Energetic transition metal salts of 5,5′-dinitramino-3,3′-methylene-1H-1,2,4-bistriazole: syntheses, structures and properties

Abstract

Nitrogen-rich energetic compound 5,5′-dinitramino-3,3′-methylene-1H-1,2,4-bistriazole (H₂DNAMT (1)) and its transition metal salts, including [Co(DNAMT)(H₂O)₄]·2H₂O (2), [Ni(DNAMT)(H₂O)₄]·2H₂O (3), [Zn(DNAMT)(H₂O)₄]·2H₂O (4), [Cd(DNAMT)(H₂O)₄]·2H₂O (5) and [Fe(BNATO)(H₂O)₄]·2H₂O (6), were synthesized and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction analysis. The crystal structures of compounds 2–5 are similar, and crystallize in orthorhombic systems with the Pnma space group, whereas compound 6 belongs to the orthorhombic system with the Pccn space group. The densities of these salts are in the range of 1.832 (compound 2) to 1.999 g cm⁻³ (compound 5). In compound 6, H₂DNAMT was oxidized to bis(3-nitroimino-2H-1,2,4-triazole-5-yl)methanone (H₂BNATO) due to the trivalent iron anion. The NBO charge of H₂DNAMT and BNATO²⁻ was calculated by density functional theory, to understand their coordination modes. The thermal decomposition processes, non-isothermal kinetics, enthalpies of formation and sensitivities of these compounds were investigated in detail to argue their potential application as energetic materials.