Reaction of a Nitrosyl Complex of Co(II)‐Porphyrin with Hydrogen Peroxide: Formation of a Porphyrin Radical Cation

Abstract

A nitrosyl complex of Co(II)‐porphyrinate, [CoII(TTMPP2‐)(NO)], 1, [TTMPPH2 = 5,10,15,20‐tetrakis(3,4,5‐trimethoxyphenyl)porphyrin] having {Co(NO)}8 configuration has been synthesized and characterized spectroscopically as well as structurally. Complex 1 in dichloromethane:acetonitrile (1:4, v/v) solution at ˗40 °C reacts with hydrogen peroxide (H2O2) to result in the corresponding nitrite (NO2‐) complex, [CoIII(TTMPP2‐)(NO2‐)], 2. The formation of a Co(III)‐peroxynitrite intermediate is presumed in this reaction based on the characteristic phenol ring nitration test. From spectroscopic studies, formation of [CoIV=O] species followed by a Co(III)‐porphyrin radical complex was observed during the course of the reaction.