Theoretical design of novel high energy metal complexes based on two complementary oxygen-rich mixed ligands of 4-amino-4H-1,2,4-triazole-3,5-diol and 1,1'-dinitramino-5,5'-bistetrazole.

In this study, 16 new energetic metal complexes [M(DNABT)(ATDO), M=Cu, Ni] were designed using the mixed complex construct strategy, which was based on two complementary oxygen-rich high-energy ligands of 1,1'-dinitramino-5,5'-bistetrazole (DNABT) and 4-amino-4H-1,2,4-triazole-3,5-diol (ATDO), then combined with metals Cu and Ni, and further adjusted by the introduction of NO2 and NH2. The molecular and electronic structures, heat of formation (HOF), density, detonation velocity, detonation pressure, and sensitivity were investigated by the density functional theory method. The results showed that in metals, the position and amount of NO2/NH2 have great effects on the structure and property of metal complexes, and these effects coupled with each other. N-NO2 bond is the relatively weak bond, and its max length is related with the sensitivity closely. The designed metal complexes all have high HOF (673~868 kJ mol-1), high density (2.06~2.14 g cm-3), and ideal oxygen balance (- 19.2~- 6.7%), which further make them have higher detonation velocity (8.76~9.84 km s-1) and detonation pressure (37.4~46.6 GPa) than three famous high-energy compounds 1,3,5-trinitro-1,3,5-triazine (RDX); 1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX); or even 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20). At the same time, they are less sensitive than RDX, HMX, and CL-20, making them potential candidates for high-energy density compounds.