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

Reactions of nonheme Fe III –superoxo and Mn IV –peroxo complexes bearing a common tetraamido macrocyclic ligand (TAML), namely [(TAML)Fe III (O 2 )] 2− and [(TAML)Mn IV (O 2 )] 2− , with nitric oxide (NO) afford the Fe III –NO 3 complex [(TAML)Fe III (NO 3 )] 2− and the Mn V –oxo complex [(TAML)Mn V (O)] − plus NO 2 − , respectively. Mechanistic studies, including density functional theory (DFT) calculations, reveal that M III –peroxynitrite (M=Fe and Mn) species, generated in the reactions of [(TAML)Fe III (O 2 )] 2− and [(TAML)Mn IV (O 2 )] 2− with NO, are converted into M IV (O) and . NO 2 species through O−O bond homolysis of the peroxynitrite ligand. Then, a rebound of Fe IV (O) with . NO 2 affords [(TAML)Fe III (NO 3 )] 2− , whereas electron transfer from Mn IV (O) to . NO 2 yields [(TAML)Mn V (O)] − plus NO 2 − .