C-H center dot center dot center dot Ni interactions and cyano-bridged heteronuclear polymeric complexes studied by vibrational spectroscopy and quantum chemistry calculations

Abstract

Three 1D bimetallic M(II)/Ni(II) (M = Cu, Zn and Cd) complexes, [Cu(OHepy)(2)Ni(CN)(4)] (1), [Zn(OHepy)(2)Ni(CN)(4)] (2) and [Cd(OHepy)2Ni(CN)4](n) (3) (2-(2-hydroxyethyl)pyridine abbreviated to OHepy), have been synthesized and characterized by FT-IR and Raman spectroscopy, elemental, thermal analyses and single crystal X-ray diffraction techniques. FT-IR and Raman spectra of OHepy have been experimentally and theoretically investigated in the region of 4000-250 cm(-1). The corresponding vibrational assignments of OHepy are examined by means of B3LYP hybrid density functional theory (DFT) method together with 6-311++G(d, p) basis set. Moreover, reliable vibrational assignments have been made on the basis of potential energy distribution (PED). The structures of the complexes consist of one-dimensional polymeric chain -M(OHepy)(2)-NC-Ni(CN)(2)-CN-M(OHepy)(2-), in which the M(II) and Ni(II) atoms are linked by CN groups. The nickel atom is fourfold coordinated with four cyanide-carbon atoms in a square planar arrangement and the metal(II) atoms are sixfold coordinated with two cyanide nitrogen, two OHepy nitrogen and two OHepy oxygen atoms, in a distorted octahedral arrangement. In all the complexes adjacent chains are connected by pi...pi C H...Ni and O-H...N hydrogen bonding interactions to form two and three dimensional networks. (C) 2014 Elsevier B.V. All rights reserved.