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.