Synthesis and thermal behavior of a fused, tricyclic pyridine-based energetic material: 4-amino-5-nitro-[1,2,5]oxadiazolo[3,4-: e] tetra-zolo[1,5- a] pyridine-3-oxide

A fused, tricyclic pyridine-based energetic material, 4-amino-5-nitro-[1,2,5]oxadiazolo[3,4-e]tetrazolo[1,5-a]pyridine-3-oxide (ANTP), was first synthesized through a two-step reaction from commercially available reagents with a total yield of 75%, namely the azidonation of 4-amino-2,6-dichloro-3,5-dinitropyridine with nitrogen elimination and ring closure, followed by another azidonation and azido-tetrazolo tautomerism. Its structure was determined by single X-ray diffraction. The crystal of ANTP is orthorhombic, with space group P2₁2₁2₁ with crystal parameters of a = 8.9130(18) Å, b = 14.057(3) Å, c = 6.5730(13) Å, V = 823.5(3) ų, and Z = 4, F(000) = 480. It exhibits a surprisingly high density (1.92 g cm^-3 at 293 K), low thermal stability, a positive heat of formation and good detonation properties.