Nitrogen-Rich Tetrazolo[1,5‑b]pyridazine: Promising Building Block for Advanced Energetic Materials

Two metal-free explosives, tetrazolo­[1,5-b]­pyridazine-containing molecules [6-azido-8-nitrotetrazolo­[1,5-b]­pyridazine-7-amine (3at) and 8-nitrotetrazolo­[1,5-b]­pyridazine-6,7-diamine (6)], were obtained via straightforward two-step synthetic routes from commercially available reagents. Compound 3at displays an excellent detonation performance (D_v = 8746 m s^–1 and P = 31.5 GPa) that is superior to commercial primary explosives such as lead azide and diazodinitrophenol (DDNP). Compound 6 has superior thermal stability, remarkable insensitivity, and good detonation performance, strongly suggesting it as an acceptable secondary explosive. The initiating ability of compound 3at has been tested by detonating 500 mg of RDX with a surprisingly low minimum primary charge of 40 mg. The extraordinary initiating power surpasses conventional primary explosives, such as commercial DDNP (70 mg) and reported 6-nitro-7-azido-pyrazol­[3,4-d]­[1,2,3]­triazine-2-oxide (ICM-103) (60 mg). The outstanding detonation power of 3at contributes to its future prospects as a promising green primary explosive. In addition, the environmentally benign methodology for the synthesis of 3at effectively shortens the time from laboratory-scale research to practical applications.