Nitric oxide redox-related reactions

Bimolecular reactions of the ion-radical pair can also effectively compete with the back electron transfer if either component undergoes a rapid reaction with an additive that is present during the ET activation. In NO+/arene systems, the introduction of oxygen rapidly oxidizes even small amounts of nitric oxide to compete with back ET and thus successfully effect aromatic nitration [60]. In a related example, the CT complex of hexamethylbenzene and maleic anhydride reaches a photostationary state with no productive reaction. However, if irradiation is carried out in the presence of an acid, the anion radical in the resulting contact ion-radical pair is readily protonated, and the redox equilibrium is driven toward coupling (in competition with the back ET) to yield the photoadduct [59], i.e. ... 

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