DFT studies on a high-energy density cage compound 1, 3, 5, 7, 9, 11-hexo(N(CH₃)NO₂)-2, 4, 6, 8, 10, 12-hexaazatetracyclo[5, 5, 0, 0, 0] dodecane

Abstract

The infrared and Raman spectra, heat of formation (HOF) and thermodynamic properties were investigated by B3LYP/6-31G^** method for a new designed polynitro cage compound 1,3,5,7,9,11-hexo(N(CH₃)NO₂)-2,4,6,8,10,12-hexaazatetracyclo[5,5,0,0,0]dodecane. The detonation velocity (D) and pressure (P) were predicted by the Kamlet–Jacobs equations based on the theoretical density and condensed HOF. The bond dissociation energies and bond orders for the weakest bonds were analysed to investigate the thermal stability of the title compound. The computational result shows that the detonation velocity and pressure of the title compound are superior to those of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), but inferior to those of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) and hexanitrohexaazaisowurtzitane (HNIW). And the analysis of thermal stability shows that the first step of pyrolysis is the rupture of the N₇–NO₂ bond. The crystal structure obtained by molecular mechanics belongs to the P2₁ space group, with the lattice parameters Z = 2, a = 11.8246 Å, b = 10.4632 Å, c = 15.9713 Å, ρ = 1.98 g cm⁻³.

Keywords:

• density functional theory
• heat of formation
• detonation properties
• bond dissociation energy
• thermodynamic properties

Acknowledgements

We gratefully thank the Jiangsu Planned Projects for Postdoctoral Research Funds (No. 1201015B) and China Postdoctoral Science Foundation (No. 2013M531361) for their support of this work.