Conversion of Carbon Dioxide to Oxalate by α‑Ketocarboxylatocopper(II) Complexes

The α-ketocarboxylatocopper­(II) complex [{Cu­(L1)}­{O2CC­(O)­CH­(CH3)2}] can be spontaneously converted into the binuclear oxalatocopper­(II) complex [{Cu­(L1)}2(μ-C2O4)] upon exposure to O2/CO2 gas. 13C-labeling experiments revealed that oxalate ions partially incorporated 13CO2 molecules. Furthermore, the bicarbonatocopper­(I) complex (NEt4)­[Cu­(L1)­{O2C­(OH)}] in an Ar atmosphere and the α-ketocarboxylatocopper­(I) complex Na­[Cu­(L1)­{O2CC­(O)­CH­(CH3)2}] in an O2 atmosphere were also transformed spontaneously into the oxalato complex [{Cu­(L1)}2(μ-C2O4)].