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 compounds 4 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 (22.5-35.4 GPa) and velocities (7948-9005 m s(-1)) were determined, and they compare favorably with those of TNT and RDX. Their impact and friction sensitivities range from 12 to >40 J and 80 to 360 N, respectively. These properties make them competitive as insensitive and thermally stable high-energy density materials.