Hydrazine 5,5′-bitetrazole-1,1′-diolate: a promising high density energetic salt with good properties

The development of new environmentally friendly energetic compounds with reasonable detonation performance and safety is a long-term target in energetic materials research. A new energetic eco-friendly salt of hydrazine 5,5′-bitetrazole-1,1′-diolate (HA·BTO) is developed based on the reaction of 1H,1′H-5,5′-bitetrazole-1,1′-diolate (BTO) with hydrazine hydrochloride (HA·HCl), and fully characterized. The monocrystal of the title salt is obtained and the structure is determined by powder X-ray diffraction and single crystal X-ray diffraction. Results show that the salt belongs to the triclinic space group P1̄ with a relatively high density of 1.912 g cm^-3 under 298 K. The properties of the salt are discussed in detail. The thermal decomposition behaviors of the salt are tested, indicating that the salt has good thermal stability with a decomposition temperature above 200 °C. The enthalpy of formation for the salt is dependent on the combustion heat date measured by oxygen bomb calorimetry with a result of 425.6 kJ mol^-1, which is the same level as TKX-50, and four times higher than that of RDX. The detonation pressure (P) and detonation velocity (D) of the salt are calculated as 8931 m s^-1 and 36.1 GPa, which are higher than those of RDX. In addition, the impact and friction sensitivities are tested through a relevant standard method with a result of 28 J and 120 N, which are better than those of TKX-50. We can draw the conclusion that the salt could provide a promising future in use as a kind of insensitive explosive alternative. The discovery also contributes significantly to the expansion and application of the chemistry of 1H,1′H-5,5′-bitetrazole-1,1′-diolate, as well as N-heterocyclic compounds.