Theoretical study on the thermal decomposition mechanism of 3,3′-dinitro-4,4′-azoxyfurazan

The molecular structure and thermal decomposition of 3,3′-dinitro-4,4′-azoxyfurazan (DNOAF) were studied at the B3LYP/6-311++G** level of theory. The geometry optimization showed that trans-DNAOF has a twisting configuration due to the substituted NO2 on the furazan rings and the oxidation of azo-group. The bond dissociation energies of the two C-N bonds which connect the furazan rings and azo-group were found to be 65.9 and 92 kcal/mol, respectively, suggesting that the C-N bond on the side of O-atom of azoxy-group is relatively weak. For the initial decomposition product B1, the activation energy of N2O elimination was calculated to be up to 88.1 kcal/mol. The O1-N5 bond dissociation is a very energetically favorable pathway for the ring-opening reaction of the intermediate B2 because the activation energy was found to be only 0.3 kcal/mol. The following reaction of B2 included the rearrangement of NO2 to ONO followed by the direct loss of NO group. The whole reaction process of B2 was exothermic.