Crystal structure of the 1:1 cocrystal 5,5'-(triaz-1-ene-1,3-di-yl)bis-(3-nitro-1H-1,2,4-triazole)-tri-ethylammonium nitrate.

The tri-ethyl-ammonium nitrate cocrystal of 5,5'-(triaz-1-ene-1,3-di-yl)bis-(3-nitro-1H-1,2,4-triazole), C(4)H(3)N(11)O(4)·C(6)H(16)N·NO(3) (3), was obtained unintentionally as the product of an attempted synthesis of a heterocyclic C-bromo-nitrilimine from 3-amino-5-nitro-1,2,4-triazole (ANTA). In the solid state at 150†K, the structure of 3 is modulated by a pseudo-translation along [010] with Z* = 4 (Z = 8 in P1). Exact translational symmetry is broken by a slight modulation of the triazene mol-ecules and nitrate anions, and by disorder of two of the four tri-ethyl-ammonium cations. An extensive hydrogen-bonding network connects the components of the structure and enables a relatively high density of 1.516†g†cm(-3). This feature, as well as its high nitro-gen content, make this rare triazene-bridged 1,2,4-triazole and possible related similar compounds of inter-est as potential energetic materials.