Synthesis, crystal structure and properties of a new 1D polymeric nitrogen-rich energetic complex {TAG[Li(BTO)(H2O)]}n based on 1H,1′H-5,5′-bitetrazole-1,1′-diolate

Abstract

A novel energetic coordination polymer, or a new anionic metal–organic framework (MOF), of {TAG[Li(BTO)(H₂O)]}_n based on 1H,1′H-5,5′-bitetrazole-1,1′-diolate (BTO), was developed based on the reaction of BTO with triaminoguanidinium chloride (TAG·HCl) and lithium hydroxide (LiOH), and characterized by elemental analysis and IR spectroscopy. The crystal structure was determined by single-crystal X-ray diffraction measurements. Results show that the polymer belongs to the monoclinic space group C/2c with a density of 1.678 g cm⁻³, and the cell parameters were as follows: a = 15.6560(5) Å, b = 6.3323(19) Å, c = 23.8140(7) Å, β = 91.342(3)°, V = 2360.20(12) ų, Z = 8, F(000) = 1232. The central lithium cation was coordinated by two N atoms, two O atoms from BTO ligands, and the O atom from one coordination water molecule. The infinite 1D-zigzag-chains were made up of the central lithium cations linked by bridging-chelating BTO ligands. The thermal decomposition of {TAG[Li(BTO)(H₂O)]}_n was studied based on technologies of differential scanning calorimetry (DSC) and thermogravimetry-differential thermogravimetry (TG-DTG). The non-isothermal kinetics parameters were calculated through the Kissinger and the Ozawa–Doyle methods, and the apparent activation energy was 236.6 kJ mol⁻¹ and 233.1 kJ mol⁻¹, while the critical temperature of thermal explosion was 231.6 °C. The enthalpy of formation for the polymer was also determined through the combustion heat data, measured by using oxygen bomb calorimetry, as 29.5 kJ mol⁻¹. Additionally, the sensitivities towards impact and friction were assessed with relevant standard methods, the results show that the polymer can act as an insensitive explosive with its high nitrogen-content.