Copper(ii) complexes ofN-propargyl cyclam ligands reveal a range of coordination modes and colours, and unexpected reactivity. Counsell, A. J., Yu, M., Shi, M., Jones, A. T., Batten, J. M., Turner, P., Todd, M. H., & Rutledge, P. J. Dalton Transactions, 50(11):3931–3942, 2021. Publisher: Royal Society of Chemistry
doi  abstract   bibtex   
The coordination chemistry ofN-functionalised cyclam ligands has a rich history, yet cyclam derivatives with pendant alkynes are largely unexplored. This is despite the significant potential and burgeoning application ofN-propargyl cyclams and related compounds in the creation of diversely functionalised cyclam derivativesviacopper-catalysed azide-alkyne ‘click’ reactions. Herein we describe single crystal X-ray diffraction and spectroscopic investigations of the coordination chemistry of copper(ii) complexes of cyclam derivatives with between 1 and 4 pendant alkynes. The crystal structures of these copper complexes unexpectedly reveal a range of coordination modes, and the surprising occurrence of five unique complexes within a single recrystallisation of the tetra-N-propargyl cyclam ligand. One of these species exhibits weak intramolecular copper-alkyne coordination, and another is formed by a surprising intramolecular copper-mediated hydroalkoxylation reaction with the solvent methanol, transforming one of the pendant alkynes to an enol ether. Multiple functionalisation of the tetra-N-propargyl ligand is demonstratedviaa ‘tetra-click’ reaction with benzyl azide, and the copper-binding behaviour of the resulting tetra-triazole ligand is characterised spectroscopically.
@article{counsell_copperii_2021,
	title = {Copper(ii) complexes {ofN}-propargyl cyclam ligands reveal a range of coordination modes and colours, and unexpected reactivity},
	volume = {50},
	issn = {14779234},
	doi = {10.1039/d0dt03736b},
	abstract = {The coordination chemistry ofN-functionalised cyclam ligands has a rich history, yet cyclam derivatives with pendant alkynes are largely unexplored. This is despite the significant potential and burgeoning application ofN-propargyl cyclams and related compounds in the creation of diversely functionalised cyclam derivativesviacopper-catalysed azide-alkyne ‘click’ reactions. Herein we describe single crystal X-ray diffraction and spectroscopic investigations of the coordination chemistry of copper(ii) complexes of cyclam derivatives with between 1 and 4 pendant alkynes. The crystal structures of these copper complexes unexpectedly reveal a range of coordination modes, and the surprising occurrence of five unique complexes within a single recrystallisation of the tetra-N-propargyl cyclam ligand. One of these species exhibits weak intramolecular copper-alkyne coordination, and another is formed by a surprising intramolecular copper-mediated hydroalkoxylation reaction with the solvent methanol, transforming one of the pendant alkynes to an enol ether. Multiple functionalisation of the tetra-N-propargyl ligand is demonstratedviaa ‘tetra-click’ reaction with benzyl azide, and the copper-binding behaviour of the resulting tetra-triazole ligand is characterised spectroscopically.},
	number = {11},
	journal = {Dalton Transactions},
	author = {Counsell, Andrew J. and Yu, Mingfeng and Shi, Mengying and Jones, Angus T. and Batten, James M. and Turner, Peter and Todd, Matthew H. and Rutledge, Peter J.},
	year = {2021},
	pmid = {33635937},
	note = {Publisher: Royal Society of Chemistry},
	pages = {3931--3942},
}

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