Nitrogen-Rich Tetrazolium Azotetrazolate Salts: A New Family of Insensitive Energetic Materials

Abstract

The metathesis reaction of sodium azotetrazolate with tetrazolium iodides 5and 6 at reflux in water yielded dihydrated species in both instances (1 and 3, respectively). However, when silver azotetrazolate (Ag2ZT) was used instead of the sodium salt in dry methanol, the anhydrous compounds 2 and 4 formed. An alternative synthesis for 2 and 4 that avoids handling highly sensitive Ag2ZT is introduced. All materials were fully characterized by means of elemental analysis, mass spectrometry (MS), and vibrational (IR, Raman) and NMR (1H, 13C) spectroscopy. Additionally, the crystal structures of the new compounds were determined (1, monoclinic, P21/c; 2–4, triclinic,P1̅). A discussion of the hydrogen bonding by means of graph-set analysis is provided. The thermal behaviors of 1–4 and their constant volume energies of combustion were assessed by DSC and bomb calorimetry measurements, respectively. Their sensitivity to shock, friction, and electrostatic discharge was measured by submitting the compounds to standard tests. The detonation pressures and velocities were calculated from the energies of formation using the EXPLO5 code (1, P = 20.2 GPa, D = 7820 m s−1; 2, P = 20.0 GPa, D = 7803 m s−1; 3, P = 22.4 GPa, D = 8090 m s−1; and 4, P = 21.1 GPa, D = 7977 m s−1. Lastly, the decomposition products were both calculated and experimentally determined.