Synthesis of Pentazolate Salts Based on Methenamine Cage-like Cations

Based on two urotropine cage-like cationic structures, two new pentazolate salts, urotropine pentazolate salt (C6H13N9, 1)and methylated urotropine pentazolate salt (C7H15N9, 2), were synthesized. The synthesized pentazolate salts were structurally characterized by X-ray single crystal diffraction, infrared spectroscopy(IR), mass spectrometry(MS)and nuclear magnetic resonance (NMR), and were analyzed by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) to evaluate their thermal decomposition behaviors. The formation enthalpy of compound 1 and 2 was calculated using the atomization method, the detonation performance was predicted using EXPLO5, and the impact sensitivity and friction sensitivity were tested using the BAM method. The results show that compound 1 belongs to the monoclinic crystal system (P21/c), and the crystal cell parameters are a=13.6795(2)Å, b=11.6892(1)Å, c=12.5941(2)Å, V=1937.53(5)Å3, α=γ= 90°, β=105.822(1)°, Z=8, Dc=1.448 g·cm-3;compound 2 belongs to the monoclinic crystal system (P21/m), and the crystal cell parameters are a=6.9025(5)Å, b=7.6042(5)Å, c=10.6808(9)Å, V=538.50(7)Å3, α= γ=90°, β=106.148(8)°, Z=2, Dc=1.389 g·cm-3. The thermal decomposition temperature of compound 1 is 90.0 ℃, and 82.8 ℃ for compound 2. The detonation velocity and pressure of compound 1 and 2 are 8291 m·s-1 and 20.33 GPa, 7862 m·s-1 and 17.41 GPa, respectively. While the measured impact sensitivity and friction sensitivity of compound 1 and 2 are 5 J and 288 N, 3 J and 86 N, respectively. © 2024 Institute of Chemical Materials, China Academy of Engineering Physics. All rights reserved.