Theoretical evaluation of hexazinane as a basic component of nitrogen-rich energetic onium salts

Abstract

In the present paper, we report a comprehensive theoretical evaluation of a hypothetical compound, hexazinane (cyclo-H₆N₆), and its 10 onium salts as high-energy density materials. Crystal structure prediction, which included dynamical and mechanical stability criteria estimation, found a P2₁/c space group crystal structure to be the lowest energy polymorph. Prediction of the chemical reactivity parameters of a hexazinane molecule revealed a strong basic character comparable with those of secondary and tertiary aliphatic amines. The onium salts of hexazinane with the carbon-free inorganic anions (N_xO_y)⁻ and with several low carbon content organic anions demonstrate excellent detonation characteristics. Hexazinanium nitrate H₇N₆⁺NO₃⁻ has detonation performance comparable with ε-CL-20, the most powerful non-nuclear explosive known. The corresponding salts with dinitramide N(NO₂)₂⁻ and nitrite NO₂⁻ anions have only slightly lower characteristics more powerful than all known explosives, except for ε-CL-20 and octanitrocubane. The reported “green” energetic materials also demonstrate excellent propulsive performance, and, if synthesized, these may find potential applications as solid rocket propellants.