Calculation of the properties of molecules in the pyridine catalyst system for the photochemical conversion of CO2 to methanol

► C5NH5COO− and C5NH5COOH form stable complexes in solution. ► The C5NH5CO2 complex is much easier to reduce than free CO2. ► The complex anion absorbs in the UV-visible. ► Some of its excited states show breakage of the N-C bond and formation of the COO− radical.