Synthesis, structure, and thermal decomposition of two copper coordination compounds [Cu(DAT)₂(PA)₂] and [Cu(DAT)₂(HTNR)₂] with nitrogen rich 1,5-diaminotetrazole (DAT)

Both [Cu(DAT)₂(PA)₂] (1) and [Cu(DAT)₂(HTNR)₂] (2) were prepared from 1,5-diaminotetrazole (DAT) and copper trinitrophenol, 1 for picrate (PA) and 2 for styphnate acid (2,4,6-trinitro resorcinol, TNR), and were characterized by elemental analysis, FT-IR spectroscopy, and single crystal X-ray diffraction. The space group of these compounds is P₂₁/c (monoclinic). The lattice parameters are similar [a = 11.405(3) Å, b = 14.867(3) Å, c = 8.099(2) Å for 1 and a = 12.262(3) Å, b = 14.900(3) Å, c = 7.243(2) Å for 2], except the β = 106.257(3)° in 1 and β = 92.989(4)° in 2. Both have extended structures due to hydrogen bonds, but there are some differences because of the ligands induced effect. Differential scanning calorimetry analysis shows that two exothermic processes take place in both complexes, the first peak temperatures are 488.2 K for 1 and 519.2 K for 2. The kinetic parameters of the first exothermic process were studied by using Kissingers method and Ozawas method, in which the enthalpy of formation (-7346 and -5706 kJ M^-1), critical temperature of thermal explosion (475.0 and 515.8 K), entropy of activation (ΔS^≠), enthalpy of activation (ΔH^≠), and free energy of activation (ΔG^≠) were calculated and obtained as -117.25 J K^-1 M^-1, 140.64 kJ M^-1, 196.44 kJ M^-1 and -219.1 J K^-1 M^-1, 383.56 kJ M^-1, 495.34 kJ M^-1 for 1 and 2, respectively. The sensitivity test results showed that both compounds were sensitive to impact (<5 J) and flame (>20 cm) rather than friction.