A Novel Mechanism for Nitric Oxide Production in Nitroalkyl Radicals that Circumvents Nitro−Nitrite Isomerization

ABSTRACT: In this study, we present a novel mechanism for NO loss from nitroalkyl radicals that circumvents the traditional higher-energy nitro−nitrite isomerization. We characterize the intrinsic reaction coordinate at the B3LYP/6-311++g(3df,2p) level of theory and calculate the transition-state energies using the G4 composite method; the subsequent dynamics en route to the highly exothermic NO + acetone product channel proceeds through a three-membered ring intermediate. Crossed laser-molecular beam scattering experiments on the 2-nitro-2-propyl radical confirm the importance of this new mechanism in determining the product branching. SECTION: Molecular Structure, Quantum Chemistry, and General Theory The decomposition mechanisms of nitroalkanes have beenstudied experimentally and theoretically for decades because of their relevance to a wide variety of chemistry ranging from atmospheric mechanisms to energetic materials. Nitroalkanes can undergo numerous dissociation events, but two of the most studied are NO2 loss and NO loss. Loss of NO2 tends to arise from simple C−N bond fission, but th