cis-1,3,4,6-Tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX), its properties and initiation reactivity

Using the 15N NMR chemical shifts of nitrogen atoms in nitramino groups of cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole (bicyclo-HMX or BCHMX) and additional 10 nitramines, we have assessed its reactivity in detonation, under the influence of impact, and by action of electric spark. It is stated that the thermal stability of BCHMX is higher than that of 1,3,5-trinitro-1,3,5-triazinane (RDX). The longest N-N bond in the BCHMX molecule (1.412(4) A) is the cause for its higher impact reactivity, which is at the level of that of penterythritol tetranitrate (PETN). In the experimentally determined detonation velocity, BCMX can be slightly better performing than RDX. From the standpoint of friction sensitivity, BCHMX is similar to 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX). Attention was also focused on the solubility-temperature dependence of BCHMX in acetone, acetonitrile, ethyl acetate, dimethyl sulfoxide, tetrahydrofurane, and nitromethane. X-ray crystallographic study of BCHMX (C4H6N8O8, Mr = 294.17), has been carried out at the temperature of 150 K with the following results: a = 8.5430(8), b = 6.9480(6), c = 8.7780(8) A, α = 90.0(7)o, β = 102.452(11)o, γ = 90.0(9)o, V = 508.777(8) A3, Z = 2, Dx = 1.920 g cm-3, λ(Mo Ka) = 0.71073 A, μ = 0.169 cm-1, F(000) = 856, final R = 0.0414 for 1254 independent observed reflections. In the BCHMX crystal there were found more short contacts in the molecular crystal of BCHMX data of Gilardi creating extensive supramolecular architecture.