Bistetrazoles: Nitrogen-Rich, High-Performing, Insensitive Energetic Compounds

Large-scale syntheses of nitrogen-rich 5,5′-hydrazinebistetrazole (HBT) (or 1,2-ditetrazolylhydrazine) and bis(3,4,5-triamino-1,2,4-triazolium) 5,5′-azotetrazolate (G2ZT) with high yields and purities on a multigram scale are introduced. DSC analysis showed good thermal stabilities for both materials (>200 °C) and their long-term stabilities were assessed by TSC (thermal safety calorimetry). Because molecular structures play an important role in the properties of an energetic material, hydrogen bonding in both compounds is described in terms of graph-set analysis. The extensive hydrogen bonding in the structures seems to account for their relatively high densities (HBT, ρ = 1.841 g cm−3; and G2ZT, ρ = 1.708 g cm−3). The heats of combustion of the two compounds were calculated (ΔcU°(HBT) = −2396 cal g−1 and ΔcU°(G2ZT) = −2775 cal g−1) and combined with the experimentally determined densitites (X-ray) and the molecular formulas to calculate the detonation pressures (P) and velocities (D) using the EXPLO5 computer-code (HBT, P = 27.7 GPa, D = 8523 m s−1; and G2ZT, P = 19.9 GPa, D = 7683 m s−1). The sensitivity of both materials to shock, friction and electrostatic discharge was assessed using standard BAM tests, revealing very stable compounds (HBT, shock >30 J, friction >108 N; and G2ZT, shock >30 J, friction >360 N) with no sensitivity toward an electrostatic discharge of ∼20 kV. In addition, the explosion/decomposition gases were experimentally measured by means of IR spectroscopy and mass spectrometry and are compared with the explosion/decomposition gases calculated using the ICT thermodynamic code. With high nitrogen contents (∼80%), the reported bistetrazoles are prospective new, environmentally friendly, high-performance energetic materials with low sensitivities and good thermal stabilities that might find use as solid propellants or in propellant charges.