Nitrene Adducts with Oxygen in the Photooxidation Reactions of Organic Azides

The photooxidation of organic azides and the photochemical reduction of nitro compounds include the formation of a common intermediate: the adduct of a nitrene with oxygen. The ground state of the adduct is singlet; the singlet–triplet gap is small and equals 80.2 or 56.7 kJ/mol for HNOO or C₆H₅NOO, respectively. Arguments for the involvement of singlet molecular oxygen, atomic oxygen, hydroxyl radicals, and dioxaziridines in these reactions were given.