Densities, Heats of Formation, Energetic Properties, and Thermodynamics of Formation of Energetic Nitrogen-Rich Salts Containing Substituted Protonated and Methylated Tetrazole Cations: A Computational Study

We have performed density functional theory and volume-based thermodynamics calculations to study the effects of different substituents and energetic anions on the densities, heats of formation, energetic properties, and thermodynamics of formation for a series of energetic nitrogen-rich salts composed of the substituted protonated and methylated tetrazole cations with nitrate, dinitroamide, azide, and perchlorate anions. The volumes of the cations and anions were estimated to get the crystal densities of the salts from electronic structure calculations. The heats of formation (HOFs) of cations, anions, and lattice energies of the salts were calculated separately to obtain the HOFs of the salts based on Born−Haber energy cycles. According to the densities and HOFs, the detonation velocities and detonation pressures of the salts were predicted by the Kamlet−Jacobs equations. Finally, the lattice enthalpies and entropies were used to construct a thermodynamic cycle for salt formation to predict the possibility to synthesize the salts. This procedure provides a straightforward and inexpensive route to screen a large number of potential energetic ionic salts.