Synthesis and characterization of multicyclic oxadiazoles and 1-hydroxytetrazoles as energetic materials

Synthesis and characterization of several multicyclic oxadiazoles, 3,5-bis(4-nitrofurazan-3-yl)-1,2,4-oxadiazole, 3,3'-bis(4-nitrofurazan-3-yl)-5,5'-bi(1,2,4-oxadiazole), 3-(4-nitrofurazan-3-yl)-1,2,4-oxadiazol-5-amine, and salts of 1-hydroxytetrazoles, ammonium 5,5'-(1,2,4-oxadiazole-3,5-diyl)bis(1H-tetrazol-1-olate) and hydroxylammonium 5,5'-{[3,3'-bi(1,2,4-oxadiazole)]-5,5'-diyl}bis(1H-tetrazol-1-olate), as energetic materials are reported. Two of the compounds, 3,5-bis(4-nitrofurazan-3-yl)-1,2,4-oxadiazole and 3,3'-bis(4-nitrofurazan-3-yl)-5,5'-bi(1,2,4-oxadiazole), have attractive single crystal densities of 1.91 and 1.94 g·cm–3 (at 20°C), respectively. The design of these materials has been based on the idea that these multicyclic compounds with a 1,2,4-oxadiazole core will have good thermal stability and high density because of their 3,5-substitution pattern and the possibility of achieving a planar conformation. The various synthetic approaches and interesting chemistry observed during the construction of these new heterocycles has been described.