Counsell, A.J.Yu, M.Shi, M.Jones, A.T.Batten, J.M.Turner, P.Todd, M.H.Rutledge, P.J.2025-12-182025-12-182021Dalton Transactions, 2021; 50(11):3931-39421477-92261477-9234https://hdl.handle.net/11541.2/147992Data source: Supplementary information, https://doi.org/10.1039/D0DT03736BThe coordination chemistry of N-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 of N-propargyl cyclams and related compounds in the creation of diversely functionalised cyclam derivatives via copper-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 demonstrated via a 'tetra-click' reaction with benzyl azide, and the copper-binding behaviour of the resulting tetra-triazole ligand is characterised spectroscopically.enCopyright 2021 Royal Society of Chemistrycopper (II)N-propargylcyclamligandsJournal article10.1039/d0dt03736b2-s2.0-85103067071