Cu₆Na₂- and Cu₁₁Na₄-silsesquioxane/2,2'-biquinoline clusters: unique structure and electrochemical and catalytic...

Two unusual ionic complexes have been prepared via the self-assembly of coppersodiumsilsesquioxane in the presence of 2,2'-biquinoline. The compounds represent an intriguing redistribution of copper ions between silsesquioxane and 2,2'-biquinoline ligands, resulting in the formation of a dianionic (Cu₄Na₂ or Cu₉Na₄) cage-like silsesquioxane decorated by two Cu⁺(bq)₂ species. Electrochemical studies and initial testing in the hydrogen evolution reaction (HER) demonstrate that these complexes can be immobilised on carbon fibre paper and applied as electrode materials for the hydrogen evolution reaction in a mildly alkaline buffer (0.1 M K₂CO₃/0.1 M KHCO₃), a medium chosen to prevent catalyst degradation. This work provides a crucial proof of concept for the application of cage-like metallasilsesquioxanes in HER electrocatalysis.