Preparation, crystal structure, and thermal decomposition of the four-coordinated zinc compound based on 1,5-diaminotetrazole

The environmental friendly energetic coordination compound Zn(DAT) ₂(Ac)₂ (1) (Ac = acetic) was synthesized from 1,5-diaminotetrazole (DAT), and characterized by elemental analysis and FT-IR spectroscopy. The crystal structure was determined by X-ray single crystal diffraction. The crystallographic data showed that compound 1 belongs to the monoclinic system, space group Cc, with cell parameters: a = 17.595(5) Å, b = 7.3060(18) Å, c = 14.076(4) Å, β = 123.449(4)°, V = 1509.7(7) ų, Z = 4, D_c = 1.688 g·cm ^-3. In 1, the zinc cation is four-coordinated with two oxygen atoms from the two acetic carboxyl groups and two 4-nitrogen atoms of DAT molecules, and exhibits a distorted-tetrahedron configuration. Thermal decomposition mechanism was determined based on differential scanning calorimeter (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) analysis. Kinetic parameters of the first exothermic process were studied by using Kissinger's method and Ozawa's method, respectively. The critical temperature of thermal explosion, entropy of activation (ΔS^≠), enthalpy of activation (ΔH^≠), and free energy of activation (ΔG^≠) were calculated and obtained as 519.71 K, -144.04 J·(K·mol)^-1, 152.20 kJ·mol^-1 and 224.99 kJ·mol^-1, respectively. The constant-volume energy of combustion (9.78 MJ·kg^-1) was measured by oxygen bomb calorimetry, which was equal to that of RDX. In the end, the sensitivities properties were also determined with standard method.