The Triply Deprotonated Acetonitrile Anion CCN3− Stabilized in a Solid

The unprecedented, fully deprotonated form of acetonitrile, the acetonitriletriide anion CCN³⁻, is experimentally realized for the first time in the stabilizing bulk host framework of the Ba₅[TaN₄][C₂N] nitridometalate via a one‐pot synthesis from the elements under moderate conditions (920 K). The molecular structure of this long‐sought acetonitrile derivative is confirmed by X‐ray diffraction, as well as NMR, IR, and Raman spectroscopy. The anion is isoelectronic to the CO₂ molecule, and, in contrast to acetonitrile (H₃C−C≡N), the electron pairs are shifted towards two double bonds, that is, [C=C=N]³⁻.