Reaction of a Nitrosyl Complex of Cobalt Porphyrin with Hydrogen Peroxide: Putative Formation of Peroxynitrite Intermediate.

The cobalt porphyrin complex [(Cl4 TPP)Co], 1, {Cl4 TPP = 5,10,15,20-tetrakis(4'-chlorophenyl)porphyrinate dianion} in dichloromethane solution was subjected to react with nitric oxide (NO) gas and resulted in the formation of the corresponding nitrosyl complex [(Cl4 TPP)Co(NO)], 2, having {CoNO}8 description. It was characterized by spectroscopic studies and single-crystal X-ray structure determination. It did not react with dioxygen. However, in CH2 Cl2 /CH3 CN solution, it reacted with H2 O2 to result in the Co-nitrito complex [(Cl4 TPP)Co(NO2 )], 3, with the simultaneous release of O2 . It induced ring nitration to the added phenol in an appreciable yield. The reaction presumably proceeds through the formation of corresponding Co-peroxynitrite intermediate.