Crystal structure of poly[(2,2 '-bipyridine-kappa N-2,N')-tetrakis(mu-cyanido-kappa N-2:C)dinickel(II)]

The polymeric title complex, [Ni-2(CN)(4)(CiOH(8)N(2))](n), was obtained serendipitously under hydrothermal conditions. The asymmetric unit consists of one half of an [Ni(CN)(4)](2-) anion with the Ni2+ cation situated on an inversion centre, and one half of an [Ni(2,21-bpy)](2+) cation (2,2'-bpy is 2,2'-bipyridine), with the second Ni2+ cation situated on a twofold rotation axis. The two Ni2+ cations exhibit different coordination spheres. Whereas the coordination of the metal in the anion is that of a slightly distorted square defined by four C-bound cyanide ligands, the coordination in the cation is that of a distorted octahedron defined by four N -bound cyanide ligands and two N atoms from the chelating 2,2'-bpy ligand. The two different Ni2+ cations are alternately bridged by the cyanide ligands, resulting in a two-dimensional structure extending parallel to (010). Within the sheets, 7r-rr interactions between pyridine rings of neighbouring 2,2'-bpy ligands, with a centroid-to-centroid distance of 3.687 (3) angstrom, are present. The crystal packing is dominated by van der Waals forces. A weak C H" " "N interaction between adjacent sheets is also observed.