[5,10,15,20-Tetrakis(4-((pentaammineruthenio)- cyano)phenyl)porphyrinato]cobalt(II) Immobilized on Graphite Electrodes Catalyzes the Electroreduction of O₂ to H₂O, but the Corresponding 4-Cyano-2,6-dimethylphenyl Derivative Catalyzes the Reduction Only to H₂O₂

Abstract

Cobalt porphyrins in which Ru(NH3)52+ groups are coordinated to four cyanophenyl ligands pendant to the porphyrin ring act as catalysts for the electroreduction of O2 when adsorbed on the surface of graphite electrodes. The parent 4-cyanophenyl derivative catalyzes the four-electron reduction of O2 to H2O, but the 4-cyano-2,6-dimethylphenyl derivative catalyzes only the two-electron reduction of O2 to H2O2.