In the chemical zoo this week: CCN three minus, that is acetonitrile stripped of all its protons as reported by Jach et al. in The Angewandte (DOI). The recipe was unsurprisingly complex: a mixture of barium nitride (made from barium and nitrogen at 550K), elemental tantalum, sodium azide and graphite was reacted at at 920 K for 24 hours forming solid Ba5(TaN4)(C2N) as orange plates. The necessity of the sodium azide is not explained, the article only mentions that after the reaction all nitrogen has evaporated and that sodium metal did assemble at the top of the reaction vessel. Hydrolysis yields acetonitrile again. The lab was stocked with X-ray diffraction, solid-state NMR spectroscopy, ironically named INADEQUATE AND REDOR for full analysis. In the crystal structure layers of CCN and barium alternate with nitridometalate layers. QTAIM suggests two double bonds (C=C=N) in the structure.