Theoretical investigation of a series of bis(1H-tetrazol-5-yl)furazan and bis(1H-tetrazol) derivatives as high-energy-density materials

Using density functional theory (DFT), a series of bis(1H-tetrazol-5-yl)furazan and bis(1H-tetrazol) derivatives with different linkages and substituents are investigated theoretically as potential high-energy-density materials (HEDMs). The heat of formation (HOF), detonation properties, natural bond orbital (NBO) and thermal stabilities are calculated and reported. The introduction of a furazan ring, an –N=N– bridge group and an –N₃ substituent is beneficial to increase the HOF of the title compounds. NBO analysis shows that there are electronic delocalisation effects among the bridge groups, furazan and tetrazole rings, and substituted groups. The conjugation effects and electronic transitions are influenced by the different linkages and substituents. The estimated detonation velocities and pressures indicate that the –ONO₂ and –NO₂ groups and the –N=N– linkage play important roles in enhancing the detonation properties. The bond dissociation energy (BDE) calculations reveal that the –NO₂ group is the substituent group which causes the least thermal stability. The bond between the substituent group and the tetrazole ring is the weakest bond in the title molecules. Considering the detonation performance and the thermal stability, 17 compounds may be promising candidates for HEDMs with good performance. Eight of them (A3, A4, C3, C4, D3, F3, G1 and G3) have better detonation properties than HMX.