Synthesis and Crystal Structure of Ammonium Cyanimide NH4HCN2

The compound NH₄HCN₂ ( 1 ) was prepared by the reaction of H₂CN₂ with liquid ammonia. The ammonium salt 1 was characterized by a low temperature single‐crystal X‐ray structure analysis. The anionic part of the structure consists of HCN₂^? anions, which are connected via N–H···N bonds (H···N distance: 2.47Å, DHA: 165°). The N–H···N hydrogen bonds of the ammonium ion to the anions range from 2.00 to 2.14Å (DHA = Donor···Acceptor angles: 165–176°), all N–H···N interactions together give rise to a three‐dimensional network. 1 decomposes quantitatively to dicyandiamide at room temperature.