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(NO 2 ) 2 , and a calculated heat of formation (0 K) 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(NO 2 )(NOOH) is ΔH 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(NO 2 ) 2 radical to be 5.0±0.5 eV and the N-N bond dissociation energy of HN(NO 2 ) 2 to be 48± 8 kcal/mol