Dinitraminic acid (HDN) isomerization and self-decomposition revisited

Density functional theory (DFT) and the ab initio based CBS-QB3 method have been used to study possible decomposition pathways of dinitraminic acid HN(NO2)2 (HDN) in gas-phase. The proton transfer isomer of HDN, O2NNN(O)OH, and its conformers can be formed and converted into each other through intra- and intermolecular proton transfer. The latter has been shown to proceed substantially faster via double proton transfer. The main mechanism for HDN decomposition is found to be initiated by a dissociation reaction, splitting of nitrogen dioxide from either HDN or the HDN isomer. This reaction has an activation enthalpy of 36.5 kcal/mol at the CBS-QB3 level, which is in good agreement with experimental estimates of the decomposition barrier.