Syntheses, crystal structures and spectral properties of 1D tetracyanonickelate(II) complexes with 1-ethylimidazole

Three new cyano-bridged tetracyanonickelate(II) complexes with 1-ethylimidazole (etim) ligand, [Ni(etim)4Ni(μ-CN)2(CN)2]n (1), [Zn(etim)4Ni(μ-CN)2(CN)2]n (2) and {[Cd(etim)4Ni(μ-CN)2(CN)2]2·2H2O}n (3) have been synthesized and characterized by spectroscopic (IR and Raman) and X-ray diffraction techniques. According to the crystallographic data, it was understood that the complexes with the chain 2,2-TT structures belong to P−1 space group of triclinic crystal system. In the complexes, it was observed that Ni(II), Zn(II) and Cd(II) ions have distorted octahedral geometries. In the [Ni(μ-CN)2(CN)2]2− anion, the Ni(II) ion is coordinated by the four carbon atoms of the four cyano ligands, and exhibits square-planar coordination geometry. The crystallographic analyses reveal that the crystal structures of complexes 1–3 are one dimensional linear chain polymers and these chains are held together by the CH⋯π, CH⋯Ni and hydrogen bonding interactions, forming three-dimensional networks.