Density functional theory studies on two novel poly-nitrogen compounds: N(5)(+)N(3)(-)and N5+N5-

摘要

Density functional theory (DFT) methods with B3LYP/6-311++g(d,p) level of theory were employed to study two poly-nitrogen salts N(5)(+)N(3)(-)and N5+N5-. The optimized geometries and thermochemical parameters, frontier molecular orbitals, molecular electrostatic potential, and predicted infrared (IR) spectra were calculated for inspecting the molecular stabilities, electronic structures, and chemical reactivity. The energetic properties including densities, solid state heats of formation, heats of detonation, detonation velocities, and detonation pressures of N(5)(+)N(3)(-)and N(5)(+)N(5)(-)were also calculated. Results show that the planar N(5)(+)N(3)(-)and N(5)(+)N(5)(-)have higher heats of formation (>1000 kJ mol(-1)) than that of HMX (116.1 kJ mol(-1)) and CL-20 (365.4 kJ mol(-1)). The detonation velocity of N(5)(+)N(3)(-)is 9.29 km s(-1), which is comparable with HMX (9.22 km s(-1)). Especially, N(5)(+)N(5)(-)has a higher detonation velocity (10.21 km s(-1)) than HMX and CL-20, which means it could be an excellent high-energy-density material (HEDM). However, they have a very small energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), which predicts that they have poor stabilities.