Intramolecular Connections of Tetrazoles with N,N′‑Alkylene and Ether Bridges: Toward Energetic Materials with High Nitrogen and Thermal Stability

To date, there have been few reports on fused tricyclic compounds in the field of energetic materials. To take full advantage of the high heat of formation of tetrazoles (334 kJ mol–1), a series of fused [5,6,5]- and [5,7,5]-tricyclic energetic compounds were synthesized by using 1,2-dibromoethane, 1,3-dibromopropane, and bromo­(bromomethoxy)­methane for intramolecular connections with bistetrazoles. In this study, the heat resistance of H2BTD (T d = 318 °C) is the same as that of conventional heat-resistant explosive HNS (T d = 318 °C). However, the fused tricyclic energetic compounds H2BTP (V D = 8025 m s), H2BTD) (V D = 7750 m s–1), and H2BTO (V D = 8146 m s–1) exhibit higher detonation velocities than those of HNS (V D = 7612 m s–1), making them potentially interesting candidates for further research into new heat-resistant explosives. The successful construction of fused [5,6,5]- and [5,7,5]-tricyclic compounds provides an effective guide for the future design of novel HEDMs.