Mechanistic Insight into the Nitric Oxide Dioxygenation Reaction of Nonheme Iron(III)–Superoxo and Manganese(IV)–Peroxo Complexes

Abstract

AbstractReactions of nonheme FeIII–superoxo and MnIV–peroxo complexes bearing a common tetraamido macrocyclic ligand (TAML), namely [(TAML)FeIII(O2)]2− and [(TAML)MnIV(O2)]2−, with nitric oxide (NO) afford the FeIII–NO3 complex [(TAML)FeIII(NO3)]2− and the MnV–oxo complex [(TAML)MnV(O)]− plus NO2−, respectively. Mechanistic studies, including density functional theory (DFT) calculations, reveal that MIII–peroxynitrite (M=Fe and Mn) species, generated in the reactions of [(TAML)FeIII(O2)]2− and [(TAML)MnIV(O2)]2− with NO, are converted into MIV(O) and .NO2 species through O−O bond homolysis of the peroxynitrite ligand. Then, a rebound of FeIV(O) with .NO2 affords [(TAML)FeIII(NO3)]2−, whereas electron transfer from MnIV(O) to .NO2 yields [(TAML)MnV(O)]− plus NO2−.