Theoretical kinetic study on the decomposition of 1,5-diaminotetrazole

1,5-Daminotetrazole (DAT) is of much interest because of the practical significance and the diversity of characteristics. The study on the decomposition pathway and the kinetics of DAT has been performed based on the quantum chemistry theory. The minimum energy path (MEP) calculation has shown that NH₂N₃ and NH₂CN are the initially detected products of DAT. And the structures of reactant, products and transition state were optimized with MP2 methods using 6-311G∗∗ basis sets, and the energies were refined using CCSD(T)/6-311G∗∗ levels of theory. The calculated rate constants were obtained using the conventional transition-state theory (TST) and the canonical variational transition-state theory (CVT) methods. The calculation results indicated that the energy barrier of decomposition reaction is 47.98 kcal mol^-1 and the variational effect is small. In addition, the rate constants and the Arrhenius experience formula of DAT decomposition have been obtained between 200 and 2500 K temperature regions. The fitted three-parameter expressions calculated using the TST and CVT methods are k(T)=1.27×10^-26×T^3.60×e(^-8.07×103/T)s^-1 (TST) and k(T)=9.78×10¹¹×T^0.88×e(^-2.51×104/T)s^-1 (CVT). This work may provide the theoretical support for further experimental synthesis and testing.