A DFT study of the structure-property relationships of bistetrazole-based high-nitrogen energetic metal complexes

In this work, six series of new energetic metal complexes were designed. Each complex contained a large, high-energy, high-nitrogen, anionic chelating ligand (either the 5,5'-bistetrazolate anion, the 5,5'-azobistetrazolate anion, or the 5,5'-(hydrazine-1,2-diyl)bis-[1H-tetrazol-1-ide] anion-each of which has a different bridging group), Cu or Ni as the metal atom, and two small complexing agent ligands (NH₃ and/or NH₂NO₂). The molecular and electronic structures, heats of formation, densities, detonation properties, and impact sensitivities of the novel complexes were studied using density functional theory. Furthermore, the effects of varying the large chelating ligand (and thus the bridging group), the small complexing agents, and the metal atom on the structure and properties of the complex were investigated and analyzed in depth. The results show that the particular metal, bridging group, and complexing agents included in the energetic complex influence its structure and properties, but the effects of varying the constituents of the complex are complicated or unclear, and these effects are sometimes intertwined. In addition, the detonation pressures, detonation velocities, and impact sensitivities of the novel complexes ranged from 25.9 to 38.6 GPa, from 7.21 to 8.80 km s^-1, and from 17 to 48 cm, respectively. Five of the complexes (B3, C3, D3, E3, and F3) appear to possess comparable performance to the famous and widely used high explosive 1,3,5-trinitro-1,3,5-triazinane, making these new complexes attractive to energetic materials experimentalists.