Theoretical study on the pyrolysis of azobenzene and complex of azobenzene/NO2

The (U)MP2/6-311+G∗//(U)HF/6-31G∗ strategy was used to study the thermal decomposition mechanism of azobenzene and its complex with two NO2 radicals. The calculated results showed that the initial thermal decomposition of azobenzene mainly involved the homolytic fission of the CN bond. There existed an interaction between azobenzene and NO2. The geometry of the azobenzene in the complex changed significantly. Comparison of the activation energies indicated that the nitrobenzene and N2 should be the pyrolytic products of the complex. The bond dissociation energy of CNO2 bond for nitrobenzene was higher than that of NNO2, CNO2, and ONO2 bonds for some traditional nitro explosives. The pyrolysis characteristic of azobenzene in the NO2 environment can be used to modify the exothermic redox reaction pathways of NO2 radicals in the thermal decomposition of explosives and propellants.