Cn. Shi et Fc. Anson, (5,10,15,20-TETRAMETHYLPORPHYRINATO)COBALT(II) - A REMARKABLY ACTIVE CATALYST FOR THE ELECTROREDUCTION OF O-2 TO H2O, Inorganic chemistry, 37(5), 1998, pp. 1037-1043
Unlike most simple, monomeric cobalt porphyrins, the cobalt tetramethy
lporphyrin identified in the title catalyzes the electroreduction of O
-2 to H2O instead of H2O2. On graphite electrodes, coatings of the por
phyrin prepared by irreversible adsorption from chloroform solutions c
atalyze the electroreduction of O-2 in aqueous HClO4 at unusually posi
tive potentials. Both the title porphyrin and the corresponding unsubs
tituted cobalt porphine are argued to derive their activity as four-el
ectron reduction catalysts from their propensity to form dimers (or hi
gher aggregates) in solution and, presumptively, on the surface of gra
phite electrodes.