Extensive theoretical studies on two new members of the FOX-7 family: 5-(dinitromethylene)-1,4-dinitramino-tetrazole and 1,1′-dinitro-4,4′-diamino-5,5′-bitetrazole as energetic compounds

Abstract

Two novel compounds 5-(dinitromethylene)-1,4-dinitramino-tetrazole (DNAT) and 1,1′-dinitro-4,4′-diamino-5,5′-bitetrazole (DNABT) were suggested to be potential candidates of high energy density materials (HEDMs). The optimized geometry, NBO charges and electronic density, HOMO–LUMO, electrostatic potential on the surface of molecules, the IR spectrum and thermochemical parameters were calculated for inspecting the electronic structure properties at B3LYP/6-311++G** level of theory. Meanwhile, the solid states of DNAT and DNABT were studied using the crystal packing models by the plane-wave periodic local-density approximation density functional theory. Four stable polymorphous cells have been found including P2₁2₁2₁, P2₁/c, P and Pbca, assigned to the orthorhombic, monoclinic and triclinic lattice systems. In addition, properties such as density, enthalpy of formation and detonation performance have also been predicted. As a result, the detonation velocity and pressure of two compounds are found to be very remarkable (DNAT: D = 9.17 km s⁻¹, P = 39.23 GPa; DNABT: D = 9.53 km s⁻¹, P = 40.92 GPa). Considering the tetrazole rings with energetic groups and the insensitive fragment of FOX-7, high positive heat of formation (583.50 kJ mol⁻¹ and 1081.39 kJ mol⁻¹) and eminent performance render DNAT and DNABT to be very promising powerful energetically insensitive compounds. This work provides theoretical support for further experimental synthesis.