7FD00076F},
 journal = {Faraday Discuss.}
}

The properties of halogen bonds (XBs) in solid-state I 2 X − and I 4 X − materials (where X = Cl, Br) are explored using donor K-edge X-ray absorption spectroscopy (XAS) to experimentally determine the degree of charge transfer in such XB interactions. The degree of covalency in these bonds is substantial, even in cases where significantly weaker secondary interactions are observed. These data, in concert with previous work in this area, suggests that certain halogen bonds have covalent contributions to bonding that are similar to, and even exceed, those observed in transition metal coordinate bonds. For this reason, we suggest that XB interactions of this type be denoted in a similar way to coordination bonds (X → Y) as opposed to using a representation that is the same as for significantly less covalent hydrogen bonds (X⋯Y).

@inproceedings{
 title = {Mechanisms of varnish formation and implications for the use of varnish-removal technology},
 type = {inproceedings},
 year = {2017},
 keywords = {EPR},
 id = {804afaa6-0131-3205-89d7-8af4bf4bf9c1},
 created = {2017-12-19T00:12:58.684Z},
 file_attached = {false},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:11.522Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 abstract = {Thermo-oxidative lubricant breakdown leads to varnish formation. Radical process. EPR study of radical intermediates involved in oxidation revealed:•Initiation of breakdown does not require O2 as previously thought.Oil hydrocarbons form radicals on their own. Role of O 2 : trap which promotes radical propagation. Results in O 2 incorporation to form polar breakdown products. Polar products result in varnish formation.2 Strategies to mitigate the risk of lubricant varnishing: 1.Don't allow polar breakdown products to form: • Limit lubricant exposure to O 2 using inert N 2 blanket. 2. Remove any polar breakdown products which do form: • Use resin to remove soluble polar species before they can form varnish. Improve lubricant condition and maintain it even under degrading conditions.},
 bibtype = {inproceedings},
 author = {Hobbs, M.G. and Dufresne, P. and Behyan, S. and Kennepohl, Pierre},
 booktitle = {72nd Annual Meeting and Exhibition of the Society of Tribologists and Lubrication Engineers, STLE 2017}
}

Thermo-oxidative lubricant breakdown leads to varnish formation. Radical process. EPR study of radical intermediates involved in oxidation revealed:•Initiation of breakdown does not require O2 as previously thought.Oil hydrocarbons form radicals on their own. Role of O 2 : trap which promotes radical propagation. Results in O 2 incorporation to form polar breakdown products. Polar products result in varnish formation.2 Strategies to mitigate the risk of lubricant varnishing: 1.Don't allow polar breakdown products to form: • Limit lubricant exposure to O 2 using inert N 2 blanket. 2. Remove any polar breakdown products which do form: • Use resin to remove soluble polar species before they can form varnish. Improve lubricant condition and maintain it even under degrading conditions.

@article{
 title = {Solid-state chemistry and applications: general discussion},
 type = {article},
 year = {2017},
 keywords = {Perspective},
 pages = {459-483},
 volume = {203},
 websites = {http://xlink.rsc.org/?DOI=C7FD90064C,http://pubs.rsc.org/en/content/articlepdf/2017/fd/c7fd90064c},
 id = {35dc00e3-b636-375f-9bda-dd0ab3fee69c},
 created = {2018-04-26T18:35:25.554Z},
 accessed = {2018-02-07},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:12.882Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 folder_uuids = {99a1c984-74d2-435b-a0ee-48b9100867d9},
 private_publication = {false},
 abstract = {No abstract available},
 bibtype = {article},
 author = {Aakeröy, Christer B. and Alavi, Saman and Beyeh, Ngong Kodiah and Brammer, Lee and Branca, Mathieu and Bryce, David L. and Christopherson, Jan-Constantin and Clark, Timothy and Cottrell, Simon J. and Del Bene, Janet E. and Dichiarante, Valentina and Edwards, Alison J. and Erdelyi, Mate and Esterhuysen, Catharine and Fourmigué, Marc and Friščić, Tomislav and Kennepohl, Pierre and Legon, Anthony C. and Lloyd, Gareth O. and Murray, Jane S. and Mustoe, Chantal L and Pennington, William T. and Rosokha, Sergiy V and Roy Choudhury, Angshuman and Scheiner, Steve and Szell, Patrick M. J. and Taylor, Mark S. and Tsuzuki, Seiji},
 doi = {10.1039/C7FD90064C},
 journal = {Faraday Discuss.},
 number = {459}
}

No abstract available

@article{
 title = {Reexamining Oxidation States during the Synthesis of 2-Rhodaoxetanes from Olefins},
 type = {article},
 year = {2016},
 keywords = {CLS},
 pages = {13-15},
 volume = {55},
 websites = {http://pubs.acs.org/doi/10.1021/acs.inorgchem.5b02703},
 month = {1},
 day = {4},
 id = {fa8cc2bb-66af-3945-ab55-22692fc71d27},
 created = {2017-09-06T15:14:56.845Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2019-04-10T17:38:30.704Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Desnoyer2016},
 private_publication = {false},
 bibtype = {article},
 author = {Desnoyer, Addison N. and Behyan, Shirin and Patrick, Brian O. and Dauth, Alexander and Love, Jennifer A and Kennepohl, Pierre},
 doi = {10.1021/acs.inorgchem.5b02703},
 journal = {Inorg. Chem.},
 number = {1}
}

@article{
 title = {Even the normal is abnormal: N-heterocyclic carbene C 2 binding to a phosphaalkene without breaking the P-C π-bond},
 type = {article},
 year = {2016},
 keywords = {Westgrid},
 pages = {998-1001},
 volume = {52},
 websites = {http://xlink.rsc.org/?DOI=C5CC08181E},
 id = {dcb9433f-95fd-329f-83c1-858e24894fa0},
 created = {2017-09-06T15:15:18.706Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:32:08.166Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 abstract = {The reaction of MesPQCPh2 with the least sterically demanding N-heterocyclic carbene (NHC = IMe) results in formation of the ‘abnormal’ (C4 -substituted) 4-phosphino-NHC (1). In contrast, reaction with Me2IMe gives the unprecedented ‘normal’ C2 adduct, Me2IMe - P(Mes)QCPh2 (2). Particularly striking is the asymmetric and weak bonding of the NHC to the PQC moiety in 2. DFT calculations indicate that the PQC natural bond order in 2 (1.54) still reflects significant pi-character to the bond (cf. MesPQCPh2: NBO = 1.98). Further computational analysis suggests that p-delocalization into the remote C-phenyl substituents is key to stabilizing the NHC adduct.},
 bibtype = {article},
 author = {Majhi, Paresh Kumar and Chow, Keith C F and Hsieh, Tom H H and Bowes, Eric G and Schnakenburg, Gregor and Kennepohl, Pierre and Streubel, Rainer and Gates, Derek P},
 doi = {10.1039/C5CC08181E},
 journal = {Chem. Commun.},
 number = {5}
}

The reaction of MesPQCPh2 with the least sterically demanding N-heterocyclic carbene (NHC = IMe) results in formation of the ‘abnormal’ (C4 -substituted) 4-phosphino-NHC (1). In contrast, reaction with Me2IMe gives the unprecedented ‘normal’ C2 adduct, Me2IMe - P(Mes)QCPh2 (2). Particularly striking is the asymmetric and weak bonding of the NHC to the PQC moiety in 2. DFT calculations indicate that the PQC natural bond order in 2 (1.54) still reflects significant pi-character to the bond (cf. MesPQCPh2: NBO = 1.98). Further computational analysis suggests that p-delocalization into the remote C-phenyl substituents is key to stabilizing the NHC adduct.

@article{
 title = {Solubilisation and chemical fixation of copper(II) in micronized copper treated wood},
 type = {article},
 year = {2016},
 keywords = {Bioinorganic Chemistry,EPR,Wood Preservation},
 pages = {3679-3686},
 volume = {45},
 websites = {http://pubs.rsc.org/en/Content/ArticleLanding/2016/DT/C5DT03159A,http://xlink.rsc.org/?DOI=C5DT03159A},
 id = {d2deb7e8-9aa8-30a9-a110-fe34ce6e7153},
 created = {2017-09-06T15:15:21.474Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-02-08T00:33:42.106Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 bibtype = {article},
 author = {Xue, Wei and Ruddick, John N R and Kennepohl, Pierre},
 doi = {10.1039/C5DT03159A},
 journal = {Dalton Trans.},
 number = {9}
}

@article{
 title = {Interactions between major chlorogenic acid isomers and chemical changes in coffee brew that affect antioxidant activities},
 type = {article},
 year = {2016},
 keywords = {EPR},
 pages = {251-259},
 volume = {213},
 websites = {http://dx.doi.org/10.1016/j.foodchem.2016.06.041,http://linkinghub.elsevier.com/retrieve/pii/S0308814616309347},
 month = {12},
 id = {25890755-a162-3ca3-8645-5aa6ba4939d8},
 created = {2019-01-29T16:31:30.992Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2019-01-29T16:31:33.524Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 folder_uuids = {9d611e4e-8236-4fa2-b457-8d75c7f530d0},
 private_publication = {false},
 bibtype = {article},
 author = {Liang, Ningjian and Xue, Wei and Kennepohl, Pierre and Kitts, David D.},
 doi = {10.1016/j.foodchem.2016.06.041},
 journal = {Food Chemistry}
}

@article{
 title = {Reacted copper(II) concentrations in earlywood and latewood of micronized copper-treated Canadian softwood species},
 type = {article},
 year = {2015},
 keywords = {Bioinorganic Chemistry,EPR,Wood Preservation},
 pages = {509-512},
 volume = {69},
 websites = {http://www.degruyter.com/view/j/hfsg.ahead-of-print/hf-2014-0128/hf-2014-0128.xml},
 id = {2e1e70e2-c249-381f-9ff0-90b3e9c06f61},
 created = {2017-09-06T15:15:04.275Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:26:46.957Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 abstract = {Electron paramagnetic resonance was used in conjunction with X-ray fluorescence spectroscopy to quantify total copper and reacted copper retentions in MCQ and MCA treated Canadian red pine sapwood and western hemlock heartwood. Total copper retentions were distinctly different between earlywood and latewood of both softwood species examined. Earlywood of red pine sapwood had higher total copper content than the latewood, while western hemlock heartwood had higher total copper contents in latewood than earlywood. The reacted copper concentrations were similar in earlywood and latewood, reflecting a similar capacity of each to solubilize and complex the reacted copper.},
 bibtype = {article},
 author = {Xue, Wei and Kennepohl, Pierre and Ruddick, John N.R.},
 doi = {10.1515/hf-2014-0128},
 journal = {Holzforschung},
 number = {4}
}

Electron paramagnetic resonance was used in conjunction with X-ray fluorescence spectroscopy to quantify total copper and reacted copper retentions in MCQ and MCA treated Canadian red pine sapwood and western hemlock heartwood. Total copper retentions were distinctly different between earlywood and latewood of both softwood species examined. Earlywood of red pine sapwood had higher total copper content than the latewood, while western hemlock heartwood had higher total copper contents in latewood than earlywood. The reacted copper concentrations were similar in earlywood and latewood, reflecting a similar capacity of each to solubilize and complex the reacted copper.

@article{
 title = {Pyridonate-Supported Titanium(III). Benzylamine as an Easy-To-Use Reductant},
 type = {article},
 year = {2015},
 keywords = {EPR},
 pages = {4941-4945},
 volume = {34},
 websites = {http://pubs.acs.org/doi/10.1021/acs.organomet.5b00469},
 month = {10},
 day = {26},
 id = {d3dbfb8a-9bee-3c2d-9663-83f229a9df3b},
 created = {2017-09-06T15:15:20.751Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-10-19T01:44:52.356Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 abstract = {The reaction of bis(3-phenyl-2-pyridonate)Ti- (NMe2)2 with excess benzylamine leads to an unexpected reduction of the metal center from Ti(IV) to Ti(III). The reduced titanium species was isolated and revealed as tris(3- phenyl-2-pyridonate)Ti(NH2Bn)2. Ammonia and N-benzyl-1- phenylmethanimine are released as byproducts of the reaction, thereby confirming benzylamine as a mild reductant. This new pyridonate-supported titanium(III) complex has been fully characterized, and experimental data and theoretical calculations confirm a d1 metal center with no ligand-based radical character. This Ti(III) complex does not react with aminoalkenes, suggesting that radical species are not viable intermediates for the hydroaminoalkylation or hydroamination reaction.},
 bibtype = {article},
 author = {Chong, Eugene and Xue, Wei and Storr, Tim and Kennepohl, Pierre and Schafer, Laurel L.},
 doi = {10.1021/acs.organomet.5b00469},
 journal = {Organometallics},
 number = {20}
}

The reaction of bis(3-phenyl-2-pyridonate)Ti- (NMe2)2 with excess benzylamine leads to an unexpected reduction of the metal center from Ti(IV) to Ti(III). The reduced titanium species was isolated and revealed as tris(3- phenyl-2-pyridonate)Ti(NH2Bn)2. Ammonia and N-benzyl-1- phenylmethanimine are released as byproducts of the reaction, thereby confirming benzylamine as a mild reductant. This new pyridonate-supported titanium(III) complex has been fully characterized, and experimental data and theoretical calculations confirm a d1 metal center with no ligand-based radical character. This Ti(III) complex does not react with aminoalkenes, suggesting that radical species are not viable intermediates for the hydroaminoalkylation or hydroamination reaction.

@article{
 title = {Electrophilic Activation of Oxidized Sulfur Ligands and Implications for the Biological Activity of Ruthenium(II) Arene Anticancer Complexes},
 type = {article},
 year = {2015},
 keywords = {CLS,Westgrid},
 pages = {11574-11580},
 volume = {54},
 websites = {http://pubs.acs.org/doi/10.1021/acs.inorgchem.5b02493},
 month = {12},
 day = {7},
 id = {0952e97f-5c32-377b-94cf-b20e3c16a3b1},
 created = {2017-09-06T15:15:20.961Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-12-05T17:36:39.592Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Sriskandakumar2015},
 private_publication = {false},
 abstract = {Surprisingly, the anticancer activity of half-sandwich Ru arene complexes [(η6-arene)Ru(en)Cl]+ appears to be promoted and not inhibited by binding to the intracellular thiol glutathione. Labilization of the Ru?S bond allowing DNA binding appeared to be initiated by oxygenation of the thiolate ligand, although oxidation by itself did not seem to weaken the Ru?S bond. In this study, we have investigated the solvation and acidic perturbations of mono (sulfenato) and bis (sulfinato) oxidized species of [(η6-arene)Ru(en) (SR)]+ complex in the presence of Brønsted and Lewis acids. Sulfur K-edge X-ray absorption spectroscopy together with density functional theory calculations show that solvation and acidic perturbation of sulfenato species produce a significant decrease in the S3p character of the Ru?S bond (Ru4dσ* ← S1s charge donation). Also there is a drastic fall in the overall ligand charge donation to the metal center in both sulfenato and sulfinato species. Our investigation clearly shows that mono oxidized sulfenato species are most susceptible to ligand exchange, hence providing a possible pathway for in vivo activation and biological activity.},
 bibtype = {article},
 author = {Sriskandakumar, Thamayanthy and Behyan, Shirin and Habtemariam, Abraha and Sadler, Peter J. and Kennepohl, Pierre},
 doi = {10.1021/acs.inorgchem.5b02493},
 journal = {Inorg. Chem.},
 number = {23}
}

Surprisingly, the anticancer activity of half-sandwich Ru arene complexes [(η6-arene)Ru(en)Cl]+ appears to be promoted and not inhibited by binding to the intracellular thiol glutathione. Labilization of the Ru?S bond allowing DNA binding appeared to be initiated by oxygenation of the thiolate ligand, although oxidation by itself did not seem to weaken the Ru?S bond. In this study, we have investigated the solvation and acidic perturbations of mono (sulfenato) and bis (sulfinato) oxidized species of [(η6-arene)Ru(en) (SR)]+ complex in the presence of Brønsted and Lewis acids. Sulfur K-edge X-ray absorption spectroscopy together with density functional theory calculations show that solvation and acidic perturbation of sulfenato species produce a significant decrease in the S3p character of the Ru?S bond (Ru4dσ* ← S1s charge donation). Also there is a drastic fall in the overall ligand charge donation to the metal center in both sulfenato and sulfinato species. Our investigation clearly shows that mono oxidized sulfenato species are most susceptible to ligand exchange, hence providing a possible pathway for in vivo activation and biological activity.

@article{
 title = {Evidence for Halogen Bond Covalency in Acyclic and Interlocked Halogen-Bonding Receptor Anion Recognition},
 type = {article},
 year = {2015},
 keywords = {SSRL},
 pages = {499-507},
 volume = {137},
 websites = {http://pubs.acs.org/doi/10.1021/ja511648d},
 month = {1},
 day = {14},
 id = {e215d3f3-5260-3313-9dc5-ba81232661c9},
 created = {2017-09-06T15:15:21.762Z},
 accessed = {2014-12-12},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:17.376Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Robinson2015},
 folder_uuids = {e286fe6d-1c93-4648-bac6-84acad56f4e5,ebbabfbd-939b-434c-8a89-bba932203a0b},
 private_publication = {false},
 abstract = {The synthesis and anion binding properties of novel halogen-bonding (XB) bis-iodotriazole-pyridinium-containing acyclic and [2]catenane anion host systems are described. The XB acyclic receptor displays selectivity for acetate over halides with enhanced anion recognition properties compared to the analogous hydrogen bonding (HB) acyclic receptor. A reversal in halide selectivity is observed in the XB [2]catenane, in comparison to the acyclic XB receptor, due to the interlocked host's unique three-dimensional binding cavity, and no binding is observed for oxoanions. Notable halide anion association constant values determined for the [2]catenane in competitive organic-aqueous solvent mixtures demonstrate considerable enhancement of anion recognition as compared to the HB catenane analogue. X-ray crystallographic analysis of a series of halide catenane complexes reveal strong XB interactions in the solid state. These interactions were studied using Cl and Br K-edge X-ray Absorption Spectroscopy (XAS) indicating intense pre-edge features characteristic of charge transfer from the halide to its bonding partner (σ_("AX←" "X" ^-)^*←"X" _1s), and providing a direct measure of the degree of covalency in the halogen bond(s). The data reveal that the degree of covalency is similar to that which is observed in transition metal coordinate covalent bonds. These results are supported by DFT results, which correlate well with the experimental data.},
 bibtype = {article},
 author = {Robinson, Sean W and Mustoe, Chantal L and White, Nicholas G and Brown, Asha and Thompson, Amber L and Kennepohl, Pierre and Beer, Paul D},
 doi = {10.1021/ja511648d},
 journal = {J. Am. Chem. Soc.},
 number = {1}
}

The synthesis and anion binding properties of novel halogen-bonding (XB) bis-iodotriazole-pyridinium-containing acyclic and [2]catenane anion host systems are described. The XB acyclic receptor displays selectivity for acetate over halides with enhanced anion recognition properties compared to the analogous hydrogen bonding (HB) acyclic receptor. A reversal in halide selectivity is observed in the XB [2]catenane, in comparison to the acyclic XB receptor, due to the interlocked host's unique three-dimensional binding cavity, and no binding is observed for oxoanions. Notable halide anion association constant values determined for the [2]catenane in competitive organic-aqueous solvent mixtures demonstrate considerable enhancement of anion recognition as compared to the HB catenane analogue. X-ray crystallographic analysis of a series of halide catenane complexes reveal strong XB interactions in the solid state. These interactions were studied using Cl and Br K-edge X-ray Absorption Spectroscopy (XAS) indicating intense pre-edge features characteristic of charge transfer from the halide to its bonding partner (σ_("AX←" "X" ^-)^*←"X" _1s), and providing a direct measure of the degree of covalency in the halogen bond(s). The data reveal that the degree of covalency is similar to that which is observed in transition metal coordinate covalent bonds. These results are supported by DFT results, which correlate well with the experimental data.

@article{
 title = {Characterization of Copper in Leachates from ACQ- and MCQ-treated wood and its effects on Basidiopore Germination},
 type = {article},
 year = {2015},
 keywords = {Bioinorganic Chemistry,Electron Paramagnetic Resonance Spectroscopy,Wood Preservation},
 pages = {209-216},
 volume = {47},
 id = {661985ed-44b1-3340-a544-4aedc155027b},
 created = {2017-12-19T00:12:58.738Z},
 file_attached = {false},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-02-08T00:33:41.914Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 abstract = {The unpenetrated interior of wood with a shell of preservative treatment may be exposed when the wood is cut or when checks open up. Mobile copper from wood shell-treated with chromated copper arsenate (CCA) has been shown to protect cut ends and checks against basidiospore germination. However, recent observations found that leachates from alkaline copper quat (ACQ)-treated wood failed to prevent basidiospore germination on untreated wood although copper levels were higher than toxic thresholds previously identified. It was hypothesized that the copper in leachate from ACQ-treated wood may be coordinated with monoethanolamine and/or lignin-based ligands and that this may result in poorer performance against basidiospores. In this study, electron paramagnetic resonance spectroscopy was used to determine the form of copper in leachates from ACQ, micronized copper quat (MCQ), and copper- sulfate-treated wood. Leachates from ACQ-treated wood contained at least some degree of coordination with a nitrogen- and oxygen-containing ligand, probably monoethanolamine. This was not detected in leachates from MCQ and copper-sulfate-treated wood. These leachates were further evaluated for their ability to inhibit germination of Tyromyces palustris basidiospores. At low concentrations of copper, the CuSO4 and MCQ leachates were more effective than the ACQ leachate. At high concentrations CuSO4 and MCQ, leachates prevented germination in all samples, whereas ACQ leachates prevented germination in all but one sample. Keywords:},
 bibtype = {article},
 author = {Stirling, Rod and Ruddick, John N R R and Xue, Wei and Morris, Paul I and Kennepohl, Pierre},
 journal = {Wood Fiber Sci.},
 number = {3}
}

The unpenetrated interior of wood with a shell of preservative treatment may be exposed when the wood is cut or when checks open up. Mobile copper from wood shell-treated with chromated copper arsenate (CCA) has been shown to protect cut ends and checks against basidiospore germination. However, recent observations found that leachates from alkaline copper quat (ACQ)-treated wood failed to prevent basidiospore germination on untreated wood although copper levels were higher than toxic thresholds previously identified. It was hypothesized that the copper in leachate from ACQ-treated wood may be coordinated with monoethanolamine and/or lignin-based ligands and that this may result in poorer performance against basidiospores. In this study, electron paramagnetic resonance spectroscopy was used to determine the form of copper in leachates from ACQ, micronized copper quat (MCQ), and copper- sulfate-treated wood. Leachates from ACQ-treated wood contained at least some degree of coordination with a nitrogen- and oxygen-containing ligand, probably monoethanolamine. This was not detected in leachates from MCQ and copper-sulfate-treated wood. These leachates were further evaluated for their ability to inhibit germination of Tyromyces palustris basidiospores. At low concentrations of copper, the CuSO4 and MCQ leachates were more effective than the ACQ leachate. At high concentrations CuSO4 and MCQ, leachates prevented germination in all samples, whereas ACQ leachates prevented germination in all but one sample. Keywords:

@article{
 title = {3-Rhoda-1,2-diazacyclopentanes: A Series of Novel Metallacycle Complexes Derived From C-N Functionalization of Ethylene.},
 type = {article},
 year = {2014},
 keywords = {Electronic Structure,Organometallic Chemistry},
 pages = {13345-55},
 volume = {20},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/25169120},
 month = {10},
 day = {6},
 id = {5cb2abec-d96a-3949-825c-09bbe0de796d},
 created = {2017-09-06T15:15:01.406Z},
 accessed = {2014-10-19},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:25:32.852Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 abstract = {Rh-containing metallacycles, [(TPA)Rh(III) (κ(2) -(C,N)-CH2 CH2 (NR)2 -]Cl; TPA=N,N,N,N-tris(2-pyridylmethyl)amine have been accessed through treatment of the Rh(I) ethylene complex, [(TPA)Rh(η(2) -CH2 CH2 )]Cl ([1]Cl) with substituted diazenes. We show this methodology to be tolerant of electron-deficient azo compounds including azo diesters (RCO2 NNCO2 R; R=Et [3]Cl, R=iPr [4]Cl, R=tBu [5]Cl, and R=Bn [6]Cl) and a cyclic azo diamide: 4-phenyl-1,2,4-triazole-3,5-dione (PTAD), [7]Cl. The latter complex features two ortho-fused ring systems and constitutes the first 3-rhoda-1,2-diazabicyclo[3.3.0]octane. Preliminary evidence suggests that these complexes result from N-N coordination followed by insertion of ethylene into a [Rh]N bond. In terms of reactivity, [3]Cl and [4]Cl successfully undergo ring-opening using p-toluenesulfonic acid, affording the Rh chlorides, [(TPA)Rh(III) (Cl)(κ(1) -(C)-CH2 CH2 (NCO2 R)(NHCO2 R)]OTs; [13]OTs and [14]OTs. Deprotection of [5]Cl using trifluoroacetic acid was also found to give an ethyl substituted, end-on coordinated diazene [(TPA)Rh(III) (κ(2) -(C,N)-CH2 CH2 (NH)2 -](+) [16]Cl, a hitherto unreported motif. Treatment of [16]Cl with acetyl chloride resulted in the bisacetylated adduct [(TPA)Rh(III) (κ(2) -(C,N)-CH2 CH2 (NAc)2 -](+) , [17]Cl. Treatment of [1]Cl with AcNNAc did not give the RhN insertion product, but instead the N,O-chelated complex [(TPA)Rh(I) (κ(2) -(O,N)-CH3 (CO)(NH)(NC(CH3 )(OCHCH2 ))]Cl [23]Cl, presumably through insertion of ethylene into a [Rh]O bond.},
 bibtype = {article},
 author = {Drover, Marcus W and Beh, Daniel W and Kennepohl, Pierre and Love, Jennifer A},
 doi = {10.1002/chem.201403682},
 journal = {Chem. Eur. J.},
 number = {41}
}

Rh-containing metallacycles, [(TPA)Rh(III) (κ(2) -(C,N)-CH2 CH2 (NR)2 -]Cl; TPA=N,N,N,N-tris(2-pyridylmethyl)amine have been accessed through treatment of the Rh(I) ethylene complex, [(TPA)Rh(η(2) -CH2 CH2 )]Cl ([1]Cl) with substituted diazenes. We show this methodology to be tolerant of electron-deficient azo compounds including azo diesters (RCO2 NNCO2 R; R=Et [3]Cl, R=iPr [4]Cl, R=tBu [5]Cl, and R=Bn [6]Cl) and a cyclic azo diamide: 4-phenyl-1,2,4-triazole-3,5-dione (PTAD), [7]Cl. The latter complex features two ortho-fused ring systems and constitutes the first 3-rhoda-1,2-diazabicyclo[3.3.0]octane. Preliminary evidence suggests that these complexes result from N-N coordination followed by insertion of ethylene into a [Rh]N bond. In terms of reactivity, [3]Cl and [4]Cl successfully undergo ring-opening using p-toluenesulfonic acid, affording the Rh chlorides, [(TPA)Rh(III) (Cl)(κ(1) -(C)-CH2 CH2 (NCO2 R)(NHCO2 R)]OTs; [13]OTs and [14]OTs. Deprotection of [5]Cl using trifluoroacetic acid was also found to give an ethyl substituted, end-on coordinated diazene [(TPA)Rh(III) (κ(2) -(C,N)-CH2 CH2 (NH)2 -](+) [16]Cl, a hitherto unreported motif. Treatment of [16]Cl with acetyl chloride resulted in the bisacetylated adduct [(TPA)Rh(III) (κ(2) -(C,N)-CH2 CH2 (NAc)2 -](+) , [17]Cl. Treatment of [1]Cl with AcNNAc did not give the RhN insertion product, but instead the N,O-chelated complex [(TPA)Rh(I) (κ(2) -(O,N)-CH3 (CO)(NH)(NC(CH3 )(OCHCH2 ))]Cl [23]Cl, presumably through insertion of ethylene into a [Rh]O bond.

@article{
 title = {Preface},
 type = {article},
 year = {2013},
 pages = {1-2},
 volume = {257},
 websites = {http://linkinghub.elsevier.com/retrieve/pii/S0010854512002019},
 month = {1},
 id = {a3c9d8ea-1c27-3852-9eea-1a42b528058a},
 created = {2017-09-06T15:14:49.731Z},
 accessed = {2013-07-16},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:20:42.276Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Chen2013},
 private_publication = {false},
 bibtype = {article},
 author = {Chen, Peng and Gamelin, Daniel R. and Kennepohl, Pierre},
 doi = {10.1016/j.ccr.2012.07.011},
 journal = {Coord. Chem. Rev.},
 number = {1}
}

@article{
 title = {Quantification of mobilized copper(II) levels in micronized copper-treated wood by electron paramagnetic resonance (EPR) spectroscopy},
 type = {article},
 year = {2013},
 keywords = {Bioinorganic Chemistry,EPR,Wood Preservation},
 pages = {815-823},
 volume = {67},
 websites = {http://www.degruyter.com/view/j/hfsg.2013.67.issue-7/hf-2012-0136/hf-2012-0136.xml},
 month = {1},
 day = {1},
 id = {6fb26cd2-33cb-3ef2-b35f-327b3f924f2e},
 created = {2017-09-06T15:15:05.314Z},
 accessed = {2014-10-19},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:25:42.192Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 abstract = {Sapwood sawdust from southern pine was treated with micronized copper (MC) under various conditions and the mobilized copper(II) (Cumob) concentrations were determined in the treated wood by electron paramagnetic resonance (EPR) spectroscopy. The spectral parameters for the copper sulfate (CuSO4)-treated sapwood and those of the MC-treated sapwood were very similar. A linear correlation was found between the intensities of copper (Cu) EPR spectra and those of Cu energydispersive X-ray fluorescence spectroscopy in a series of CuSO4-treated sapwood reference samples. Thus, the EPR signal intensities could be reliably correlated to the mass of reacted Cu present using this calibration curve. The amount of the Cumob in sawdust treated by MC suspensions increased during the first 2–3 days after the initial treatment and then reached a maximum during the 7-day monitoring period. In the case of the treatment with MC alone or MC azole, an increased MC concentration led to an elevated amount of Cu (to a maximum of ∼0.23% Cu) solubilized by the sapwood. If the wood was treated with MC quat, the Cumob initially increased, but at higher concentrations the Cumob content decreased, due to the interference by the quat cobiocide on the acid reaction between the wood and the basic Cu carbonate. An examination of commercially-treated wood confirmed the laboratory observations.},
 bibtype = {article},
 author = {Xue, Wei and Kennepohl, Pierre and Ruddick, John N.R.},
 doi = {10.1515/hf-2012-0136},
 journal = {Holzforschung},
 number = {7}
}

Sapwood sawdust from southern pine was treated with micronized copper (MC) under various conditions and the mobilized copper(II) (Cumob) concentrations were determined in the treated wood by electron paramagnetic resonance (EPR) spectroscopy. The spectral parameters for the copper sulfate (CuSO4)-treated sapwood and those of the MC-treated sapwood were very similar. A linear correlation was found between the intensities of copper (Cu) EPR spectra and those of Cu energydispersive X-ray fluorescence spectroscopy in a series of CuSO4-treated sapwood reference samples. Thus, the EPR signal intensities could be reliably correlated to the mass of reacted Cu present using this calibration curve. The amount of the Cumob in sawdust treated by MC suspensions increased during the first 2–3 days after the initial treatment and then reached a maximum during the 7-day monitoring period. In the case of the treatment with MC alone or MC azole, an increased MC concentration led to an elevated amount of Cu (to a maximum of ∼0.23% Cu) solubilized by the sapwood. If the wood was treated with MC quat, the Cumob initially increased, but at higher concentrations the Cumob content decreased, due to the interference by the quat cobiocide on the acid reaction between the wood and the basic Cu carbonate. An examination of commercially-treated wood confirmed the laboratory observations.

@article{
 title = {Dioxygen adducts of rhodium N-heterocyclic carbene complexes},
 type = {article},
 year = {2013},
 keywords = {SSRL},
 pages = {7414},
 volume = {42},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/23440044,http://xlink.rsc.org/?DOI=c3dt32264e},
 month = {5},
 day = {28},
 id = {7fe341aa-01be-3493-8733-a850dacc58bb},
 created = {2017-09-06T15:15:26.895Z},
 accessed = {2013-07-16},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:22:31.609Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Keske2013},
 private_publication = {false},
 abstract = {Rhodium complexes functionalized by N-heterocyclic carbene ligands react with dioxygen to form adducts. Depending on the specifics of the ancillary ligands, oxygen binds to Rh either as a peroxide to form a fully oxidized Rh(III) complex, or as singlet dioxygen in a Rh(I) square planar complex. We have shown through analysis of a series of compounds, some previously published and some novel, that the presence of additional ligands that would support the formation of an octahedral geometry, as typically found with Rh(III) complexes, is critical for formation of the peroxide. In addition, we have demonstrated through DFT studies, that the potential energy surface with regard to the O-O bond length is relatively shallow, which provides a rationale for the distribution of bond lengths observed for apparently similar complexes analyzed by crystallography.},
 bibtype = {article},
 author = {Keske, Eric C. and Zenkina, Olena V and Asadi, Ali and Sun, Hongsui and Praetorius, Jeremy M and Allen, Daryl P and Covelli, Danielle and Patrick, Brian O and Wang, Ruiyao and Kennepohl, Pierre and James, Brian R and Crudden, Cathleen M},
 doi = {10.1039/c3dt32264e},
 journal = {Dalton Trans.},
 number = {20}
}

Rhodium complexes functionalized by N-heterocyclic carbene ligands react with dioxygen to form adducts. Depending on the specifics of the ancillary ligands, oxygen binds to Rh either as a peroxide to form a fully oxidized Rh(III) complex, or as singlet dioxygen in a Rh(I) square planar complex. We have shown through analysis of a series of compounds, some previously published and some novel, that the presence of additional ligands that would support the formation of an octahedral geometry, as typically found with Rh(III) complexes, is critical for formation of the peroxide. In addition, we have demonstrated through DFT studies, that the potential energy surface with regard to the O-O bond length is relatively shallow, which provides a rationale for the distribution of bond lengths observed for apparently similar complexes analyzed by crystallography.

@article{
 title = {Fluorine transfer to alkyl radicals.},
 type = {article},
 year = {2012},
 keywords = {EPR,Westgrid},
 pages = {4026-9},
 volume = {134},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/22320293,http://dx.doi.org/10.1021/ja211679v},
 month = {3},
 day = {7},
 id = {12d96362-19a8-3dce-b062-a0068cad2f23},
 created = {2017-09-06T15:14:48.045Z},
 accessed = {2013-06-18},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-05-23T19:56:40.777Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Rueda-Becerril2012},
 private_publication = {false},
 abstract = {The development of new synthetic technologies for the selective fluorination of organic compounds has increased with the escalating importance of fluorine-containing pharmaceuticals. Traditional methods potentially applicable to drug synthesis rely on the use of ionic forms of fluorine (F(-) or F(+)). Radical methods, while potentially attractive as a complementary approach, are hindered by a paucity of safe sources of atomic fluorine (F(•)). A new approach to alkyl fluorination has been developed that utilizes the reagent N-fluorobenzenesulfonimide as a fluorine transfer agent to alkyl radicals. This approach is successful for a broad range of alkyl radicals, including primary, secondary, tertiary, benzylic, and heteroatom-stabilized radicals. Furthermore, calculations reveal that fluorine-containing ionic reagents are likely candidates for further expansion of this approach to polar reaction media. The use of these reagents in alkyl radical fluorination has the potential to enable powerful new transformations that otherwise would take multiple synthetic steps.},
 bibtype = {article},
 author = {Rueda-Becerril, Montserrat and Sazepin, Claire Chatalova and Leung, Joe Cho Tak and Okbinoglu, Tulin and Kennepohl, Pierre and Paquin, Jean-François and Sammis, Glenn M},
 doi = {10.1021/ja211679v},
 journal = {J. Am. Chem. Soc.},
 number = {9}
}

The development of new synthetic technologies for the selective fluorination of organic compounds has increased with the escalating importance of fluorine-containing pharmaceuticals. Traditional methods potentially applicable to drug synthesis rely on the use of ionic forms of fluorine (F(-) or F(+)). Radical methods, while potentially attractive as a complementary approach, are hindered by a paucity of safe sources of atomic fluorine (F(•)). A new approach to alkyl fluorination has been developed that utilizes the reagent N-fluorobenzenesulfonimide as a fluorine transfer agent to alkyl radicals. This approach is successful for a broad range of alkyl radicals, including primary, secondary, tertiary, benzylic, and heteroatom-stabilized radicals. Furthermore, calculations reveal that fluorine-containing ionic reagents are likely candidates for further expansion of this approach to polar reaction media. The use of these reagents in alkyl radical fluorination has the potential to enable powerful new transformations that otherwise would take multiple synthetic steps.

@article{
 title = {Investigation of copper solubilization and reaction in micronized copper treated wood by electron paramagnetic resonance (EPR) spectroscopy},
 type = {article},
 year = {2012},
 keywords = {Bioinorganic Chemistry,EPR,Wood Preservation},
 pages = {889–895},
 volume = {66},
 websites = {http://www.degruyter.com/view/j/hfsg.2012.66.issue-7/hf.2011.188/hf.2011.188.xml},
 month = {1},
 day = {1},
 id = {6d7bda1f-49db-30ee-84b4-04bbfa1cfc4e},
 created = {2017-09-06T15:14:59.944Z},
 accessed = {2014-10-19},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-12-15T01:28:30.030Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Xue2012},
 private_publication = {false},
 abstract = {The purpose of this study is to compare the reaction chemistry of micronized copper and alkaline copper treatments with wood and to determine how fast copper is solubilised during the reaction between the acidic functionality in wood and the basic copper carbonate (CuCO3). Copper species produced in wood by various treatment methods were analysed by electron paramagnetic resonance (EPR) spectroscopy. The effects of time and solution concentration on the spectral parameters of copper complexes in sawdust treated with copper sulphate solutions were examined, followed by study on the structure and the rate of formation of the copper complexes in sawdust treated with basic CuCO3 suspension The study further attempted to identify a soluble copper species formed in wood during treatment with micronized copper preservatives. Comparisons were made among the fixed copper complexes in wood treated with micronized copper preservatives, copper sulphate solutions, basic CuCO3 suspensions and alkaline copper solution. The results show rapid formation of fixed copper complexes in wood treated with aqueous suspensions of basic CuCO3. These complexes can resist leaching, and they have similar stereochemistry to those formed between wood and copper sulphate. This finding supports the premises that soluble copper is generated during the treatment of sawdust with basic CuCO3, and it can bond to wood cell components by migrating into the cell wall in a manner similar to other soluble copper species. Such copper complexes formed are different from those of alkaline copper treated wood, which can be easily distinguished by EPR.},
 bibtype = {article},
 author = {Xue, Wei and Kennepohl, Pierre and Ruddick, John N.R.},
 doi = {10.1515/hf.2011.188},
 journal = {Holzforschung},
 number = {7}
}

The purpose of this study is to compare the reaction chemistry of micronized copper and alkaline copper treatments with wood and to determine how fast copper is solubilised during the reaction between the acidic functionality in wood and the basic copper carbonate (CuCO3). Copper species produced in wood by various treatment methods were analysed by electron paramagnetic resonance (EPR) spectroscopy. The effects of time and solution concentration on the spectral parameters of copper complexes in sawdust treated with copper sulphate solutions were examined, followed by study on the structure and the rate of formation of the copper complexes in sawdust treated with basic CuCO3 suspension The study further attempted to identify a soluble copper species formed in wood during treatment with micronized copper preservatives. Comparisons were made among the fixed copper complexes in wood treated with micronized copper preservatives, copper sulphate solutions, basic CuCO3 suspensions and alkaline copper solution. The results show rapid formation of fixed copper complexes in wood treated with aqueous suspensions of basic CuCO3. These complexes can resist leaching, and they have similar stereochemistry to those formed between wood and copper sulphate. This finding supports the premises that soluble copper is generated during the treatment of sawdust with basic CuCO3, and it can bond to wood cell components by migrating into the cell wall in a manner similar to other soluble copper species. Such copper complexes formed are different from those of alkaline copper treated wood, which can be easily distinguished by EPR.

@article{
 title = {Synthesis and Characterization of Cationic Rhodium Peroxo Complexes},
 type = {article},
 year = {2012},
 keywords = {SSRL},
 pages = {7306-7315},
 volume = {31},
 websites = {http://pubs.acs.org/doi/abs/10.1021/om300766x},
 month = {11},
 day = {12},
 id = {d52e9f8b-a6c0-388a-9ebf-a5e251e6d873},
 created = {2017-09-06T15:15:28.467Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-12-15T01:28:43.265Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 folder_uuids = {41787eac-57c4-416f-8912-690439b733e0},
 private_publication = {false},
 abstract = {Mononuclear cationic rhodium complexes of dioxygen have been synthesized and characterized. Crystallographic, spectroscopic, and computational results support the conclusion that these complexes are best described as RhIIIO2 2− (rhodium(III) peroxo) complexes, in contrast to recently reported neutral analogues that are best described as RhI1O2 adducts. The nature of the ligand trans to the O2 ligand is crucial in defining the electronic nature of the RhO2 bonding. It is determined that π-donor ligands such as the halidesin conjunction with sufficient steric bulkcan stabilize the formation of RhI1O2 adducts, whereas stronger field ligands lead to the stabilization of asymmetric O2 binding that ultimately favors formation of higher coordinate RhIII peroxo species. The factors that control the relative stabilization of RhIIIO2 2− versus RhI1O2 species are related to the well-established Dewar−Chatt−Duncanson model that has been successfully used to describe the bonding in isoelectronic transition-metal alkene complexes. The specific factors that control the stabilization of one electromer (resonance structure) over another are explored and discussed in detail.},
 bibtype = {article},
 author = {Cipot-Wechsler, Judy and Covelli, Danielle and Praetorius, Jeremy M and Hearns, Nigel and Zenkina, Olena V and Keske, Eric C. and Wang, Ruiyao and Kennepohl, Pierre and Crudden, Cathleen M},
 doi = {10.1021/om300766x},
 journal = {Organometallics},
 number = {21}
}

Mononuclear cationic rhodium complexes of dioxygen have been synthesized and characterized. Crystallographic, spectroscopic, and computational results support the conclusion that these complexes are best described as RhIIIO2 2− (rhodium(III) peroxo) complexes, in contrast to recently reported neutral analogues that are best described as RhI1O2 adducts. The nature of the ligand trans to the O2 ligand is crucial in defining the electronic nature of the RhO2 bonding. It is determined that π-donor ligands such as the halidesin conjunction with sufficient steric bulkcan stabilize the formation of RhI1O2 adducts, whereas stronger field ligands lead to the stabilization of asymmetric O2 binding that ultimately favors formation of higher coordinate RhIII peroxo species. The factors that control the relative stabilization of RhIIIO2 2− versus RhI1O2 species are related to the well-established Dewar−Chatt−Duncanson model that has been successfully used to describe the bonding in isoelectronic transition-metal alkene complexes. The specific factors that control the stabilization of one electromer (resonance structure) over another are explored and discussed in detail.

@article{
 title = {Electronic structure of S-nitrosothiols from sulfur K-edge X-ray absorption spectroscopy},
 type = {article},
 year = {2011},
 keywords = {SSRL},
 pages = {93-97},
 volume = {89},
 websites = {http://www.nrcresearchpress.com/doi/abs/10.1139/V10-083,http://dx.doi.org/10.1139/V10-083},
 month = {2},
 id = {9a83080f-fb4c-368b-a01b-8a858edf0f15},
 created = {2017-09-06T15:15:27.123Z},
 accessed = {2013-05-29},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-05-23T19:56:41.091Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000287150300002},
 source_type = {article},
 private_publication = {false},
 abstract = {Sulfur K-edge X-ray absorption spectroscopy (S K-edge XAS) was applied to investigate the electronic structure of primary and tertiary S-nitrosothiols. Our experimental data, supported by density functional calculations, indicate that changes at C(alpha) affect the S-nitroso group through both inductive and direct orbital effects. Furthermore, our data are consistent with a weakening of the S-N bond in tertiary S-nitrosothiols as compared to their primary S-nitroso analogues. These results support existing computational models and suggest that the reactivity of S-nitrosothiols is not dominated by the electronics of the S-N bond.},
 bibtype = {article},
 author = {Martin-Diaconescu, Vlad and Perepichka, Inna and Bohle, D Scott and Kennepohl, Pierre},
 doi = {10.1139/V10-083},
 journal = {Can. J. Chem.},
 number = {2}
}

Sulfur K-edge X-ray absorption spectroscopy (S K-edge XAS) was applied to investigate the electronic structure of primary and tertiary S-nitrosothiols. Our experimental data, supported by density functional calculations, indicate that changes at C(alpha) affect the S-nitroso group through both inductive and direct orbital effects. Furthermore, our data are consistent with a weakening of the S-N bond in tertiary S-nitrosothiols as compared to their primary S-nitroso analogues. These results support existing computational models and suggest that the reactivity of S-nitrosothiols is not dominated by the electronics of the S-N bond.

@article{
 title = {Oxovanadium(IV) cyclam and bicyclam complexes: potential CXCR4 receptor antagonists.},
 type = {article},
 year = {2010},
 keywords = {Bioinorganic Chemistry,Metal-based drugs,X-ray Absorption Spectroscopy},
 pages = {1122-32},
 volume = {49},
 websites = {http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2818883&tool=pmcentrez&rendertype=abstract},
 month = {2},
 day = {1},
 id = {4f037227-5bc0-3eb7-b9aa-70f718f22031},
 created = {2017-09-06T15:15:09.369Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-29T22:35:34.074Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000273785500042},
 source_type = {article},
 private_publication = {false},
 abstract = {Metal complexation can have a major influence on the antiviral and coreceptor binding properties of cyclam and bicyclam macrocycles. We report the synthesis of the vanadyl cyclam complexes [V((IV))O(cyclam)SO(4)] (1) and [V((IV))O(cyclam)Cl]Cl (2) and the analogous xylylbicyclam sulfato (3) and chlorido (4) complexes. The X-ray crystal structures of 1.1.33CH(3)OH and 2.CH(3)OH.1.5H(2)O show short V=O bonds (1.6093(19) and 1.599(3) A, respectively) with monodentate sulfate H-bonded to ring NH groups for 1, but a long V-Cl bond (2.650(12) A) for 2. The solid-state structures of 3 and 4 were compared to those of 1 and 2 using vanadium K-edge extended X-ray absorption fine structure (EXAFS) data. These suggested that complex 4 was oligomeric and contained bridging chlorido ligands. Electron paramagnetic resonance (EPR) studies suggested that the SO(4)(2-) (from 1) and Cl(-) (from 2) ligands are readily substituted by water in solution, whereas these remain partially bound for the V(IV) xylylbicyclam complexes 3 and 4. The vanadyl xylylbicyclam complexes were highly active against HIV-1 (III(B)) and HIV-2 (ROD) strains with IC(50) values in the range 1-5 microM for 3 and 0.1-0.3 microM for 4; in contrast the vanadyl cyclam complexes 1 and 2 were inactive. The factors that contribute to the activity of these complexes are discussed. Studies of vanadyl cyclam docked into a model of the human CXCR4 coreceptor revealed that the coordination of vanadium to the carboxylate of Asp171 may be accompanied by H-bonding to the macrocycle and an attractive V=O...H interaction involving the backbone Trp195 alpha-carbon proton of CXCR4. In addition, hydrophobic interactions with Trp195 are present. Both ring configuration and the xylyl linker may play roles in determining the higher activity of the bicyclam complexes.},
 bibtype = {article},
 author = {Ross, Allison and Soares, Dinesh C and Covelli, Danielle and Pannecouque, Christophe and Budd, Laura and Collins, Anna and Robertson, Neil and Parsons, Simon and De Clercq, Erik and Kennepohl, Pierre and Sadler, Peter J.},
 doi = {10.1021/ic9020614},
 journal = {Inorg. Chem.},
 number = {3}
}

Metal complexation can have a major influence on the antiviral and coreceptor binding properties of cyclam and bicyclam macrocycles. We report the synthesis of the vanadyl cyclam complexes [V((IV))O(cyclam)SO(4)] (1) and [V((IV))O(cyclam)Cl]Cl (2) and the analogous xylylbicyclam sulfato (3) and chlorido (4) complexes. The X-ray crystal structures of 1.1.33CH(3)OH and 2.CH(3)OH.1.5H(2)O show short V=O bonds (1.6093(19) and 1.599(3) A, respectively) with monodentate sulfate H-bonded to ring NH groups for 1, but a long V-Cl bond (2.650(12) A) for 2. The solid-state structures of 3 and 4 were compared to those of 1 and 2 using vanadium K-edge extended X-ray absorption fine structure (EXAFS) data. These suggested that complex 4 was oligomeric and contained bridging chlorido ligands. Electron paramagnetic resonance (EPR) studies suggested that the SO(4)(2-) (from 1) and Cl(-) (from 2) ligands are readily substituted by water in solution, whereas these remain partially bound for the V(IV) xylylbicyclam complexes 3 and 4. The vanadyl xylylbicyclam complexes were highly active against HIV-1 (III(B)) and HIV-2 (ROD) strains with IC(50) values in the range 1-5 microM for 3 and 0.1-0.3 microM for 4; in contrast the vanadyl cyclam complexes 1 and 2 were inactive. The factors that contribute to the activity of these complexes are discussed. Studies of vanadyl cyclam docked into a model of the human CXCR4 coreceptor revealed that the coordination of vanadium to the carboxylate of Asp171 may be accompanied by H-bonding to the macrocycle and an attractive V=O...H interaction involving the backbone Trp195 alpha-carbon proton of CXCR4. In addition, hydrophobic interactions with Trp195 are present. Both ring configuration and the xylyl linker may play roles in determining the higher activity of the bicyclam complexes.

@article{
 title = {Blueprint XAS: a Matlab-based toolbox for the fitting and analysis of XAS spectra.},
 type = {article},
 year = {2010},
 keywords = {Method Development,Software,X-ray Absorption Spectroscopy},
 pages = {132-7},
 volume = {17},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/20029122,http://dx.doi.org/10.1107/S0909049509046561},
 month = {1},
 id = {321fb677-f5cb-3691-ac6a-77003dcfe8e7},
 created = {2017-09-06T15:15:22.225Z},
 accessed = {2013-07-16},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-29T22:37:06.912Z},
 read = {true},
 starred = {true},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Delgado-Jaime2010a},
 source_type = {Journal Article},
 folder_uuids = {51dd54b6-3357-45f2-ac25-d0a70ed27d18,e286fe6d-1c93-4648-bac6-84acad56f4e5,ebbabfbd-939b-434c-8a89-bba932203a0b},
 private_publication = {false},
 abstract = {Blueprint XAS is a new Matlab-based program developed to fit and analyse X-ray absorption spectroscopy (XAS) data, most specifically in the near-edge region of the spectrum. The program is based on a methodology that introduces a novel background model into the complete fit model and that is capable of generating any number of independent fits with minimal introduction of user bias [Delgado-Jaime & Kennepohl (2010), J. Synchrotron Rad. 17, 119-128]. The functions and settings on the five panels of its graphical user interface are designed to suit the needs of near-edge XAS data analyzers. A batch function allows for the setting of multiple jobs to be run with Matlab in the background. A unique statistics panel allows the user to analyse a family of independent fits, to evaluate fit models and to draw statistically supported conclusions. The version introduced here (v0.2) is currently a toolbox for Matlab. Future stand-alone versions of the program will also incorporate several other new features to create a full package of tools for XAS data processing.},
 bibtype = {article},
 author = {Delgado-Jaime, Mario Ulises and Mewis, Craig Philip and Kennepohl, Pierre},
 doi = {10.1107/S0909049509046561},
 journal = {J. Synchrotron Rad.},
 number = {1}
}

Blueprint XAS is a new Matlab-based program developed to fit and analyse X-ray absorption spectroscopy (XAS) data, most specifically in the near-edge region of the spectrum. The program is based on a methodology that introduces a novel background model into the complete fit model and that is capable of generating any number of independent fits with minimal introduction of user bias [Delgado-Jaime & Kennepohl (2010), J. Synchrotron Rad. 17, 119-128]. The functions and settings on the five panels of its graphical user interface are designed to suit the needs of near-edge XAS data analyzers. A batch function allows for the setting of multiple jobs to be run with Matlab in the background. A unique statistics panel allows the user to analyse a family of independent fits, to evaluate fit models and to draw statistically supported conclusions. The version introduced here (v0.2) is currently a toolbox for Matlab. Future stand-alone versions of the program will also incorporate several other new features to create a full package of tools for XAS data processing.

@article{
 title = {Development and exploration of a new methodology for the fitting and analysis of XAS data.},
 type = {article},
 year = {2010},
 keywords = {Method Development,X-ray Absorption Spectroscopy},
 pages = {119-28},
 volume = {17},
 websites = {http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2816928&tool=pmcentrez&rendertype=abstract,http://dx.doi.org/10.1107/S090904950904655X},
 month = {1},
 publisher = {International Union of Crystallography},
 id = {a3654522-ed2a-3167-91f1-ad6b14e78153},
 created = {2017-09-06T15:15:22.260Z},
 accessed = {2012-10-06},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-29T22:46:48.212Z},
 read = {true},
 starred = {true},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Delgado-Jaime2010},
 source_type = {Journal Article},
 notes = {<b>From Duplicate 2 ( <i>Development and exploration of a new methodology for the fitting and analysis of XAS data.</i> - Delgado-Jaime, Mario Ulises; Kennepohl, Pierre )<br/></b><br/><b>From Duplicate 1 ( <i>Development and exploration of a new methodology for the fitting and analysis of XAS data</i> - Delgado-Jaime, Mario Ulises; Kennepohl, Pierre )<br/></b><br/><b>From Duplicate 1 ( <i>Development and exploration of a new methodology for the fitting and analysis of XAS data</i> - Delgado-Jaime, M U; Kennepohl, Pierre )<br/></b>},
 folder_uuids = {51dd54b6-3357-45f2-ac25-d0a70ed27d18,e286fe6d-1c93-4648-bac6-84acad56f4e5,ebbabfbd-939b-434c-8a89-bba932203a0b},
 private_publication = {false},
 abstract = {A new data analysis methodology for X-ray absorption near-edge spectroscopy (XANES) is introduced and tested using several examples. The methodology has been implemented within the context of a new Matlab-based program discussed in a companion related article [Delgado-Jaime et al. (2010), J. Synchrotron Rad. 17, 132-137]. The approach makes use of a Monte Carlo search method to seek appropriate starting points for a fit model, allowing for the generation of a large number of independent fits with minimal user-induced bias. The applicability of this methodology is tested using various data sets on the Cl K-edge XAS data for tetragonal CuCl(4)(2-), a common reference compound used for calibration and covalency estimation in M-Cl bonds. A new background model function that effectively blends together background profiles with spectral features is an important component of the discussed methodology. The development of a robust evaluation function to fit multiple-edge data is discussed and the implications regarding standard approaches to data analysis are discussed and explored within these examples.},
 bibtype = {article},
 author = {Delgado-Jaime, Mario Ulises and Kennepohl, Pierre},
 doi = {10.1107/S090904950904655X},
 journal = {J. Synchrotron Rad.},
 number = {1}
}

A new data analysis methodology for X-ray absorption near-edge spectroscopy (XANES) is introduced and tested using several examples. The methodology has been implemented within the context of a new Matlab-based program discussed in a companion related article [Delgado-Jaime et al. (2010), J. Synchrotron Rad. 17, 132-137]. The approach makes use of a Monte Carlo search method to seek appropriate starting points for a fit model, allowing for the generation of a large number of independent fits with minimal user-induced bias. The applicability of this methodology is tested using various data sets on the Cl K-edge XAS data for tetragonal CuCl(4)(2-), a common reference compound used for calibration and covalency estimation in M-Cl bonds. A new background model function that effectively blends together background profiles with spectral features is an important component of the discussed methodology. The development of a robust evaluation function to fit multiple-edge data is discussed and the implications regarding standard approaches to data analysis are discussed and explored within these examples.

@article{
 title = {X-ray spectroscopic approaches to the investigation and characterization of photochemical processes. Erratum},
 type = {article},
 year = {2010},
 keywords = {Method Development,Photochemistry,X-ray Absorption Spectroscopy},
 pages = {138-138},
 volume = {17},
 websites = {http://scripts.iucr.org/cgi-bin/paper?S0909049509048237},
 month = {1},
 day = {1},
 id = {82a2d08e-f0c7-3d25-a45b-be2c4937a78f},
 created = {2017-12-19T00:12:58.611Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-29T22:37:09.217Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 bibtype = {article},
 author = {Kennepohl, Pierre and Wasinger, Erik C and DeBeer George, Serena},
 doi = {10.1107/S0909049509048237},
 journal = {Journal of Synchrotron Radiation},
 number = {1}
}

@article{
 title = {Oxovanadium(IV) cyclam and bicyclam complexes: Potential CXCR4 receptor antagonists},
 type = {article},
 year = {2010},
 keywords = {Bioinorganic Chemistry,X-ray Absorption Spectroscopy},
 pages = {1122-1132},
 volume = {49},
 websites = {http://dx.doi.org/10.1021/ic9020614},
 id = {fc653fc9-02e8-3136-8bfc-c7a0bc7cbb37},
 created = {2017-12-19T00:12:58.803Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-12-15T01:28:32.586Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 abstract = {Metal complexation can have a major influence on the antiviral and coreceptor binding properties of cyclam and bicyclam macrocycles. We report the synthesis of the vanadyl cyclam complexes [V((IV))O(cyclam)SO(4)] (1) and [V((IV))O(cyclam)Cl]Cl (2) and the analogous xylylbicyclam sulfato (3) and chlorido (4) complexes. The X-ray crystal structures of 1.1.33CH(3)OH and 2.CH(3)OH.1.5H(2)O show short V=O bonds (1.6093(19) and 1.599(3) A, respectively) with monodentate sulfate H-bonded to ring NH groups for 1, but a long V-Cl bond (2.650(12) A) for 2. The solid-state structures of 3 and 4 were compared to those of 1 and 2 using vanadium K-edge extended X-ray absorption fine structure (EXAFS) data. These suggested that complex 4 was oligomeric and contained bridging chlorido ligands. Electron paramagnetic resonance (EPR) studies suggested that the SO(4)(2-) (from 1) and Cl(-) (from 2) ligands are readily substituted by water in solution, whereas these remain partially bound for the V(IV) xylylbicyclam complexes 3 and 4. The vanadyl xylylbicyclam complexes were highly active against HIV-1 (III(B)) and HIV-2 (ROD) strains with IC(50) values in the range 1-5 microM for 3 and 0.1-0.3 microM for 4; in contrast the vanadyl cyclam complexes 1 and 2 were inactive. The factors that contribute to the activity of these complexes are discussed. Studies of vanadyl cyclam docked into a model of the human CXCR4 coreceptor revealed that the coordination of vanadium to the carboxylate of Asp171 may be accompanied by H-bonding to the macrocycle and an attractive V=O...H interaction involving the backbone Trp195 alpha-carbon proton of CXCR4. In addition, hydrophobic interactions with Trp195 are present. Both ring configuration and the xylyl linker may play roles in determining the higher activity of the bicyclam complexes.},
 bibtype = {article},
 author = {Ross, Allison and Soares, Dinesh C. and Covelli, Danielle and Pannecouque, Christophe and Budd, Laura and Collins, Anna and Robertson, Neil and Parsons, Simon and De Clercq, Erik and Kennepohl, Pierre and Sadler, Peter J.},
 doi = {10.1021/ic9020614},
 journal = {Inorg. Chem.},
 number = {3}
}

Metal complexation can have a major influence on the antiviral and coreceptor binding properties of cyclam and bicyclam macrocycles. We report the synthesis of the vanadyl cyclam complexes [V((IV))O(cyclam)SO(4)] (1) and [V((IV))O(cyclam)Cl]Cl (2) and the analogous xylylbicyclam sulfato (3) and chlorido (4) complexes. The X-ray crystal structures of 1.1.33CH(3)OH and 2.CH(3)OH.1.5H(2)O show short V=O bonds (1.6093(19) and 1.599(3) A, respectively) with monodentate sulfate H-bonded to ring NH groups for 1, but a long V-Cl bond (2.650(12) A) for 2. The solid-state structures of 3 and 4 were compared to those of 1 and 2 using vanadium K-edge extended X-ray absorption fine structure (EXAFS) data. These suggested that complex 4 was oligomeric and contained bridging chlorido ligands. Electron paramagnetic resonance (EPR) studies suggested that the SO(4)(2-) (from 1) and Cl(-) (from 2) ligands are readily substituted by water in solution, whereas these remain partially bound for the V(IV) xylylbicyclam complexes 3 and 4. The vanadyl xylylbicyclam complexes were highly active against HIV-1 (III(B)) and HIV-2 (ROD) strains with IC(50) values in the range 1-5 microM for 3 and 0.1-0.3 microM for 4; in contrast the vanadyl cyclam complexes 1 and 2 were inactive. The factors that contribute to the activity of these complexes are discussed. Studies of vanadyl cyclam docked into a model of the human CXCR4 coreceptor revealed that the coordination of vanadium to the carboxylate of Asp171 may be accompanied by H-bonding to the macrocycle and an attractive V=O...H interaction involving the backbone Trp195 alpha-carbon proton of CXCR4. In addition, hydrophobic interactions with Trp195 are present. Both ring configuration and the xylyl linker may play roles in determining the higher activity of the bicyclam complexes.

@article{
 title = {Abnormal Reactivity of an N-Heterocyclic Carbene (NHC) with a Phosphaalkene: A Route to a 4-Phosphino-Substituted NHC},
 type = {article},
 year = {2009},
 keywords = {DFT,carbenes},
 pages = {9844-9847},
 volume = {48},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/19937891,http://doi.wiley.com/10.1002/anie.200905401},
 month = {12},
 day = {21},
 id = {912b0098-2773-3187-9e00-f1eba5bcf3c4},
 created = {2017-09-06T15:14:51.506Z},
 accessed = {2013-04-05},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-11-20T23:48:25.875Z},
 read = {true},
 starred = {true},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000273452200012},
 source_type = {article},
 private_publication = {false},
 bibtype = {article},
 author = {Bates, Joshua I and Kennepohl, Pierre and Gates, Derek P},
 doi = {10.1002/anie.200905401},
 journal = {Angew. Chem. Int. Ed.},
 number = {52}
}

@article{
 title = {Effects of Hyperconjugation on the Electronic Structure and Photoreactivity of Organic Sulfonyl Chlorides},
 type = {article},
 year = {2009},
 keywords = {DFT,SSRL,X-ray Absorption Spectroscopy,photochemistry,sulfur redox},
 pages = {1038-1044},
 volume = {48},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/19132932,http://pubs.acs.org/doi/abs/10.1021/ic801665f},
 month = {2},
 day = {2},
 institution = {The University of British Columbia, Department of Chemistry, Vancouver, British Columbia V6T 1Z1.},
 id = {eb46010f-7765-39f5-99c8-d1770fad2901},
 created = {2017-09-06T15:14:52.972Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:21:34.472Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Martin-Diaconescu2009},
 private_publication = {false},
 abstract = {The electronic structure of organic sulfonyl compounds of the form RSO(2)G (G = -Cl, -OH, -CH(3)) is investigated to evaluate the effect of aryl R groups on photocleavage of the S-G bond. Sulfur K-edge X-ray absorption spectroscopy (XAS) provides a direct measure of the empty low-lying molecular orbitals in these complexes and, in combination with DFT calculations, a detailed description of the bonding in these compounds. The presence of an aryl group bound to the sulfonyl moiety has a significant impact on the spectroscopy and electronic structure of the site. The analysis suggests that the SCl(sigma*) orbital is significantly affected by mixing with the aryl pi* manifold. This mixing is dependent upon the nature of G and is most pronounced in the sulfonyl chlorides, where the energy of the SCl(sigma*) orbital is lowered by approximately 0.5 eV. The observed mixing is best described as excited-state hyperconjugation of the aryl pi system into the SCl(sigma*) orbital. The magnitude of the effect can be estimated directly from the S K-edge XAS spectra. These results are discussed in relation to the observed photochemistry of RSO(2)Cl, which is significantly enhanced when R = aryl as compared to alkyl substituents.},
 bibtype = {article},
 author = {Martin-Diaconescu, Vlad and Kennepohl, Pierre},
 doi = {10.1021/ic801665f},
 journal = {Inorg. Chem.},
 number = {3}
}

The electronic structure of organic sulfonyl compounds of the form RSO(2)G (G = -Cl, -OH, -CH(3)) is investigated to evaluate the effect of aryl R groups on photocleavage of the S-G bond. Sulfur K-edge X-ray absorption spectroscopy (XAS) provides a direct measure of the empty low-lying molecular orbitals in these complexes and, in combination with DFT calculations, a detailed description of the bonding in these compounds. The presence of an aryl group bound to the sulfonyl moiety has a significant impact on the spectroscopy and electronic structure of the site. The analysis suggests that the SCl(sigma*) orbital is significantly affected by mixing with the aryl pi* manifold. This mixing is dependent upon the nature of G and is most pronounced in the sulfonyl chlorides, where the energy of the SCl(sigma*) orbital is lowered by approximately 0.5 eV. The observed mixing is best described as excited-state hyperconjugation of the aryl pi system into the SCl(sigma*) orbital. The magnitude of the effect can be estimated directly from the S K-edge XAS spectra. These results are discussed in relation to the observed photochemistry of RSO(2)Cl, which is significantly enhanced when R = aryl as compared to alkyl substituents.

@article{
 title = {Influence of oxygenation on the reactivity of ruthenium-thiolato bonds in arene anticancer complexes: insights from XAS and DFT.},
 type = {article},
 year = {2009},
 keywords = {DFT,X-ray Absorption Spectroscopy,metal-based drugs' SSRL},
 pages = {13355-61},
 volume = {131},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/19719101,http://dx.doi.org/10.1021/ja903405z},
 month = {9},
 publisher = {American Chemical Society},
 day = {23},
 id = {6576c082-1a0b-3c7e-80bc-f8c7db6dbbba},
 created = {2017-09-06T15:14:53.025Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:21:32.822Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000270186500047},
 source_type = {article},
 folder_uuids = {78605f3e-c4ca-4aa1-bb27-8876e9306d5d},
 private_publication = {false},
 abstract = {Thiolate ligand oxygenation is believed to activate cytotoxic half-sandwich [(eta(6)-arene)Ru(en)(SR)](+) complexes toward DNA binding. We have made detailed comparisons of the nature of the Ru-S bond in the parent thiolato complexes and mono- (sulfenato) and bis- (sulfinato) oxygenated species including the influence of substituents on the sulfur and arene. Sulfur K-edge XAS indicates that S(3p) donation into the Ru(4d) manifold depends strongly on the oxidation state of the sulfur atom, whereas Ru K-edge data suggest little change at the metal center. DFT results are in agreement with the experimental data and allow a more detailed analysis of the electronic contributions to the Ru-S bond. Overall, the total ligand charge donation to the metal center remains essentially unchanged upon ligand oxygenation, but the origin of the donation differs markedly. In sulfenato complexes, the terminal oxo group makes a large contribution to charge donation and even small electronic changes in the thiolato complexes are amplified upon ligand oxygenation, an observation which carries direct implications for the biological activity of this family of complexes. Details of Ru-S bonding in the mono-oxygenated complexes suggest that these should be most susceptible to ligand exchange, yet only if protonation of the terminal oxo group can occur. The potential consequences of these results for biological activation are discussed.},
 bibtype = {article},
 author = {Sriskandakumar, Thamayanthy and Petzold, Holm and Bruijnincx, Pieter C A and Habtemariam, Abraha and Sadler, Peter J. and Kennepohl, Pierre},
 doi = {10.1021/ja903405z},
 journal = {J. Am. Chem. Soc.},
 number = {37}
}

Thiolate ligand oxygenation is believed to activate cytotoxic half-sandwich [(eta(6)-arene)Ru(en)(SR)](+) complexes toward DNA binding. We have made detailed comparisons of the nature of the Ru-S bond in the parent thiolato complexes and mono- (sulfenato) and bis- (sulfinato) oxygenated species including the influence of substituents on the sulfur and arene. Sulfur K-edge XAS indicates that S(3p) donation into the Ru(4d) manifold depends strongly on the oxidation state of the sulfur atom, whereas Ru K-edge data suggest little change at the metal center. DFT results are in agreement with the experimental data and allow a more detailed analysis of the electronic contributions to the Ru-S bond. Overall, the total ligand charge donation to the metal center remains essentially unchanged upon ligand oxygenation, but the origin of the donation differs markedly. In sulfenato complexes, the terminal oxo group makes a large contribution to charge donation and even small electronic changes in the thiolato complexes are amplified upon ligand oxygenation, an observation which carries direct implications for the biological activity of this family of complexes. Details of Ru-S bonding in the mono-oxygenated complexes suggest that these should be most susceptible to ligand exchange, yet only if protonation of the terminal oxo group can occur. The potential consequences of these results for biological activation are discussed.

@article{
 title = {Redox photochemistry of methionine by sulfur K-edge X-ray absorption spectroscopy: potential implications for cataract formation.},
 type = {article},
 year = {2009},
 keywords = {EPR,SSRL},
 pages = {3577-82},
 volume = {131},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/19226173,http://dx.doi.org/10.1021/ja806946r},
 month = {3},
 day = {18},
 id = {859005ab-273a-35c8-adce-aae63c3f74db},
 created = {2017-09-06T15:15:24.882Z},
 accessed = {2013-07-16},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-05-23T19:56:41.044Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000264792600048},
 source_type = {article},
 private_publication = {false},
 abstract = {The photochemistry of methionine, methionine sulfoxide, and methionine sulfone have been investigated by using sulfur K-edge X-ray absorption spectroscopy to explore the redox photochemical processes under different conditions. Methionine is easily photooxidized to the sulfoxide and the sulfone in the presence of dioxygen. In the absence of oxidant, photoirradiation leads to the one-electron-oxidized cation radical with no further reaction, suggesting that an alternative mechanism for photooxidation of thioethers through direct oxidation is feasible. The photochemistry of methionine sulfoxide allows for independent oxidative and reductive processes. Photoreduction of the sulfoxide leads back to the parent thioether under both aerobic and anaerobic conditions. Photooxidation occurs only under aerobic conditions. In contrast, methionine sulfone is photochemically inert. These results provide new insights into potential photochemical processes that may lead to cataract formation.},
 bibtype = {article},
 author = {Karunakaran-Datt, Anusha and Kennepohl, Pierre},
 doi = {10.1021/ja806946r},
 journal = {J. Am. Chem. Soc.},
 number = {10}
}

The photochemistry of methionine, methionine sulfoxide, and methionine sulfone have been investigated by using sulfur K-edge X-ray absorption spectroscopy to explore the redox photochemical processes under different conditions. Methionine is easily photooxidized to the sulfoxide and the sulfone in the presence of dioxygen. In the absence of oxidant, photoirradiation leads to the one-electron-oxidized cation radical with no further reaction, suggesting that an alternative mechanism for photooxidation of thioethers through direct oxidation is feasible. The photochemistry of methionine sulfoxide allows for independent oxidative and reductive processes. Photoreduction of the sulfoxide leads back to the parent thioether under both aerobic and anaerobic conditions. Photooxidation occurs only under aerobic conditions. In contrast, methionine sulfone is photochemically inert. These results provide new insights into potential photochemical processes that may lead to cataract formation.

@article{
 title = {X-ray spectroscopic approaches to the investigation and characterization of photochemical processes},
 type = {article},
 year = {2009},
 keywords = {SSRL},
 pages = {484-488},
 volume = {16},
 websites = {http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2698811&tool=pmcentrez&rendertype=abstract,http://scripts.iucr.org/cgi-bin/paper?S0909049509021384,http://dx.doi.org/10.1107/S0909049509021384},
 month = {7},
 publisher = {International Union of Crystallography},
 day = {1},
 id = {0068052f-0b12-3546-b720-4cca9f573259},
 created = {2017-09-06T15:15:25.499Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-29T22:46:51.710Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Kennepohl2009},
 private_publication = {false},
 abstract = {Despite a wealth of studies exemplifying the utility of the 2–5 keV X-ray range in speciation and electronic structure elucidation, the exploitation of this energy regime for the study of photochemical processes has not been forthcoming. Herein, a new endstation set-up for in situ photochemical soft X-ray spectroscopy in the 2–5 keV energy region at the Stanford Synchrotron Radiation Lightsource is described for continuous photolysis under anaerobic conditions at both cryogenic and ambient temperatures. Representative examples of this approach are used to demonstrate the potential information content in several fields of study, including organometallic chemistry, biochemistry and materials chemistry. Keywords:},
 bibtype = {article},
 author = {Kennepohl, Pierre and Wasinger, Erik C and DeBeer George, Serena},
 doi = {10.1107/S0909049509021384},
 journal = {J. Synchrotron Rad.},
 number = {4}
}

Despite a wealth of studies exemplifying the utility of the 2–5 keV X-ray range in speciation and electronic structure elucidation, the exploitation of this energy regime for the study of photochemical processes has not been forthcoming. Herein, a new endstation set-up for in situ photochemical soft X-ray spectroscopy in the 2–5 keV energy region at the Stanford Synchrotron Radiation Lightsource is described for continuous photolysis under anaerobic conditions at both cryogenic and ambient temperatures. Representative examples of this approach are used to demonstrate the potential information content in several fields of study, including organometallic chemistry, biochemistry and materials chemistry. Keywords:

@article{
 title = {Assignment of pre-edge features in the Ru K-edge X-ray absorption spectra of organometallic ruthenium complexes},
 type = {article},
 year = {2008},
 keywords = {DFT,SSRL,X-ray Absorption Spectroscopy,olefin metathesis},
 pages = {1059-1065},
 volume = {361},
 websites = {http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2819416&tool=pmcentrez&rendertype=abstract,http://linkinghub.elsevier.com/retrieve/pii/S0020169307004720},
 month = {3},
 day = {1},
 id = {e062cc21-ecf5-3c5c-8ed2-4670f29df678},
 created = {2017-09-06T15:14:47.813Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:16.054Z},
 read = {true},
 starred = {true},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000254858100027},
 source_type = {article},
 folder_uuids = {ebbabfbd-939b-434c-8a89-bba932203a0b},
 private_publication = {false},
 abstract = {The nature of the lowest energy bound-state transition in the Ru K-edge X-ray Absorption Spectra for a series of Grubbs-type ruthenium complexes was investigated. The pre-edge feature was unambiguously assigned as resulting from formally electric dipole forbidden Ru 4d<--1s transitions. The intensities of these transitions are extremely sensitive to the ligand environment and the symmetry of the metal centre. In centrosymmetric complexes the pre-edge is very weak since it is limited by the weak electric quadrupole intensity mechanism. By contrast, upon breaking centrosymmetry, Ru 5p-4d mixing allows for introduction of electric dipole allowed character resulting in a dramatic increase in the pre-edge intensity. The information content of this approach is explored as it relates to complexes of importance in olefin metathesis and its relevance as a tool for the study of reactive intermediates.},
 bibtype = {article},
 author = {Getty, Kendra and Delgado-Jaime, Mario Ulises and Kennepohl, Pierre},
 doi = {10.1016/j.ica.2007.07.029},
 journal = {Inorg. Chim. Acta},
 number = {4}
}

The nature of the lowest energy bound-state transition in the Ru K-edge X-ray Absorption Spectra for a series of Grubbs-type ruthenium complexes was investigated. The pre-edge feature was unambiguously assigned as resulting from formally electric dipole forbidden Ru 4d<--1s transitions. The intensities of these transitions are extremely sensitive to the ligand environment and the symmetry of the metal centre. In centrosymmetric complexes the pre-edge is very weak since it is limited by the weak electric quadrupole intensity mechanism. By contrast, upon breaking centrosymmetry, Ru 5p-4d mixing allows for introduction of electric dipole allowed character resulting in a dramatic increase in the pre-edge intensity. The information content of this approach is explored as it relates to complexes of importance in olefin metathesis and its relevance as a tool for the study of reactive intermediates.

@article{
 title = {N-heterocyclic carbene complexes of Rh: reaction with dioxygen without oxidation.},
 type = {article},
 year = {2008},
 keywords = {DFT,SSRL,X-ray Absorption Spectroscopy,dioxygen complexes},
 pages = {3724-5},
 volume = {130},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/18321109},
 month = {3},
 day = {26},
 id = {9d079bdd-28c6-34cd-b6d8-14af328cc9ab},
 created = {2017-09-06T15:15:29.691Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:23:07.881Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000254173600010},
 source_type = {article},
 private_publication = {false},
 abstract = {The reaction of oxygen with rhodium complexes containing N-heterocyclic carbenes was found to give dioxygen complexes with rare square planar geometries and unusually short O-O bond lengths. Analysis of the bonding in these complexes by Rh L-edge X-ray absorption spectroscopy (XAS), Raman spectroscopy, and DFT calculations provides evidence for a bonding model in which singlet oxygen is bound to a Rh(I) d8 metal complex, rather than the more common Rh(III) d6 peroxo species with octahedral geometry and O-O bond lengths in the 1.4-1.5 A range.},
 bibtype = {article},
 author = {Praetorius, Jeremy M and Allen, Daryl P and Wang, Ruiyao and Webb, Jonathan D and Grein, Friedrich and Kennepohl, Pierre and Crudden, Cathleen M},
 doi = {10.1021/ja7108213},
 journal = {J. Am. Chem. Soc.},
 number = {12}
}

The reaction of oxygen with rhodium complexes containing N-heterocyclic carbenes was found to give dioxygen complexes with rare square planar geometries and unusually short O-O bond lengths. Analysis of the bonding in these complexes by Rh L-edge X-ray absorption spectroscopy (XAS), Raman spectroscopy, and DFT calculations provides evidence for a bonding model in which singlet oxygen is bound to a Rh(I) d8 metal complex, rather than the more common Rh(III) d6 peroxo species with octahedral geometry and O-O bond lengths in the 1.4-1.5 A range.

@article{
 title = {Probing electronic communication in stable benzene-bridged verdazyl diradicals},
 type = {article},
 year = {2007},
 keywords = {EPR},
 pages = {8062-8069},
 volume = {72},
 month = {10},
 id = {3d716cd6-3624-3566-82a6-3569a9caeb3e},
 created = {2017-09-06T15:14:51.745Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-10-19T01:44:52.837Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000249986500032},
 source_type = {article},
 private_publication = {false},
 abstract = {[GRAPHICS] Two benzene-bridged NN'-bis(isopropyl)6-oxoverdazyl diradicals 7a (1,4-benzene-bridged) and 7b (1,3-benzene-bridged) were prepared and studied by an array of physicochemical techniques aimed at elucidating the intramolecular electronic and magnetic coupling between verdazyl chromophores. The very high stability of these diradicals permits comprehensive investigations of their properties for the first time. The UV-vis spectra suggest negligible direct conjugative overlap involving the radical SOMOs, although significant differences in higher energy absorptions suggest that radical orbitals other than the SOMO are likely communicating via the central p-phenylene bridge in 7a. The electrochemical features of the two diradicals are nearly identical; in each derivative, both radicals are oxidized essentially independently while the reductions occur in a stepwise manner with differences of similar to 100mV between the two reductions. EPR and magnetic susceptibility collectively indicate that the para-bridged diradical is weakly antiferromagnetically coupled while the meta analogue is weakly ferromagnetically coupled, in accord with the topology of the substitution pattern on the central benzene ring.},
 bibtype = {article},
 author = {Gilroy, Joe B and McKinnon, Steve D J and Kennepohl, Pierre and Zsombor, Mark S and Ferguson, Michael J and Thompson, Laurence K and Hicks, Robin G},
 doi = {10.1021/jo7014449},
 journal = {J. Org. Chem.},
 number = {21}
}

[GRAPHICS] Two benzene-bridged NN'-bis(isopropyl)6-oxoverdazyl diradicals 7a (1,4-benzene-bridged) and 7b (1,3-benzene-bridged) were prepared and studied by an array of physicochemical techniques aimed at elucidating the intramolecular electronic and magnetic coupling between verdazyl chromophores. The very high stability of these diradicals permits comprehensive investigations of their properties for the first time. The UV-vis spectra suggest negligible direct conjugative overlap involving the radical SOMOs, although significant differences in higher energy absorptions suggest that radical orbitals other than the SOMO are likely communicating via the central p-phenylene bridge in 7a. The electrochemical features of the two diradicals are nearly identical; in each derivative, both radicals are oxidized essentially independently while the reductions occur in a stepwise manner with differences of similar to 100mV between the two reductions. EPR and magnetic susceptibility collectively indicate that the para-bridged diradical is weakly antiferromagnetically coupled while the meta analogue is weakly ferromagnetically coupled, in accord with the topology of the substitution pattern on the central benzene ring.

@article{
 title = {An electronic rationale for observed initiation rates in ruthenium-mediated olefin metathesis: charge donation in phosphine and N-heterocyclic carbene ligands.},
 type = {article},
 year = {2007},
 keywords = {DFT,SSRL,X-ray Absorption Spectroscopy,carbenes,olefin metathesis},
 pages = {15774-6},
 volume = {129},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/18047332},
 month = {12},
 day = {26},
 chapter = {15774},
 id = {2af4b1d4-b450-3874-b3a6-4945d0010372},
 created = {2017-09-06T15:14:52.714Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:21:20.406Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000251974000023},
 source_type = {article},
 language = {English},
 notes = {<b>From Duplicate 1 ( </b><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><b><br/><br/><br/><br/><br/><br/><br/></b><br/><b><br/><i>An electronic rationale for observed initiation rates in ruthenium-mediated olefin metathesis: Charge donation in phosphine and N-heterocyclic carbene ligands</i><br/></b><br/><b><br/><br/><br/><br/><br/><br/><br/></b><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><b>- Getty, Kendra; Delgado-Jaime, Mario Ulises; Kennepohl, Pierre )<br/><br/><br/><br/><br/><br/><br/><br/></b><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><b>From Duplicate 1 ( </b><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><b><br/><br/><br/><br/><br/><br/><br/></b><br/><b><br/><i>An electronic rationale for observed initiation rates in ruthenium-mediated olefin metathesis: Charge donation in phosphine and N-heterocyclic carbene ligands</i><br/></b><br/><b><br/><br/><br/><br/><br/><br/><br/></b><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><br/><b>- Getty, K; Delgado-Jaime, M U; Kennepohl, P )<br/><br/><br/><br/><br/><br/><br/><br/></b><br/><br/><br/><br/><br/><br/><br/><br/>ISI Document Delivery No.: 245YF<br/>Times Cited: 4<br/>Cited Reference Count: 40<br/>Getty, Kendra Delgado-Jaime, Mario Ulises Kennepohl, Pierre<br/>AMER CHEMICAL SOC},
 folder_uuids = {78605f3e-c4ca-4aa1-bb27-8876e9306d5d},
 private_publication = {false},
 abstract = {Ru K-edge XAS data indicate that second generation ruthenium-based olefin metathesis precatalysts (L = N-heterocyclic carbene) possess a more electron-deficient metal center than in the corresponding first generation species (L = tricyclohexylphosphine). This surprising effect is also observed from DFT calculations and provides a simple rationale for the slow phosphine dissociation kinetics previously noted for second-generation metathesis precatalysts.},
 bibtype = {article},
 author = {Getty, Kendra and Delgado-Jaime, Mario Ulises and Kennepohl, Pierre},
 doi = {10.1021/ja0747674},
 journal = {J. Am. Chem. Soc.},
 number = {51}
}

Ru K-edge XAS data indicate that second generation ruthenium-based olefin metathesis precatalysts (L = N-heterocyclic carbene) possess a more electron-deficient metal center than in the corresponding first generation species (L = tricyclohexylphosphine). This surprising effect is also observed from DFT calculations and provides a simple rationale for the slow phosphine dissociation kinetics previously noted for second-generation metathesis precatalysts.

@article{
 title = {Sulfur K-edge XAS as a probe of sulfur-centered radical intermediates.},
 type = {article},
 year = {2007},
 keywords = {DFT,SSRL,X-ray Absorption Spectroscopy,photochemistry,sulfur redox},
 pages = {3034-5},
 volume = {129},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/17319664},
 month = {3},
 day = {21},
 id = {04c88098-f016-319c-b9be-9bd67828cc16},
 created = {2017-09-06T15:14:53.458Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:15.599Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000244896900002},
 source_type = {article},
 folder_uuids = {ebbabfbd-939b-434c-8a89-bba932203a0b},
 private_publication = {false},
 abstract = {Sulfur K-edge XAS is used in the identification and characterization of sulfur based radicals obtained from UV irradiated glutathione. Ground state and time-dependent DFT calculations are used to identify thiyl (RS center dot) and perthiyl (RSS center dot) radical species.},
 bibtype = {article},
 author = {Martin-Diaconescu, Vlad and Kennepohl, Pierre},
 doi = {10.1021/ja0676760},
 journal = {J. Am. Chem. Soc.},
 number = {11}
}

Sulfur K-edge XAS is used in the identification and characterization of sulfur based radicals obtained from UV irradiated glutathione. Ground state and time-dependent DFT calculations are used to identify thiyl (RS center dot) and perthiyl (RSS center dot) radical species.

@article{
 title = {X-ray absorption methods for the determination of Ru–Cl bond covalency in olefin metathesis catalysts: On the normalization of chlorine K-edges in ruthenium complexes},
 type = {article},
 year = {2006},
 keywords = {Electronic Structure,Method Development,Organometallic Chemistry,SSRL,X-ray Absorption Spectroscopy},
 pages = {3042-3047},
 volume = {359},
 websites = {http://linkinghub.elsevier.com/retrieve/pii/S0020169306000260},
 month = {6},
 day = {1},
 id = {6de843f3-b6bc-3e5c-aa6c-cc8bddab583c},
 created = {2017-09-06T15:15:25.660Z},
 accessed = {2011-09-17},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-01-30T06:18:20.612Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000238269600054},
 source_type = {article},
 private_publication = {false},
 abstract = {A systematic approach to quantitative analysis of Cl K-edge XAS spectra in ruthenium complexes is outlined and applied to ruthenium carbene complexes involved in olefin metathesis catalysis. This method is generally well-suited for probing ligand donor contributions into empty transition metal d orbitals, but overlap of the Ru L-2,L-3 edge makes this very difficult in these complexes. A method for removing the Ru L-2,L-3 edges from the Cl K-edge spectrum is developed and tested. The normalization procedure makes use of the well-separated Ru L-2 edge and an appropriate L-3/L-2 branching ratio to unambiguously remove contributions from these edges and allow for accurate normalization of the Cl K-edge spectrum. A generalized background subtraction that accounts for variability over the large energy range involved is also described. The methodology should be general for any similarly overlapping edges, as long as one component of the spin-orbit split metal (L- or M-) edge is unperturbed. The results of this study indicate a substantial difference in Ru-Cl bonding depending on the nature of the catalyst. (c) 2006 Elsevier B.V. All rights reserved.},
 bibtype = {article},
 author = {Delgado-Jaime, Mario Ulises and Conrad, Jay C and Fogg, Deryn E and Kennepohl, Pierre},
 doi = {10.1016/j.ica.2005.12.058},
 journal = {Inorg. Chim. Acta},
 number = {9}
}

A systematic approach to quantitative analysis of Cl K-edge XAS spectra in ruthenium complexes is outlined and applied to ruthenium carbene complexes involved in olefin metathesis catalysis. This method is generally well-suited for probing ligand donor contributions into empty transition metal d orbitals, but overlap of the Ru L-2,L-3 edge makes this very difficult in these complexes. A method for removing the Ru L-2,L-3 edges from the Cl K-edge spectrum is developed and tested. The normalization procedure makes use of the well-separated Ru L-2 edge and an appropriate L-3/L-2 branching ratio to unambiguously remove contributions from these edges and allow for accurate normalization of the Cl K-edge spectrum. A generalized background subtraction that accounts for variability over the large energy range involved is also described. The methodology should be general for any similarly overlapping edges, as long as one component of the spin-orbit split metal (L- or M-) edge is unperturbed. The results of this study indicate a substantial difference in Ru-Cl bonding depending on the nature of the catalyst. (c) 2006 Elsevier B.V. All rights reserved.

@article{
 title = {Variable energy photoelectron spectroscopy: electronic structure and electronic relaxation},
 type = {article},
 year = {2005},
 keywords = {PhD},
 pages = {229-253},
 volume = {249},
 websites = {http://linkinghub.elsevier.com/retrieve/pii/S0010854504000426},
 month = {1},
 id = {30efc1bb-b103-37a8-bd12-c136f82b250e},
 created = {2017-09-06T15:14:50.475Z},
 accessed = {2011-09-17},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-01-27T22:25:50.310Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000226477400012},
 source_type = {article},
 private_publication = {false},
 abstract = {Use of variable photon energy with polarization available from synchrotron radiation has revolutionized the use of photoelectron spectroscopy (PES) in the study of transition metal complexes. The intensity dependence of PES peaks allows their definite assignment, a quantitation of the covalent mixing of the metal and ligand valence orbitals over the entire valence band, and an experimental determination of electronic relaxation. The last effect is the change in electronic structure with ionization, which is found to be large for transition metal complexes. Variable energy PES (VEPES) provides a powerful method to study bonding and its change with ionization and this provides fundamental insight into redox processes in inorganic and bioinorganic chemistry. (C) 2004 Elsevier B.V. All rights reserved.},
 bibtype = {article},
 author = {Solomon, Edward I and Basumallick, Lipika and Chen, Peng and Kennepohl, Pierre},
 doi = {10.1016/j.ccr.2004.02.016},
 journal = {Coord. Chem. Rev.},
 number = {1-2}
}

Use of variable photon energy with polarization available from synchrotron radiation has revolutionized the use of photoelectron spectroscopy (PES) in the study of transition metal complexes. The intensity dependence of PES peaks allows their definite assignment, a quantitation of the covalent mixing of the metal and ligand valence orbitals over the entire valence band, and an experimental determination of electronic relaxation. The last effect is the change in electronic structure with ionization, which is found to be large for transition metal complexes. Variable energy PES (VEPES) provides a powerful method to study bonding and its change with ionization and this provides fundamental insight into redox processes in inorganic and bioinorganic chemistry. (C) 2004 Elsevier B.V. All rights reserved.

@article{
 title = {Spectroscopy of non-heme iron thiolate complexes: insight into the electronic structure of the low-spin active site of nitrile hydratase.},
 type = {article},
 year = {2005},
 keywords = {PhD},
 pages = {1826-36},
 volume = {44},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/15762709},
 month = {3},
 day = {21},
 id = {b01b57c7-a7ee-3d77-9059-0cf0013df52b},
 created = {2017-09-06T15:14:53.804Z},
 accessed = {2013-07-16},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-01-27T22:25:50.906Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000227764700020},
 source_type = {article},
 private_publication = {false},
 abstract = {Detailed spectroscopic and computational studies of the low-spin iron complexes [Fe(III)(S2(Me2)N3 (Pr,Pr))(N3)] (1) and [Fe(III)(S2(Me2)N3 (Pr,Pr))]1+ (2) were performed to investigate the unique electronic features of these species and their relation to the low-spin ferric active sites of nitrile hydratases. Low-temperature UV/vis/NIR and MCD spectra of 1 and 2 reflect electronic structures that are dominated by antibonding interactions of the Fe 3d manifold and the equatorial thiolate S 3p orbitals. The six-coordinate complex 1 exhibits a low-energy S(pi) --> Fe 3d(xy) (approximately 13,000 cm(-1)) charge-transfer transition that results predominantly from the low energy of the singly occupied Fe 3d(xy) orbital, due to pure pi interactions between this acceptor orbital and both thiolate donor ligands in the equatorial plane. The 3d(pi) --> 3d(sigma) ligand-field transitions in this species occur at higher energies (>15,000 cm(-1)), reflecting its near-octahedral symmetry. The Fe 3d(xz,yz) --> Fe 3d(xy) (d(pi) --> d(pi)) transition occurs in the near-IR and probes the Fe(III)-S pi-donor bond; this transition reveals vibronic structure that reflects the strength of this bond (nu(e) approximately 340 cm(-1)). In contrast, the ligand-field transitions of the five-coordinate complex 2 are generally at low energy, and the S(pi) --> Fe charge-transfer transitions occur at much higher energies relative to those in 1. This reflects changes in thiolate bonding in the equatorial plane involving the Fe 3d(xy) and Fe 3d(x2-y2) orbitals. The spectroscopic data lead to a simple bonding model that focuses on the sigma and pi interactions between the ferric ion and the equatorial thiolate ligands, which depend on the S-Fe-S bond angle in each of the complexes. These electronic descriptions provide insight into the unusual S = 1/2 ground spin state of these complexes: the orientation of the thiolate ligands in these complexes restricts their pi-donor interactions to the equatorial plane and enforces a low-spin state. These anisotropic orbital considerations provide some intriguing insights into the possible electronic interactions at the active site of nitrile hydratases and form the foundation for further studies into these low-spin ferric enzymes.},
 bibtype = {article},
 author = {Kennepohl, Pierre and Neese, Frank and Schweitzer, Dirk and Jackson, Henry L and Kovacs, Julie A and Solomon, Edward I},
 doi = {10.1021/ic0487068},
 journal = {Inorg. Chem.},
 number = {6}
}

Detailed spectroscopic and computational studies of the low-spin iron complexes [Fe(III)(S2(Me2)N3 (Pr,Pr))(N3)] (1) and [Fe(III)(S2(Me2)N3 (Pr,Pr))]1+ (2) were performed to investigate the unique electronic features of these species and their relation to the low-spin ferric active sites of nitrile hydratases. Low-temperature UV/vis/NIR and MCD spectra of 1 and 2 reflect electronic structures that are dominated by antibonding interactions of the Fe 3d manifold and the equatorial thiolate S 3p orbitals. The six-coordinate complex 1 exhibits a low-energy S(pi) --> Fe 3d(xy) (approximately 13,000 cm(-1)) charge-transfer transition that results predominantly from the low energy of the singly occupied Fe 3d(xy) orbital, due to pure pi interactions between this acceptor orbital and both thiolate donor ligands in the equatorial plane. The 3d(pi) --> 3d(sigma) ligand-field transitions in this species occur at higher energies (>15,000 cm(-1)), reflecting its near-octahedral symmetry. The Fe 3d(xz,yz) --> Fe 3d(xy) (d(pi) --> d(pi)) transition occurs in the near-IR and probes the Fe(III)-S pi-donor bond; this transition reveals vibronic structure that reflects the strength of this bond (nu(e) approximately 340 cm(-1)). In contrast, the ligand-field transitions of the five-coordinate complex 2 are generally at low energy, and the S(pi) --> Fe charge-transfer transitions occur at much higher energies relative to those in 1. This reflects changes in thiolate bonding in the equatorial plane involving the Fe 3d(xy) and Fe 3d(x2-y2) orbitals. The spectroscopic data lead to a simple bonding model that focuses on the sigma and pi interactions between the ferric ion and the equatorial thiolate ligands, which depend on the S-Fe-S bond angle in each of the complexes. These electronic descriptions provide insight into the unusual S = 1/2 ground spin state of these complexes: the orientation of the thiolate ligands in these complexes restricts their pi-donor interactions to the equatorial plane and enforces a low-spin state. These anisotropic orbital considerations provide some intriguing insights into the possible electronic interactions at the active site of nitrile hydratases and form the foundation for further studies into these low-spin ferric enzymes.

@article{
 title = {X-ray magnetic circular dichroism of Pseudomonas aeruginosa nickel(II) azurin.},
 type = {article},
 year = {2004},
 keywords = {ALS,PDF},
 pages = {5859-66},
 volume = {126},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/15125678},
 month = {5},
 day = {12},
 id = {a37d628b-de02-3e74-b86a-d555c99dd423},
 created = {2017-09-06T15:14:49.183Z},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:21:16.809Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Funk2004},
 private_publication = {false},
 abstract = {We show that X-ray magnetic circular dichroism (XMCD) can be employed to probe the oxidation states and other electronic structural features of nickel active sites in proteins. As a calibration standard, we have measured XMCD and X-ray absorption (XAS) spectra for the nickel(II) derivative of Pseudomonas aeruginosa azurin (NiAz). Our analysis of these spectra confirms that the electronic ground state of NiAz is high-spin (S = 1); we also find that the L(3)-centroid energy is 853.1(1) eV, the branching ratio is 0.722(4), and the magnetic moment is 1.9(4) mu(B). Density functional theory (DFT) calculations on model NiAz structures establish that orbitals 3d(x2-y2) and 3d(z2) are the two valence holes in the high-spin Ni(II) ground state, and in accord with the experimentally determined orbital magnetic moment, the DFT results also demonstrate that both holes are highly delocalized, with 3d(x2-y2) having much greater ligand character.},
 bibtype = {article},
 author = {Funk, Tobias and Kennepohl, Pierre and Di Bilio, Angel J and Wehbi, William a and Young, Anthony T and Friedrich, Stephan and Arenholz, Elke and Gray, Harry B and Cramer, Stephen P},
 doi = {10.1021/ja036218d},
 journal = {J. Am. Chem. Soc.},
 number = {18}
}

We show that X-ray magnetic circular dichroism (XMCD) can be employed to probe the oxidation states and other electronic structural features of nickel active sites in proteins. As a calibration standard, we have measured XMCD and X-ray absorption (XAS) spectra for the nickel(II) derivative of Pseudomonas aeruginosa azurin (NiAz). Our analysis of these spectra confirms that the electronic ground state of NiAz is high-spin (S = 1); we also find that the L(3)-centroid energy is 853.1(1) eV, the branching ratio is 0.722(4), and the magnetic moment is 1.9(4) mu(B). Density functional theory (DFT) calculations on model NiAz structures establish that orbitals 3d(x2-y2) and 3d(z2) are the two valence holes in the high-spin Ni(II) ground state, and in accord with the experimentally determined orbital magnetic moment, the DFT results also demonstrate that both holes are highly delocalized, with 3d(x2-y2) having much greater ligand character.

@book{
 title = {Spectroscopy and Electronic Structure of [FeX4]n-(X=Cl, SR)},
 type = {book},
 year = {2004},
 source = {Comprehensive Coordination Chemistry II},
 keywords = {Electronic Structure},
 volume = {2},
 id = {e75e2d43-551f-3264-ada0-468fd9f95e66},
 created = {2017-09-06T15:15:27.652Z},
 file_attached = {false},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-02-28T16:30:49.222Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 bibtype = {book},
 author = {Kennepohl, Pierre and Solomon, Edward I},
 doi = {10.1016/B0-08-043748-6/01048-3}
}

@article{
 title = {Electronic structure contributions to electron-transfer reactivity in iron-sulfur active sites: 1. Photoelectron spectroscopic determination of electronic relaxation.},
 type = {article},
 year = {2003},
 keywords = {PhD,SSRL,XPS},
 pages = {679-88},
 volume = {42},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/12562181},
 month = {2},
 day = {10},
 id = {7b537be5-75fb-3f8d-b0ec-e1ec88655eb2},
 created = {2017-09-06T15:14:48.630Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2019-06-25T16:41:55.347Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000180870300010},
 source_type = {article},
 private_publication = {false},
 abstract = {Electronic relaxation, the change in molecular electronic structure as a response to oxidation, is investigated in [FeX(4)](2)(-)(,1)(-) (X = Cl, SR) model complexes. Photoelectron spectroscopy, in conjunction with density functional methods, is used to define and evaluate the core and valence electronic relaxation upon ionization of [FeX(4)](2)(-). The presence of intense yet formally forbidden charge-transfer satellite peaks in the PES data is a direct reflection of electronic relaxation. The phenomenon is evaluated as a function of charge redistribution at the metal center (Deltaq(rlx)) resulting from changes in the electronic structure. This charge redistribution is calculated from experimental core and valence PES data using a valence bond configuration interaction (VBCI) model. It is found that electronic relaxation is very large for both core (Fe 2p) and valence (Fe 3d) ionization processes and that it is greater in [Fe(SR)(4)](2)(-) than in [FeCl(4)](2)(-). Similar results are obtained from DFT calculations. The results suggest that, although the lowest-energy valence ionization (from the redox-active molecular orbital) is metal-based, electronic relaxation causes a dramatic redistribution of electron density ( approximately 0.7ē) from the ligands to the metal center corresponding to a generalized increase in covalency over all M-L bonds. The more covalent tetrathiolate achieves a larger Deltaq(rlx) because the LMCT states responsible for relaxation are significantly lower in energy than those in the tetrachloride. The large observed electronic relaxation can make significant contributions to the thermodynamics and kinetics of electron transfer in inorganic systems.},
 bibtype = {article},
 author = {Kennepohl, Pierre and Solomon, Edward I},
 doi = {10.1021/ic020330f},
 journal = {Inorg. Chem.},
 number = {3}
}

Electronic relaxation, the change in molecular electronic structure as a response to oxidation, is investigated in [FeX(4)](2)(-)(,1)(-) (X = Cl, SR) model complexes. Photoelectron spectroscopy, in conjunction with density functional methods, is used to define and evaluate the core and valence electronic relaxation upon ionization of [FeX(4)](2)(-). The presence of intense yet formally forbidden charge-transfer satellite peaks in the PES data is a direct reflection of electronic relaxation. The phenomenon is evaluated as a function of charge redistribution at the metal center (Deltaq(rlx)) resulting from changes in the electronic structure. This charge redistribution is calculated from experimental core and valence PES data using a valence bond configuration interaction (VBCI) model. It is found that electronic relaxation is very large for both core (Fe 2p) and valence (Fe 3d) ionization processes and that it is greater in [Fe(SR)(4)](2)(-) than in [FeCl(4)](2)(-). Similar results are obtained from DFT calculations. The results suggest that, although the lowest-energy valence ionization (from the redox-active molecular orbital) is metal-based, electronic relaxation causes a dramatic redistribution of electron density ( approximately 0.7ē) from the ligands to the metal center corresponding to a generalized increase in covalency over all M-L bonds. The more covalent tetrathiolate achieves a larger Deltaq(rlx) because the LMCT states responsible for relaxation are significantly lower in energy than those in the tetrachloride. The large observed electronic relaxation can make significant contributions to the thermodynamics and kinetics of electron transfer in inorganic systems.

@article{
 title = {Electronic structure contributions to electron-transfer reactivity in iron-sulfur active sites: 3. Kinetics of electron transfer.},
 type = {article},
 year = {2003},
 keywords = {PhD,SSRL,XPS},
 pages = {696-708},
 volume = {42},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/12562183},
 month = {2},
 day = {10},
 id = {d9733c86-9206-3b62-a40c-431c7e392f40},
 created = {2017-09-06T15:14:49.373Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2019-06-25T16:41:55.398Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000180870300012},
 source_type = {article},
 private_publication = {false},
 abstract = {The kinetics of electron transfer for rubredoxins are examined using density functional methods to determine the electronic structure characteristics that influence and allow for fast electron self-exchange in these electron-transport proteins. Potential energy surfaces for [FeX(4)](2-,1-) models confirm that the inner-sphere reorganization energy is inherently small for tetrathiolates ( approximately 0.1 eV), as evidenced by the only small changes in the equilibrium Fe-S bond distance during redox (Deltar(redox) approximately 0.05 A). It is concluded that electronic relaxation and covalency in the reduced state allow for this small in this case relative to other redox couples, such as the tetrachloride. Using a large computational model to include the protein medium surrounding the [Fe(SCys)(4)](2-,1-) active site in Desulfovibrio vulgaris Rubredoxin, the electronic coupling matrix element for electron self-exchange is defined for direct active-site contact (H0(DA)). Simple Beratan-Onuchic model is used to extend coupling over the complete surface of the protein to provide an understanding of probable electron-transfer pathways. Regions of similar coupling properties are grouped together to define a surface coupling map, which reveals that very efficient self-exchange occurs only within 4 sigma-bonds of the active site. Longer-range electron transfer cannot support the fast rates of electron self-exchange observed experimentally. Pathways directly through the two surface cysteinate ligands dominate, but surface-accessible amides hydrogen-bonded to the cysteinates also contribute significantly to the rate of electron self-exchange.},
 bibtype = {article},
 author = {Kennepohl, Pierre and Solomon, Edward I},
 doi = {10.1021/ic0203320},
 journal = {Inorg. Chem.},
 number = {3}
}

The kinetics of electron transfer for rubredoxins are examined using density functional methods to determine the electronic structure characteristics that influence and allow for fast electron self-exchange in these electron-transport proteins. Potential energy surfaces for [FeX(4)](2-,1-) models confirm that the inner-sphere reorganization energy is inherently small for tetrathiolates ( approximately 0.1 eV), as evidenced by the only small changes in the equilibrium Fe-S bond distance during redox (Deltar(redox) approximately 0.05 A). It is concluded that electronic relaxation and covalency in the reduced state allow for this small in this case relative to other redox couples, such as the tetrachloride. Using a large computational model to include the protein medium surrounding the [Fe(SCys)(4)](2-,1-) active site in Desulfovibrio vulgaris Rubredoxin, the electronic coupling matrix element for electron self-exchange is defined for direct active-site contact (H0(DA)). Simple Beratan-Onuchic model is used to extend coupling over the complete surface of the protein to provide an understanding of probable electron-transfer pathways. Regions of similar coupling properties are grouped together to define a surface coupling map, which reveals that very efficient self-exchange occurs only within 4 sigma-bonds of the active site. Longer-range electron transfer cannot support the fast rates of electron self-exchange observed experimentally. Pathways directly through the two surface cysteinate ligands dominate, but surface-accessible amides hydrogen-bonded to the cysteinates also contribute significantly to the rate of electron self-exchange.

@article{
 title = {Electronic structure contributions to electron-transfer reactivity in iron-sulfur active sites: 2. Reduction potentials.},
 type = {article},
 year = {2003},
 keywords = {Bioinorganic Chemistry,Electronic Structure,PhD,SSRL,XPS},
 pages = {689-95},
 volume = {42},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/12562182},
 month = {2},
 day = {10},
 id = {07a861a0-9ddd-3340-be0b-dcdcd157b90f},
 created = {2017-09-06T15:15:26.251Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2019-06-25T16:41:55.439Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000180870300011},
 source_type = {article},
 private_publication = {false},
 abstract = {This study utilizes photoelectron spectroscopy (PES) combined with theoretical methods to determine the electronic structure contributions to the large reduction potential difference between [FeCl(4)](2)(-)(,1)(-) and [Fe(SR)(4)](2)(-)(,1)(-) (DeltaE(0) approximately 1 V). Valence PES data confirm that this effect results from electronic structure differences because there is a similarly large shift in the onset of valence ionization between the two reduced species (DeltaI(vert) = 1.4 +/- 0.3 eV). Specific electronic contributions to DeltaI(vert) have been investigated and defined. Ligand field effects, which are often considered to be of great importance, contribute very little to DeltaI(vert) (DeltaE(LF) < -0.05 eV). By contrast, electronic relaxation, a factor that is often neglected in the analysis of chemical reactivity, strongly affects the valence ionization energies of both species. The larger electronic relaxation in the tetrathiolate allows it to more effectively stabilize the oxidized state and lowers its I(vert) relative to that of the chloride (DeltaE(rlx) = 0.2 eV). The largest contribution to the difference in redox potentials is the much lower effective charge () of the tetrathiolate in the reduced state, which results in a large difference in the energy of the Fe 3d manifold between the two redox couples (DeltaE(Fe)( )(3d) = 1.2 eV). This difference derives from the significantly higher covalency of the iron-thiolate bond, which decreases and significantly lowers its redox potential.},
 bibtype = {article},
 author = {Kennepohl, Pierre and Solomon, Edward I},
 doi = {10.1021/ic0203318},
 journal = {Inorg. Chem.},
 number = {3}
}

This study utilizes photoelectron spectroscopy (PES) combined with theoretical methods to determine the electronic structure contributions to the large reduction potential difference between [FeCl(4)](2)(-)(,1)(-) and [Fe(SR)(4)](2)(-)(,1)(-) (DeltaE(0) approximately 1 V). Valence PES data confirm that this effect results from electronic structure differences because there is a similarly large shift in the onset of valence ionization between the two reduced species (DeltaI(vert) = 1.4 +/- 0.3 eV). Specific electronic contributions to DeltaI(vert) have been investigated and defined. Ligand field effects, which are often considered to be of great importance, contribute very little to DeltaI(vert) (DeltaE(LF) < -0.05 eV). By contrast, electronic relaxation, a factor that is often neglected in the analysis of chemical reactivity, strongly affects the valence ionization energies of both species. The larger electronic relaxation in the tetrathiolate allows it to more effectively stabilize the oxidized state and lowers its I(vert) relative to that of the chloride (DeltaE(rlx) = 0.2 eV). The largest contribution to the difference in redox potentials is the much lower effective charge () of the tetrathiolate in the reduced state, which results in a large difference in the energy of the Fe 3d manifold between the two redox couples (DeltaE(Fe)( )(3d) = 1.2 eV). This difference derives from the significantly higher covalency of the iron-thiolate bond, which decreases and significantly lowers its redox potential.

@article{
 title = {A Multiplet Analysis of Fe K-Edge 1s → 3d Pre-Edge Features of Iron Complexes},
 type = {article},
 year = {1997},
 keywords = {PhD,SSRL,X-ray Absorption Spectroscopy,methodology},
 pages = {6297-6314},
 volume = {119},
 websites = {http://pubs.acs.org/doi/abs/10.1021/ja964352a},
 month = {7},
 id = {9bb49f56-26e6-3b3d-bdbb-da14eed82da6},
 created = {2017-09-06T15:15:26.316Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-22T14:44:15.157Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:A1997XJ83300011},
 source_type = {article},
 folder_uuids = {a7bb438c-f222-4fd5-9b7a-741bc62dd04b,ebbabfbd-939b-434c-8a89-bba932203a0b},
 private_publication = {false},
 abstract = {X-ray absorption Fe-K edge data on ferrous and ferric model complexes have been studied to establish a detailed understanding of the 1s --> 3d pre-edge feature and its sensitivity to the electronic structure of the iron site. The energy position and splitting, and intensity distribution, of the pre-edge feature were found to vary systematically with spin state, oxidation state, geometry, and bridging ligation (for binuclear complexes). A methodology for interpreting the energy splitting and intensity distribution of the 1s --> 3d pre-edge features was developed for high-spin ferrous and ferric complexes in octahedral, tetrahedral, and square pyramidal environments and low-spin ferrous and ferric complexes in octahedral environments. In each case, the allowable many-electron excited states were determined using ligand field theory. The energies of the excited states were calculated and compared to the energy splitting in the 1s --> 3d pre-edge features. The relative intensities of electric quadrupole transitions into the many-electron excited states were obtained and compared to the intensity pattern of the pre-edge feature. The effects of distorting the octahedral iron site to tetrahedral and square pyramidal geometries were analyzed. The contributions to the pre-edge intensity from both electric quadrupole and electric dipole (from 3d-4p mixing) intensity mechanisms were established for these distorted cases; the amount of 4p character and its distribution over the many-electron final states were experimentally estimated and compared to theoretical predictions from density functional calculations. The methodology was also applied to binuclear complexes, and a clear marker for the presence of a mu-oxo Fe-O-Fe bridge was established. General trends in 3d-4p mixing are developed and discussed for a series of geometries and oxidation states of Fe complexes. The results presented should further aid in the interpretation of the Is - 3d pre-edge region of iron complexes and non-heme iron enzymes.},
 bibtype = {article},
 author = {Westre, Tami E and Kennepohl, Pierre and DeWitt, Jane G and Hedman, Britt and Hodgson, Keith O and Solomon, Edward I},
 doi = {10.1021/ja964352a},
 journal = {J. Am. Chem. Soc.},
 number = {27}
}

X-ray absorption Fe-K edge data on ferrous and ferric model complexes have been studied to establish a detailed understanding of the 1s --> 3d pre-edge feature and its sensitivity to the electronic structure of the iron site. The energy position and splitting, and intensity distribution, of the pre-edge feature were found to vary systematically with spin state, oxidation state, geometry, and bridging ligation (for binuclear complexes). A methodology for interpreting the energy splitting and intensity distribution of the 1s --> 3d pre-edge features was developed for high-spin ferrous and ferric complexes in octahedral, tetrahedral, and square pyramidal environments and low-spin ferrous and ferric complexes in octahedral environments. In each case, the allowable many-electron excited states were determined using ligand field theory. The energies of the excited states were calculated and compared to the energy splitting in the 1s --> 3d pre-edge features. The relative intensities of electric quadrupole transitions into the many-electron excited states were obtained and compared to the intensity pattern of the pre-edge feature. The effects of distorting the octahedral iron site to tetrahedral and square pyramidal geometries were analyzed. The contributions to the pre-edge intensity from both electric quadrupole and electric dipole (from 3d-4p mixing) intensity mechanisms were established for these distorted cases; the amount of 4p character and its distribution over the many-electron final states were experimentally estimated and compared to theoretical predictions from density functional calculations. The methodology was also applied to binuclear complexes, and a clear marker for the presence of a mu-oxo Fe-O-Fe bridge was established. General trends in 3d-4p mixing are developed and discussed for a series of geometries and oxidation states of Fe complexes. The results presented should further aid in the interpretation of the Is - 3d pre-edge region of iron complexes and non-heme iron enzymes.

@article{
 title = {Structural and Functional Aspects of Metal Sites in Biology},
 type = {article},
 year = {1996},
 keywords = {Bioinorganic Chemistry,PhD,Review},
 pages = {2239-2314},
 volume = {96},
 websites = {http://pubs.acs.org/doi/abs/10.1021/cr9500390},
 month = {1},
 id = {cfd62e52-c9f3-3808-8314-9c32c890a853},
 created = {2017-09-06T15:15:26.119Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2018-01-27T22:25:50.317Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:A1996VT05300002},
 source_type = {article},
 private_publication = {false},
 bibtype = {article},
 author = {Holm, Richard H and Kennepohl, Pierre and Solomon, Edward I},
 doi = {10.1021/cr9500390},
 journal = {Chem. Rev.},
 number = {7}
}

@article{
 title = {Structural and functional aspects of metal sites in biology},
 type = {article},
 year = {1996},
 volume = {96},
 id = {42445060-81b4-37aa-b703-9aa7a4d97935},
 created = {2017-09-06T15:15:27.867Z},
 file_attached = {false},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2020-04-29T22:35:34.606Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {false},
 hidden = {false},
 private_publication = {false},
 bibtype = {article},
 author = {Holm, R.H. and Kennepohl, P. and Solomon, E.I.},
 journal = {Chem. Rev.},
 number = {7}
}

@article{
 title = {Reduction and Aggregation of Silver Ions at the Surface of Colloidal Silica},
 type = {article},
 year = {1994},
 keywords = {BSc},
 pages = {9619-9625},
 volume = {98},
 websites = {http://pubs.acs.org/doi/abs/10.1021/j100089a042},
 month = {9},
 id = {4c6eea67-7ea7-365e-bc53-7d0f9d1d44b6},
 created = {2017-09-06T15:14:49.609Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:20:50.282Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:A1994PH55900042},
 source_type = {article},
 private_publication = {false},
 abstract = {The reduction of silver ions at the surface of 40 Angstrom colloidal silica particles at pH 9 has been studied using the pulse radiolysis technique. The rate of reaction of e(aq)(-) with Ag+ increases linearly with an increase in the Ag+/SiO2 ratio until a ratio of 12:1 is reached. At this loading the reaction becomes independent of the silver concentration at the particle surface. Ag-0 and Ag-2(+), the first products of silver ion reduction in aqueous solution, have been identified by their absorption spectra as the primary species formed by the reduction of silver ions at the surface of SiO2. Within the time window of the experiments (less than or equal to 200 mu s) there is no evidence of larger silver cluster formations (e.g., Ag-4(2+)) that are formed under identical conditions in the absence of silica. Evidently, the silica surface stabilizes the Ag-2(+) cation. Irradiation of Ag+/SiO2 solutions with trains of electron pulses leads to the formation of two small silver clusters exhibiting spectral bands at 290 and 330 nm and the conventional colloidal particle with its. band at similar to 400 nm.. These clusters are stable-in the presence of oxygen for at least several weeks. Addition of redox active and reducing agents confirmed that the three spectral bands originate from three different clusters.},
 bibtype = {article},
 author = {Lawless, Darren and Kapoor, Sudhir and Kennepohl, Pierre and Meisel, Dan and Serpone, Nick},
 doi = {10.1021/j100089a042},
 journal = {J. Phys. Chem.},
 number = {38}
}

The reduction of silver ions at the surface of 40 Angstrom colloidal silica particles at pH 9 has been studied using the pulse radiolysis technique. The rate of reaction of e(aq)(-) with Ag+ increases linearly with an increase in the Ag+/SiO2 ratio until a ratio of 12:1 is reached. At this loading the reaction becomes independent of the silver concentration at the particle surface. Ag-0 and Ag-2(+), the first products of silver ion reduction in aqueous solution, have been identified by their absorption spectra as the primary species formed by the reduction of silver ions at the surface of SiO2. Within the time window of the experiments (less than or equal to 200 mu s) there is no evidence of larger silver cluster formations (e.g., Ag-4(2+)) that are formed under identical conditions in the absence of silica. Evidently, the silica surface stabilizes the Ag-2(+) cation. Irradiation of Ag+/SiO2 solutions with trains of electron pulses leads to the formation of two small silver clusters exhibiting spectral bands at 290 and 330 nm and the conventional colloidal particle with its. band at similar to 400 nm.. These clusters are stable-in the presence of oxygen for at least several weeks. Addition of redox active and reducing agents confirmed that the three spectral bands originate from three different clusters.

@inproceedings{
 title = {Reduction and Aggregation of Silver in Aqueous Gelatin and Silica Suspensions},
 type = {inproceedings},
 year = {1994},
 keywords = {BSc},
 pages = {57-60},
 id = {9667173a-5b54-3120-ac92-81f1be31867e},
 created = {2017-09-06T15:14:50.156Z},
 file_attached = {false},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:14:50.156Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:A1994BC23W00022},
 source_type = {inproceedings},
 notes = {47th Annual Conference/ICPS 94 - The Physics and Chemistry of Imaging<br/>Systems of the Society-for-Imaging-Science-and-Technology, ROCHESTER,<br/>NY, MAY 15-20, 1994},
 private_publication = {false},
 bibtype = {inproceedings},
 author = {Kapoor, Sudhir and Lawless, Darren and Kennepohl, Pierre and Meisel, Dan},
 booktitle = {ICPS `94: The Physics and Chemistry os Imaging Systems}
}

@article{
 title = {Reduction and Aggregation of Silver Ions in Aqueous Gelatin Solutions},
 type = {article},
 year = {1994},
 keywords = {BSc},
 pages = {3018-3022},
 volume = {10},
 websites = {http://pubs.acs.org/doi/abs/10.1021/la00021a026},
 month = {9},
 id = {86fa5700-c58d-30b1-a115-cbde25e81a3f},
 created = {2017-09-06T15:14:53.715Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:42:35.907Z},
 read = {true},
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 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:A1994PH96400026},
 source_type = {article},
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 abstract = {Radiolytic reduction of silver ions and the subsequent formation of silver clusters were studied in aqueous gelatin solutions and are compared with the parallel processes in aqueous solutions. The presence of gelatin in the solution affects the early processes, via complexation of Ag+ ions with the amino acid moieties of the gelatin. The ratio of Ag+ to gelatin chains predetermines the kinetic consequences to the agglomeration processes. This ratio may accelerate or inhibit any of the processes that involve silver ions (reduction as well as growth). The complexation reduces somewhat the rate of reduction by hydrated electrons. However, when all the ions are complexed to the gelatin, the agglomeration may become very fast; at the extreme the agglomeration rate is determined by the rate of reduction. Some of the small Ag-n(m+) bind to the gelatin stronger than Ag+ ions. Excess silver ions enhance the stability of smaller transient clusters in the presence of gelatin. Three long-lived aggregates of different sizes are stabilized by the gelatin upon complete reduction of the silver ions.},
 bibtype = {article},
 author = {Kapoor, Sudhir and Lawless, Darren and Kennepohl, Pierre and Meisel, Dan and Serpone, Nick},
 doi = {10.1021/la00021a026},
 journal = {Langmuir},
 number = {9}
}

Radiolytic reduction of silver ions and the subsequent formation of silver clusters were studied in aqueous gelatin solutions and are compared with the parallel processes in aqueous solutions. The presence of gelatin in the solution affects the early processes, via complexation of Ag+ ions with the amino acid moieties of the gelatin. The ratio of Ag+ to gelatin chains predetermines the kinetic consequences to the agglomeration processes. This ratio may accelerate or inhibit any of the processes that involve silver ions (reduction as well as growth). The complexation reduces somewhat the rate of reduction by hydrated electrons. However, when all the ions are complexed to the gelatin, the agglomeration may become very fast; at the extreme the agglomeration rate is determined by the rate of reduction. Some of the small Ag-n(m+) bind to the gelatin stronger than Ag+ ions. Excess silver ions enhance the stability of smaller transient clusters in the presence of gelatin. Three long-lived aggregates of different sizes are stabilized by the gelatin upon complete reduction of the silver ions.

@article{
 title = {On the usage of turnover numbers and quantum yields in heterogeneous photocatalysis},
 type = {article},
 year = {1993},
 keywords = {BSc},
 pages = {11-16},
 volume = {73},
 websites = {http://linkinghub.elsevier.com/retrieve/pii/1010603093800277},
 month = {6},
 id = {cf03a036-ce61-3ca0-8f64-ddb5dfe3aaa8},
 created = {2017-09-06T15:14:50.817Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:21:55.603Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Serpone1993},
 private_publication = {false},
 abstract = {This paper discusses two issues which have led to, and continue to cause, confusion in the heterogeneous photochemical literature: (i) turnover numbers (turnover rates, turnover frequencies) and (ii) quantum yields. Attention is called to the use of these two parameters when describing the catalytic activity of a photocatalyst on the one hand and the efficiency of a photon on the other. A parameter is defined (relative photonic efficiency) and a simple method is proposed which provides a means of validating data between experiments and between laboratories. In addition, the process efficiency can be assessed and the photocatalytic activity of different materials and a given photocatalyst material from various sources can be validated.},
 bibtype = {article},
 author = {Serpone, Nick and Terzian, Rita and Lawless, Darren and Kennepohl, Pierre and Sauvé, Geneviève},
 doi = {10.1016/1010-6030(93)80027-7},
 journal = {J. Photochem. Photobiol. A},
 number = {1}
}

This paper discusses two issues which have led to, and continue to cause, confusion in the heterogeneous photochemical literature: (i) turnover numbers (turnover rates, turnover frequencies) and (ii) quantum yields. Attention is called to the use of these two parameters when describing the catalytic activity of a photocatalyst on the one hand and the efficiency of a photon on the other. A parameter is defined (relative photonic efficiency) and a simple method is proposed which provides a means of validating data between experiments and between laboratories. In addition, the process efficiency can be assessed and the photocatalytic activity of different materials and a given photocatalyst material from various sources can be validated.

@article{
 title = {Thin films of non-stoichiometric perovskites as potential oxygen sensors},
 type = {article},
 year = {1993},
 keywords = {BSc},
 pages = {272-275},
 volume = {13},
 websites = {http://linkinghub.elsevier.com/retrieve/pii/092540059385379O},
 month = {5},
 id = {6977eded-2e57-37fa-9cf2-21a0f0423dcf},
 created = {2017-09-06T15:15:26.518Z},
 accessed = {2011-11-03},
 file_attached = {true},
 profile_id = {8c5f55f8-b69e-30e2-981b-01f0d567bbfe},
 last_modified = {2017-09-06T15:22:21.839Z},
 read = {true},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:A1993LM16400071},
 source_type = {article},
 notes = {4TH INTERNATIONAL MEETING ON CHEMICAL SENSORS, TOKYO, JAPAN, SEP 13-17,<br/>1992},
 private_publication = {false},
 abstract = {Thin films of non-stoichiometric perovskites of general formula ABO2.5+x have been grown, on sapphire substrates, by the technique of pulsed laser ablation/deposition. The structural properties of the films upon exposure to atmospheres of various oxygen pressures, at elevated temperatures, have been determined by X-ray diffraction; they show changes which correlate with those found for bulk powder samples. For the material SrFeO2.5+x, With 0 less-than-or-equal-to x less-than-or-equal-to 0.5, pressure-composition isotherms reveal several pressure ranges over which structural changes occur. By monitoring the changes in physical properties that accompany the bulk chemical changes, this system can be exploited to provide a thin-film sensor, the structural changes of which are specific to oxygen.},
 bibtype = {article},
 author = {Post, Michael L and Sanders, Brian W and Kennepohl, Pierre},
 doi = {10.1016/0925-4005(93)85379-O},
 journal = {Sensors and Actuators B: Chemical},
 number = {1-3}
}

Thin films of non-stoichiometric perovskites of general formula ABO2.5+x have been grown, on sapphire substrates, by the technique of pulsed laser ablation/deposition. The structural properties of the films upon exposure to atmospheres of various oxygen pressures, at elevated temperatures, have been determined by X-ray diffraction; they show changes which correlate with those found for bulk powder samples. For the material SrFeO2.5+x, With 0 less-than-or-equal-to x less-than-or-equal-to 0.5, pressure-composition isotherms reveal several pressure ranges over which structural changes occur. By monitoring the changes in physical properties that accompany the bulk chemical changes, this system can be exploited to provide a thin-film sensor, the structural changes of which are specific to oxygen.