Dimerization and trapping of diazirinyl radicals

Abstract

Computational and experimental methods have been utilized to examine the facile dimerization of diazirinyl radicals. Two potential dimers were investigated using density functional theory. Both were shown to have low-barrier reaction coordinates leading to formation of HCN and N₂. A cross-over experiment was employed to establish the relative contributions of C–N and N–N dimers towards product formation. The N–N dimerization was found to be dominant under the current conditions, and the corresponding reaction coordinate energetics were further explored using coupled-cluster methods. A detailed mechanism for dimer decomposition is presented. The competition between unimolecular and bimolecular reactions of diazirinyl radicals is explored under high dilution conditions. The high reactivity of the diazirinyl radical as a nitrogen atom transfer agent suggests a possible bimolecular contribution for “prompt” NO formation in hydrocarbon combustion with diazirinyl radicals as intermediates.