Energetic Derivatives of 4, 4′,5, 5′-Tetranitro-2, 2′-bisimidazole (TNBI)

4, 4′,5, 5′-Tetranitro-2, 2′-bisimidazole (TNBI) was synthesized by nitration of bisimidazole (BI) and recrystallized from acetone to form a crystalline acetone adduct. Its ammonium salt (1) was obtained by the reaction with gaseous ammonia. In order to explore new explosives or propellants several energetic nitrogen-rich 2:1 salts such as the hydroxylammonium (3), guanidinium (4), aminoguanidinium (5), diaminoguanidinium (6) and triaminoguanidinium 7 4, 4′,5, 5′-tetranitro-2, 2′-bisimidazolate were prepared by facile metathesis reactions. In addition, methylated 1, 1′-dimethyl-4, 4′,5, 5′-tetranitro-2, 2′-bisimidazole (Me2TNBI, 8) was synthesized by the reaction of 2 and dimethyl sulfate. Metal salts of TNBI can also be easily synthesized by using the corresponding metal bases. This was proven by the synthesis of pyrotechnically relevant dipotassium 4, 4′,5, 5′-tetranitro-2, 2′-bisimidazolate (2), which is a brilliant burning component e.g. in near-infrared flares. All compounds were characterized by single crystal X-ray diffraction, NMR and vibrational spectroscopy, elemental analysis and DSC. The sensitivities were determined by BAM methods (drophammer and friction tester). The heats of formation were calculated using CBS-4M electronic enthalpies and the atomization method. With these values and mostly the X-ray densities different detonation parameters were computed by the EXPLO5 computer code. Due to the great thermal stability and calculated energetic properties, especially guanidinium salt 4 could be served as a HNS replacement.