5-(4-Azidofurazan-3-yl)-1-hydroxytetrazole and its derivatives: from green primary to secondary explosives

5-(4-Azidofurazan-3-yl)-1-hydroxytetrazole (4) and its ammonium (4a), hydroxylammonium (4b), and hydrazinium (4c) salts were synthesized. Each compound was characterized by X-ray single crystal structure diffraction, infrared (IR), and H-1 and C-13 NMR spectroscopy, elemental analyses, thermal stability, and sensitivity to external stimulants. Crystal structures and packing coefficients were analyzed and compared with respect to pi-pi stacking and hydrogen bonding. Due to the presence of lattice water in compound 4, the impact sensitivity (IS = 15 J) and friction sensitivity (FS = 120 N) are notably lower than those of the anhydrous material (IS = 3 J, FS = 20 N), which could act as a primary explosive. In this way, the primary explosive could be synthesized, transported, and stored more safely than traditional primary explosives. The detonation properties determined by EXPLO 6.02 software show that among the four compounds, 4b has superior detonation velocity (V-d = 9201 m s(-1)) and pressure (P = 36.0 GPa) values which are comparable to those of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine). The impact sensitivity (10 J) is less-sensitive than HMX (7.5 J), which suggests compound 4b as a potential alternative to HMX.