Nitrogen-rich 4,4′-azo bis(1,2,4-triazolone) salts - The synthesis and promising properties of a new family of high-density insensitive materials

4,4′-Azo-bis(1,2,4-triazolone) (ZTO) based salts from alkaline (Li⁺, K⁺, Na⁺, and Cs⁺), alkaline earth metal salts (Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺) and hydrazinium salt were synthesized in a simple, straightforward manner and were characterized by IR and NMR spectroscopy, elemental analysis. The single-crystal X-ray diffraction of seven salts (Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, and N₂H₅⁺) are also reported. The X-ray structures show that in the title compounds, the metal atoms are bonded to the nitrogen and oxygen atoms in the bistetrazole ring to form a sandwich structure. In addition, the thermal stabilities of all the title compounds were determined using thermogravimetric-differential thermal analysis (TG-DTA). All these new materials exhibit excellent thermal stability, high density, acceptable detonation properties, and excellent insensitivity to impact (h₅₀ > 60 cm). In particular, the barium, caesium and strontium salts are of great interest as potential high-density insensitive materials.