Thermally Stable 3,6-Dinitropyrazolo[4,3-c]pyrazole-based Energetic Materials

3,6-Dinitropyrazolo[4,3-c]pyrazole was prepared using an efficient modified process. With selected cations, ten nitrogen-rich energetic salts and three metal salts were synthesized in high yield based on the 3,6-dinitropyrazolo[4,3-c]pyrazolate anion. These compounds were fully characterized by IR and multinuclear NMR spectroscopies, as well as elemental analyses. The structures of the neutral compounds4 and its salt 16 were confirmed by single-crystal X-ray diffraction showing extensive hydrogen-bonding interactions. The neutral pyrazole precursor and its salts are remarkably thermally stable. Based on the calculated heats of formation and measured densities, detonation pressures (22.5-35.4GPa) and velocities (7948-9005ms(-1)) were determined, and they compare favorably with those of TNT and RDX. Their impact and friction sensitivities range from 12 to >40J and 80 to 360N, respectively. These properties make them competitive as insensitive and thermally stable high-energy density materials.