Tris(ethylenediamine)nickel(II) bis[2-cyano-2-(oxidoimino)acetamidato]nickelate(II) monohydrate

The title compound, [Ni(C2H8N2)(3)][Ni(C3HN3O2)(2)]center dot H2O, appears to be a modular associate consisting of two complex counter-ions, containing bivalent nickel as the central atom in both cases, and a solvent water molecule. The Ni-II ion in the complex cation lies on the C-2 crystallographic axis. Its coordination environment is formed by six N atoms of three ethylenediamine (en) molecules, representing a distorted octahedral geometry. The Ni-II ion in the complex anion occupies a position at the center of inversion. It exhibits a distorted square-planar coordination geometry formed by four N atoms belonging to the deprotonated oxidoimine and amide groups of the two doubly charged 2-cyano-2-(oxidoimino)acetamidate anions, situated in trans positions with respect to each other. In the crystal packing, the complex anions are linked by water molecules via hydrogen bonds between the amide O atoms and water H atoms, forming chains translated along the a direction. The [Ni(en)(3)](2+) cations fill empty spaces between the translational chains, connecting them by hydrogen bonds between the oxime and amide O atoms of the anions and the amine H atoms of the cations, forming layers along the ac plane. The water molecules provide connection between layers through N atoms of the cations, thus forming a three-dimensional modular structure.