Dft theoretical study on nitrogen-rich compounds C₆H_6-n (N₃)_n (n = 1-6)

The heats of formation (HOFs) were calculated for nitrogen-rich compounds C₆H_6-n (N₃)_n (n = 1-6), via density functional theory (DFT) with 6-31G* basis set. We chose be nzene and HN3 as reference compounds in the process of designing isodesmic reactions. The relationship between the HOFs and the molecular structures is discussed. The results show that the HOFs of the title compounds linearly increase with increasing number of azide groups. The relative stabilities of the title compounds are discussed in terms of Mulliken charge, bond order, and the energy gaps between the frontier orbitals. All of the geometries of the title compounds were fully optimized without applying symmetry or structural constraints. This was accomplished via the default Gaussian convergence criteria. All of the optimized structures were characterized as true local energy minima on the potential energy surfaces, without imaginary frequencies.