CH⋯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)<inf>2</inf>Ni(CN)<inf>4</inf>]<inf>n</inf> (1), [Zn(OHepy) <inf>2</inf>Ni(CN)<inf>4</inf>]<inf>n</inf> (2) and [Cd(OHepy) <inf>2</inf>Ni(CN)<inf>4</inf>]<inf>n</inf> (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) <inf>2</inf>NCNi(CN)<inf>2</inf>CNM(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 π⋯π, CH⋯Ni and OH⋯N hydrogen bonding interactions to form two and three dimensional networks. © 2014 Elsevier B.V. All rights reserved.