Tetra­methyl­ammonium (Z)-N′-cyano­carbamimidate

In the structure of the tetra­methyl ammonium salt of cyano­urea, C(4)H(12)N(+)·C(2)H(2)N(3)O(−), the N—C and O—C bond distances in the cyano and keto groups are in the normal range for such a moieties at 1.1641 (18) and 1.2550 (16) Å. However, the bonds about the central C and N atoms are much shorter than would be expected for single bonds and indicate that there is considerable electron delocalization in the anion as was also found in the silver salt. The NH(2) group is coplanar with the central N(2)CO core, in contrast with the nitrile group where the dihedral angle between the N—C—N and N(2)CO planes is 36.5 (3)°. The packing of the cations and anions in the unit cell involves N—H⋯O hydrogen bonds between anions characterized by an R (2) (2)(8) motif, as well as N—H⋯O hydrogen bonds between anions and C—H⋯O inter­actions between both cations and anions, forming an R (3) (3)(14) pattern. [Image: see text]