Computational investigation of the properties of double furazan-based and furoxan-based energetic materials.

As a kind of promising energetic materials, the double furazan-based and furoxan-based compounds have raised concerns of many researchers in recent years. In this paper, the optimized structures, energetic properties, heat of formation (HOF), detonation properties, and bond dissociation energies of these compounds were calculated by density functional theory (DFT) method. The results show that the N-O bond, which is close to the adjacent coordinated oxygen atom in furoxan ring, is more fragile than the other N-O bonds in the ring. The double furazan-based derivatives are more stable than the double furoxan-based derivatives. All the titled compounds are divided into five groups because of the different substitute groups on both ends. The HOFs of the substances offer the order of 4 group (the both ends are 1,2,3,4-tetrazine ) ≈ 5 group (1,2,4,5-tetrazine) > 3 group (tetrazole) ≈ 1 group (1,2,3-triazole) > 2 group (1,2,4-triazole). All the title compounds also can be divided into three types with the different linkages, -N=N-, -N=N(O)-, and -NH-NH-. The results show that the HOFs of the compounds with different linkages obey the order -N=N- type > -N=N(O)- type> -NH-NH- type. For all titled compounds, bis(4-(1,2,4,5-tetrazin-3-yl)-1,2,5-oxadiazol-3-yl) diazene (E5) has the best gas-phase and solid-phase HOFs. The heat of detonation(Q) of bis(3-(1,2,3,4-tetrazin-5-yl)-1,2,5-oxidiazole-2 -oxide)diazene-1,2-diyl (B4) is the best of all titled compounds. The density of bis((3-2H-tetrazol-5-yl)-1,2,5-oxidiazole -2-oxide)oxidodiazene-1,2-diyl (A3) is the best and the second best is bis((4-2H-tetrazol-5-yl)-1,2,5-oxidiazol-3-yl) diazene (E3). The detonation velocities and detonation pressure of A3 and E3 are better than other titled compounds. 1,2-bis((4-2H-tetrazol-5-yl)-1,2,5 -oxidiazol-3-yl) diazene-1-oxide (D3) and 1,2-bis((4-2H-tetrazol-5-yl)-1,2,5-oxidiazol-3-yl) hydrazine (F3) have superior D and P with low sensitivity. The tetrazole ring plays a vital role in improving detonation velocities and pressure. The results can provide some foundational information for designing new high-density energetic materials.