Abstract

The structure of the title compound, NiCu(CN)4(C10H8N2)(H2O)2n or {Cu(H2O)2}(-C10H8N2)(-CN)2{Ni(CN)2}n, was shown to be a metal-organic cyanide-bridged framework, composed essentially of -Cu-4,4'-bpy-Cu-4,4'-bpy-Cu- chains (4,4'-bpy is 4,4'-bipyridine) linked by Ni(CN)42- anions. Both metal atoms sit on special positions; the CuII atom occupies an inversion center, while the NiII atom of the cyanometallate sits on a twofold axis. The 4,4'-bpy ligand is also situated about a center of symmetry, located at the center of the bridging C-C bond. The scientific impact of this structure lies in the unique manner in which the framework is built up. The arrangement of the -Cu-4,4'-bpy-Cu-4,4'-bpy-Cu- chains, which are mutually perpendicular and non-intersecting, creates large channels running parallel to the c axis. Within these channels, the Ni(CN)42- anions coordinate to successive CuII atoms, forming zigzag -Cu-NC-Ni-CN-Cu- chains. In this manner, a three-dimensional framework structure is constructed. To the authors' knowledge, this arrangement has not been observed in any of the many copper(II)-4,4'-bipyridine framework complexes synthesized to date. The coordination environment of the CuII atom is completed by two water molecules. The framework is further strengthened by O-HN hydrogen bonds involving the water molecules and the symmetry-equivalent nonbridging cyanide N atoms.