Nickel(II)⋯π interaction in [M(ampy)2Ni(μ-CN)2(CN)2]n (M = Zn(II) and Cd(II), ampy = 2-aminomethylpyridine): Syntheses, vibrational spectroscopy, thermal analyses and crystal structures of cyano-bridged heteronuclear polymeric complexes

Two novel three-dimensional cyano-bridged heteronuclear polymeric complexes, [Zn(ampy)2Ni(μ-CN)2(CN)2]n (1) and [Cd(ampy)2Ni(μ-CN)2(CN)2]n (2), (ampy = 2-aminomethylpyridine or 2-picolylamine, C6H8N2) were synthesized and characterized by FT-IR spectroscopy, thermal analyses (TG, DTG and DTA), elemental analyses and single crystal X-ray diffraction techniques. Vibration assignments were given for all the observed bands and the spectral feature also supported to the structure of polymeric complexes. The Ni(II) ion is four coordinate with four cyanide–carbon atoms in a square planar geometry and the Zn(II) or Cd(II) ion exhibits a distorted octahedral coordination by two bidentate ampy ligands and two bridging cyano groups as a cis position. In additional, there are also interaction between Ni(II) ion and the aromatic π-system. The structures of 1 and 2 are similar and consist of 1-D zigzag chains which are linked via intermolecular hydrogen bonding, C–H⋯π and Ni(II)⋯π interactions to give rise to 3-D networks.