Synthesis of 5/6/5-fused tricyclic-cation-based cyclo-N5− salt with high density and heat of formation

Abstracts: Pentazolate anion (cyclo-N5−) containing compounds have attracted wide interest in recent years. In this paper, to explore the fantastic chemistry of cyclo-N5−, a novel polyamino 5/6/5-fused tricyclic-cation-based cyclo-N5− salt, 2,3,5,6-tetraamino-9-imino-5,9-dihydro-3H-bis([1,2,4]triazolo)[1,5-a:5′,1′-d][1,3,5]triazin-8-ium pentazol-1-ide (TABTT +N5−) was designed and synthesized. The chemical structures were determined by FTIR spectroscopy and single-crystal X-ray diffraction. TABTT +N5− exhibited a planar layer structure and a regular face-to-face layer stacking due to the strong hydrogen-bonding networks formed between polyamino 5/6/5-fused tricyclic and cyclo-N5−. TABTT +N5− exhibited acceptable thermal stability (Td: 106 ​°C), high density (1.638 ​g ​cm−3), high heat of formation (1078.122 ​kJ ​mol−1), and a good balance between energy and safety with high detonation performances (vD ​= ​8756 ​m ​s−1, p ​= ​26.03 ​GPa) and a low sensitivity (IS ​= ​25 ​J, FS ​= ​360 ​N), demonstrating the potential of nitrogen-rich cyclo-N5− salts as high energy materials.