ON THE STRUCTURE AND THERMOCHEMISTRY OF HYDROGEN DINITRAMIDE

Five stable conformations of hydrogen dinitramide have been identified through ab initio electronic structure calculations. The most stable form has a secondary amine structure, HN(NO2)2, and a calculated heat of formation (OK) of 28.4 kcal/mol. Four stable inorganic acid structures are found to lie 7.9-9.7 kcal/mol higher in energy. The predicted enthalpy of deprotonization of N(NO2)(NOOH) is DELTAH(acid)(298 K) = 302.6 +/- 2 kcal/mol, making this one of the strongest known gas-phase inorganic acids. We estimate the electron affinity of the N(NO2)2 radical to be 5.0 +/- 0.5 eV and the N-N bond dissociation energy of HN(NO2)2 to be 48 +/- 8 kcal/mol. It is shown that unimolecular decomposition is the most likely low-energy decomposition mechanism for hydrogen dinitramide.