Solid-state vibrational spectroscopy. Part V. An infrared and Raman spectroscopic study of metal(II) halide pyridine complexes

Abstract

Infrared (200–4 000 cm^–1) and Raman (300–3 500 cm^–1) spectra are reported for metal(II) halide pyridine complexes of the following stoicheiometries: [MX₂(py)₂](M = Mn, Fe, Co, Ni, Cu, Zn, Cd, or Hg); [MX₂(py)₄](M = Fe, Co, or Ni); [MX₂(py)₂](M = Co, Cu, Cd, or Hg); and [Hg₃X₆(py)₂](X = Cl or Br). Structure–spectra correlations have been found for the dipyridine complexes whose structures are either monomeric tetrahedral {M = Zn or Co; X = Cl or Br; [HgBr₂(py)₂] and [Cdl₂(py)₂]}, polymeric octahedral (M = Mn, Ni, or Cd; X = Cl or Br; M = Fe or Co; X = Cl), or distorted polymeric octahedral {M = Cu, X = Cl or Br; and [HgCl₂(py)₂]}. For a given series of isomorphous complexes there is a correlation between the sum of the difference between the liquid and ligand values of ν₂, ν₃, ν₄, ν₅, ν₆, ν₇, ν₈, ν₉, ν₁₀, ν₁₇, ν₂₇, and (ν₉+ν₁₀) and the strength of the metal–nitrogen bond as measuredbythe ν(M–N) value.