Preparation, crystal structure and thermal analyses of 1,5-diamino-4-hydro- 1,2,3,4-tetrazolium 3,5-dihydroxy-2,4,6-trinitrophenolate

A novel energetic salt 1,5-diamino-4-hydro-1,2,3,4-tetrazolium 3,5-dihydroxy-2,4,6-trinitrophenolate was synthesized by the reaction of 1,5-diamino-1,2,3,4-tetrazole (DAT) with 2,4,6-trinitro-1,3,5-trihydroxybenzene (trinitrophloroglucinol, TNPG). It was characterized by X-ray single crystal diffraction, elemental analysis, FT-IR spectroscopy and ¹H NMR. The title compound crystallizes in monoclinic system, P2(1)/c space group with crystal parameters of a=1.3399(3) nm, b=0.47088(9) nm, c=2.0127(4) nm, β=92.83(3)°, V=1.2684(4) nm³, Z=4. Hydrogen bonds, electrostatic interactions, and weak van der Waals' forces make the molecules form a stable three-dimensional net structure. Mulliken charge distribution and overlap population of DAT and DATH⁺TNPG^- in bulk state have been obtained from the density functional theory (DFT) with the B3LYP method employing the 6-31G** basis sets to interpret the reason why the protonation site of DAT is N(4) atom of the tetrazole ring. Thermal decomposition of the title compound was studied by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) techniques. The high enthalpy change and leaving no solid residue after thermal decomposition indicate that the title compound can be used as a promising energetic material or gas-generating composition. The kinetic parameters of the exothermic process of DATH⁺TNPG^- were studied by using Kissinger's and Ozawa-Doyle's methods and the Arrhenius equation of this process was obtained.