Photochemistry of 1-(N,N-diethylamino)diazen-1-ium-1,2-diolate: an experimental and computational investigation.

The aqueous photochemistry of the sodium salt of 1-(N,N-diethylamino)-diazen-1-ium-1,2-diolate (3) has been investigated by both experimental and computational methods. Photolysis results in the formation of the N-nitrosodiethylamine radical anion (5) and nitric oxide (NO) via a triplet excited state. The nitrosamine radical anion either undergoes electron transfer with NO before cage escape to form triplet NO(-) and nitrosamine (minor process) or rapidly dissociates to form an additional molecule of NO and ultimately amine (major process). The production of nitrosamine radical anion 5 upon photolysis of diazeniumdiolate 3 is confirmed by low-temperature EPR spectroscopy. The calculated energetics for the ground and excited states of the parent diazeniumdiolate ion at the CIS and B3LYP levels of theory as well as B3LYP calculations on the fragmentation processes were very effective in rationalizing the observed photodissociation processes.