C2N14: an energetic and highly sensitive binary azidotetrazole.

Although binary CN compounds are of great interest, only a few examples are known, which is mostly due to the fact that their chemistry is very challenging. Binary CN compounds exhibit a large variety of characteristics; they can be very harmful owing to their toxicity, such as dicyanogen, and they are thought to be very hard, as calculated for b-C3N4, [2] or show graphite-like nanostructures with good electric and catalytic properties, such as mpg-C3N4. [3] Furthermore, binary CN compounds composed of azides are highly sensitive towards shock, friction, and electrostatic discharge. Investigations on these compounds started at the beginning of the 20th century when Ott and Ohse presented C3N12 in 1921 (Scheme 1) as the first binary azido heterocyclic system. Research into heterocyclic azides was recently intensified, as they present very good systems to study highly energetic materials enabled by high positive heats of formation. The high heats of formation derive from the energy input of the azide substituents (70 kJmol ) and from the large number of energetic N N and C N bonds combined in the heterocyclic ring systems. Non-heterocyclic binary CN systems have also attracted much interest, such as tetraazidomethane, which has an extreme sensitivity towards shock and friction, or the open form of the title compound C2N14, isocyanogentetraazide, [9] which is somewhat less sensitive than the title compound. To date, only the open form of C2N14 was known, which can be synthesized by a metathesis reaction of isocyanogentetrabromide with sodium azide. Herein, the synthesis of the closed form of C2N14, 1-diazidocarbamoyl-5-azidotetrazole (1), is presented for the first time, being synthesized by diazotation of triaminoguanidinium chloride in water with two equivalents of sodium nitrite. A suggested mechanism of this reaction is presented in Scheme 2.