ELECTROCATALYTIC REDUCTION OF CO2 INTO FORMATE WITH [(ETA(5)-ME5C5)M(L)CL](-BIPYRIDINE LIGANDS - M = RH(III) AND IR(III))() COMPLEXES (L = 2,2')

The ability of [(eta(5)-Me5C5)M(L)Cl](+) (L = 2,2'-bipyridine ligands; M = Rh(III) and Lr(III)) to act as an electrocatalyst for CO, reducti on has been examined in an aqueous organic medium. It appears that the Rh(III) complex is a better catalyst than the Ir(III) one, and that a current efficiency for formate production of up to 50% can be reached . The initial step of the electrocatalysis involves the formation of t he corresponding hydride complex. Immobilization of such catalysts on the electrode surface, by the technique of functionalized polypyrrole films, decreases their efficiency as a consequence of the lower effici ency of the insertion of CO2 into the metal-hydride bond. (C) 1997 Els evier Science S.A.