Exploring the nitric oxide dioxygenation (NOD) reactions of manganese–peroxo complexes

Abstract

Here, we report the nitric oxide dioxygenation (NOD) reactions of two Mn^III–peroxo (M^III–O₂²⁻) complexes, [(3PYENMe)Mn^III(O₂²⁻)]⁺ (1) and [(N3PY)Mn^III(O₂²⁻)]⁺ (2), bearing pentadentate ligands. Complexes 1 and 2 give Mn^II–nitrate (Mn^II–NO₃⁻) complexes (3 and 4) when reacted with nitric oxide (NO), respectively. The mechanistic study explored by using 2,4-di-tert-butylphenol (2,4-DTBP) suggested that the NOD reaction of 1 and 2 occurs via a presumed Mn–peroxynitrite ([Mn–PN]⁺, [Mn–ONOO⁻]⁺) intermediate. Tracking the source of N atoms using ¹⁵NO revealed that the N-atoms in Mn^II–NO₃⁻ (3 and 4) are derived from the ¹⁵NO moiety. Furthermore, we have explored the M^III–O₂²⁻ regeneration from NOD products (3 and 4), and we have observed the formation of M^III–O₂²⁻ complexes (1 and 2) upon treatment with KO₂ or H₂O₂/triethylamine (TEA), respectively.