Cobaltmeso-Tetrakis(N-methyl-4-pyridiniumyl)porphyrin Becomes a Catalyst for the Electroreduction of O2by Four Electrons When [(NH3)5Os]n+(n= 2, 3) Groups Are Coordinated to the Porphyrin Ring

Abstract

The reaction between the water-soluble cobalt porphyrin 1 and [(NH3)5Os(OH2)]2+ produces a multiply-osmiumated product that spontaneously adsorbs on graphite electrodes and acts as a catalyst for the reduction of O2 by four electrons. The nonosmiumated cobalt porphyrin is also adsorbed but catalyzes only the two-electron reduction of O2.