Nitrogen-Rich Ligands Directed Transition Metal (Co/Ni/Zn) 3,5-Dinitrobenzoic Acid Energetic Complexes: Syntheses, Crystal Structures and Properties

Energetic transition metal (Co/Ni/Zn) complexes based on 3,5-dinitrobenzoic acid (DNBA), 1,5-diaminotetrazole (DAT), and semicarbazide (SCZ) were synthesized and characterized by elemental analysis and IR spectroscopy. The structures of the nine complexes were confirmed by single-crystal X-ray diffraction as: [Co(DNBA)(2)(H2O)(4)4(H2O)] (1), [Ni(DNBA)(2)(H2O)(4)4(H2O)] (2), [Zn(DNBA)(2)](n) (3), Co(SCZ)(2)(DNBA)(2) (4), Ni(SCZ)(2)(DNBA)(2) (5), Zn(SCZ)(2)(DNBA)(2) (6), Co(DAT)(2)(DNBA)(2)(H2O)(2) (7), Ni(DAT)(2)(DNBA)(2)(H2O)(2) (8), Zn(DAT)(2)(DNBA)(2)(H2O)(2) (9). It is worth mentioning that 3 exhibits a fascinating trigonal helical chain architecture bridged along the c-axis by Zn(II) and carboxylic O atoms. Differential scanning calorimetry (DSC) and thermogravimetry (TG) analyses were applied to assess the thermal decomposition processes and the non-isothermal kinetics parameters. The decomposition temperatures of 1-9 are in the range of 190 degrees C to 374 degrees C, which of 1, 2 and 3 are higher than 350 degrees C, 7 possesses the lowest decomposition temperatures. The nitro-rich ligands advanced the thermal decompositions of these complexes. The sensitivities toward impact and friction were tested according to a standard BAM method, and resulting that all the energetic complexes are much lower sensitive than primary explosive lead azide.