A hybrid of tetrazolium and pentazolate: An energetic salt with ultrahigh nitrogen content and energy

As a full nitrogen energetic anion, pentazolate (cyclo-N₅ˉ) holds great promise in the fields of propellants and explosives. Nowadays, nonmetallic pentazolate salts have received extensive attention as excellent nitrogen-rich energetic materials for their high enthalpies of formation, good oxygen balance, and eco-friendly decomposition products. In this study, a 1,4,5-triaminotetrazolium-based pentazolate salt (TATe⁺N₅ˉ, 8) with a nitrogen content of up to 90.30% was designed and synthesized. Its crystal structure indicates that a large number of hydrogen bonds form a hydrogen-bonded network, and the crystal has a mixed stacking pattern. TATe⁺N₅ˉ, which has a relatively high density (1.64 ​g·cm⁻³), high heat of formation (861.9 ​kJ·mol⁻¹), and excellent detonation performances (detonation velocity: 9487 ​m·s⁻¹, detonation pressure: 32.5 ​GPa), provides new insights into the stability of ultrahigh-nitrogen compounds.