One-Pot Synthesis, Crystal Structure, and Thermal Decomposition Behavior of 1,1ʹ-Diamino-4,4ʹ,5,5ʹ-Tetranitro-2,2ʹ-Biimidazole

1,1ʹ-Diamino-4,4ʹ,5,5ʹ-tetranitro-2,2ʹ-biimidazole (DATNBI) was synthesized, by employing one-pot facile method, from 4,4ʹ,5,5ʹ-tetranitro-2,2ʹ-biimidazole. The crystal structure was determined by X-ray diffraction for the first time. DATNBI crystallized in monoclinic system P2₁/c, with a crystal density of 1.934 g cm⁻³ at 293(2) K and 2.019 g cm⁻³ at 130(2) K, respectively. Its crystal parameters at 293 K are a = 4.8833(15) Å, b = 6.960(2) Å, c = 6.928(4) Å, α = γ = 90°, β = 93.418(6)°, V = 591.1(3) Ǻ³, Z = 2, μ = 0.178 mm⁻¹, and F(000) = 348. The thermal stability and non-isothermal kinetics of DATNBI were studied by differential scanning calorimeter (DSC) with heating rates of 5, 10, 15, and 20 K min⁻¹. The apparent activation energy (E_a) at the first decomposition peak calculated by Kissinger, Ozawa, and Starink equations were 85.50, 89.67, and 86.10 kJ mol⁻¹, respectively. For the second peak, these were 116.49, 119.82, and 117.45 kJ mol⁻¹, respectively, with individual pre-exponential factors lnA = 18.40 s⁻¹ and lnA = 25.11 s⁻¹. The thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) analysis of thermal decomposition products reveals that the main decomposition gas products are H₂O, N₂O, CO₂, and NO₂. Based on the new crystalline densities, the detonation velocity and pressure predicted by EXPLO5 are 9062 m s⁻¹ and 36.4 GPa, respectively.