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

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 chemical reactivity parameters of a hexazinane molecule revealed a strong basic character comparable with secondary and tertiary aliphatic amines. The onium salts of hexazinane with the carbon-free inorganic anions (NxOy)– and with several low carbon content organic anions demonstrate excellent detonation characteristics. Hexazinanium nitrate H7N6+NO3– has detonation performance being comparable with e-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 being more powerful than all known explosives, except of e-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.