Copper(ii) defect-cubane water oxidation electrocatalysts: from molecular tetramers to oxidic nanostructures

We report on the synthesis and spectroscopic evidence for a sequence of structural transformations of a new defect-cubane type copper complex, [Cu(4)(pyalk)(4)(OAc)(4)](ClO(4))(HNEt(3)), which acts as a pre-catalyst for water oxidation. In situ and post-catalytic studies showed that the tetrameric complex undergoes a structural transformation into dimeric and monomeric species, induced by water molecules and carbonate anions, respectively. Further, the observed electrocatalytic water oxidation activity has been confirmed to arise from in situ-generated Cu(ii) oxidic nanostructures at the electrode interface.