Preparation, crystal structure, and thermal decomposition of an azide energetic compound [Cd(IMI)2(N3)2]n (IMI = imidazole)

Abstract

Cadmium(II) imidazole (IMI) azide [Cd(IMI)2(N3)2]n (1) was synthesized using imidazole and azide, and was characterized by the elemental analysis and FTIR spectrum. The crystal structure was determined by X-ray single crystal diffraction, and the crystallographic data show that the crystal belongs to orthorhombic, Pba2 space group, α = 10.780(4) Å, b = 13.529(5) Å, and c = 3.6415(12) Å. Its crystal density is 2.080 g·cm–3. Cd(II) is a six-coordinate with six nitrogens from four imidazoles and two azides with μ–1,1 coordination. The thermal decomposition mechanism was determined based on differential scanning calorimetry (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) analysis, and the kinetic parameters of the first exothermic process were studied using Kissinger’s method and Ozawa’s method, respectively. The energy of combustion, enthalpy of formation, critical temperature of thermal explosion, entropy of activation (ΔS ≠), enthalpy of activation (ΔH ≠), and free energy of activation (ΔG ≠) were measured and calculated. In the end, impact sensitivity was also determined by standard method.