Theoretical studies on the thermodynamic properties, densities, detonation properties, and pyrolysis mechanisms of trinitromethyl-substituted aminotetrazole compounds

Theoretical investigation on the structure and performance of N, N'-azobis-polynitrodiazoles

Six novel high energy density compounds of N, N'-azobis-polynitrodiazoles were designed. Their optimized geometric and electronic structures, band gaps, and heats of formation were explored at B3LYP/aug-cc-pVDZ level of density functional theory (DFT). Detonation properties were predicted by Kamlet-Jacobs equations. Results show that the designed compounds have high densities (1.80 to 1.84 g · cm⁻³) and excellent detonation performance (D 8.51 to 9.02 km · s⁻¹, P 32.16 to 36.58 GPa). In addition, the bond dissociation energies of C-NO₂ bonds were found to range from 223.59 to 240.46 kJ · mol⁻¹. All of them appear to be potential explosives compared with the well known ones, 1,3,5-trinitro-1,3,5-triazine (RDX, 8.75 km · s⁻¹, 34.70 GPa) and octahydro- 1,3,5,7-tetranitro-1,3,5,7-tetraazocane (HMX, 8.96 km · s⁻¹, 35.96 GPa), especially R3 (8.98 km · s⁻¹, 36.19 GPa) and R6 (9.02 km · s⁻¹, 36.58 GPa). Finally, the position and number of nitro groups in the N, N'-azobis-polynitrodiazoles determine the heat of formation, stability, sensitivity, density, and detonation performance of these compounds.

Theoretical investigations on heat of formation, detonation performance, and pyrolysis mechanism of 1,3,5,7,9,11-hexo(nitramine)-2,4,6,8,10,12- hexaazatetracyclo[5,5,0,0,0]dodecane

The B3LYP/6-311G(d,p) method was used to investigate IR and Raman spectra, heat of formation, and thermodynamic properties of a newly designed polynitro cage compound 1,3,5,7,9,11-hexo(nitramine)-2,4,6,8,10,12-hexaazatetracyclo[5,5,0,0,0]dodecane. The detonation and pressure were evaluated by using the Kamlet−Jacobs equations based on the theoretical density and condensed heat of formation. The bond dissociation energies and bond orders for the weakest bonds were analyzed to investigate the thermal stability of the title compound. The results show that the N9−NO2 bond is predicted to be the trigger bond during pyrolysis. There exists an essentially linear relationship between the Wiberg bond indices of N−NO2 bonds and the charges –QNO2 on the nitro groups. The crystal structure obtained by molecular mechanics belongs to the P21 space group, with lattice parameters Z = 2, a = 10.9220 Å, b = 13.6669 Å, c = 9.4659 Å, and ρ = 2.05 g cm−3.