An expanded cavity hexaamine cage for copper(ii)

Abstract

The crystal structure of the bicyclic hexaamine complex [Cu(fac-Me₅-tricosane-N₆)](ClO₄)₂·H₂O (fac-Me₅-tricosane-N₆ = facial-1,5,9,13,20-pentamethyl-3,7,11,15,18,22-hexaazabicyclo[7.7.7]tricosane) at 100 K defines an apparently tetragonally compressed octahedral geometry, which is attributed to a combination of dynamic interconversion and static disorder between two tetragonally elongated structures sharing a common short axis. This structure is fluxional at 60 K and above as shown by EPR spectroscopy. Aqueous cyclic voltammetry reveals that a remarkably stable Cu^I form of the complex is stabilised by the encapsulating nature of the expanded cage ligand.