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Copper(II) Complexes of N-Propargyl Cyclam Ligands Reveal a Range of Coordination Modes and Colours, and Unexpected Reactivity

submitted on 01.07.2020, 02:44 and posted on 02.07.2020, 08:07 by Andrew Counsell, Mingfeng Yu, Mengying Shi, Angus Jones, James M. Batten, Peter Turner, Matthew Todd, Peter Rutledge

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 demonstrated via a ‘tetra-click’ reaction with benzyl azide, and the copper-binding behaviour of the resulting tetra-triazole ligand is characterised spectroscopically.


Australian Research Council Discovery Project DP120104035


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The University of Sydney



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Declaration of Conflict of Interest

The authors have no conflict of interest to declare.