Electrochemical reduction of CO2 by binuclear Co and Ni complexes

Several bis(metal) complexes of biscyclam 2 (Me=Co,Ni) were prepared by Fabbrizzi’s method and they were electrochemically characterised, using a rotating ring-disk electrode. It was confirmed that these complexes have no special advantage for the electrocatalytic reduction of C02. A second class of binuclear metal complexes was prepared, using 2,5-diformylfuran as a starting inaterial. They were found to decompose af the electrode. Thereupon the research was continued with the mononuclear tetraazamacrocyclic complexes of Co and Ni, as used before, nou in completely dry solvent. The complexes were found to be stable at the electrode only when traces of water were present. Finally, some Rh and Ir complexes with (substituted) diphos ligands were prepared and characterised, following a report on Rh(diphos)2 by Slater et al. The electron-withdraving substituent -CF3 was found to lower the reduction potential for C02