Synthesis, Characterization, and Properties of Novel Coplanar Bicyclic Compounds Based on Triazolofurazane Compounds

In this study, a C-C bond-linked triazole-fused oxadiazole energetic compound, 4-amino-5-(4-amino-1,2,5-oxadiazol-3-yl)-2,4-dihydro-3<i>H</i>-1,2,4-triazol-3-one (<b>1</b>), was successfully designed and efficiently synthesized. Following nitration, a functional group-modified nitramine energetic compound (<b>2</b>) was obtained, and its energetic ionic salt (<b>3</b>) was further prepared. A comprehensive characterization of the structures of these three compounds was conducted, resulting in the successful elucidation of the single-crystal structures of compound <b>2</b>·Ca²⁺·6H₂O and compound <b>3</b>·MeOH. Compound <b>2</b> exhibited a positive formation enthalpy (56.2 kJ·mol^-1) and moderate mechanical sensitivity (FS = 120 N, IS = 12 J). Due to the presence of the nitramine group, compound 2 exhibited a relatively low thermal decomposition temperature (<i>T</i>_dec = 94 °C). However, the thermal stability of compound <b>3</b> was significantly improved (<i>T</i>_dec = 233 °C), which is attributed to salt formation. Compound <b>3</b> exhibits a positive formation enthalpy (121.0 kJ·mol^-1), along with excellent detonation performance (D = 8120 m·s^-1, P = 32.1 GPa) and reduced mechanical sensitivity (FS = 224 N, IS = 24 J). Therefore, the multi-heterocyclic compound, joined via C-C bond linkage, demonstrates outstanding performance, offering a new avenue for the design and synthesis of energetic materials.