5,5',6,6'-Tetranitro-2,2'-bibenzimidazole: A Thermally Stable and Insensitive Energetic Compound.

A new energetic compound, namely a secondary explosive (5,5',6,6'-tetranitro-2,2'-bibenzimidazole, TNBBI) with high thermal stability is described. TNBBI is synthesized through direct nitration of 2,2'-bibenzimidazole with nitric acid. TNBBI decomposes exothermically at 394 °C without visible melting. The heat of combustion and the standard enthalpy of formation are determined experimentally. The detonation parameters calculated for the new compound are slightly lower than those for TNT. However, the combination of TNBBI's high decomposition temperature and low sensitivity make it a promising thermally stable energetic compound. The structure of the new compound is confirmed by NMR and IR spectroscopy.