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

preprint
submitted on 01.07.2020 and posted on 02.07.2020 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.

Funding

Australian Research Council Discovery Project DP120104035

History

Email Address of Submitting Author

peter.rutledge@sydney.edu.au

Institution

The University of Sydney

Country

Australia

ORCID For Submitting Author

0000-0002-0767-5196

Declaration of Conflict of Interest

The authors have no conflict of interest to declare.

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