A VIBRATIONAL SPECTROSCOPIC STUDY OF HOFMANN-TYPE COMPLEXES OF 3-METHYLPYRIDINES AND 4-METHYLPYRIDINES

The FT-IR and Raman spectra of eight new Hofmann-type complexes of 3- and 4-methylpyridine, ML(2)Ni(CN)(4) (M = Mn, Fe, Co or Zn; L = 3- or 4-methylpyridine) are reported. The structure consists of corrugated p olymeric layers of [M-Ni(CN)(4)](infinity) with methylpyridine molecul es bound directly to the metal (M). For a given ligand (3-Mepy or 4-Me py) the effects of metal-ligand bond formation on the ligand modes are examined and the metal sensitivity sequence of the ligand frequencies is found to be Mn < Fe < Co < Zn. The metal-ligand bond strengths of the methyl derivatives of pyridine in which the substituents are in di fferent positions have also been compared and are found to increase in the order 3-Mepy < 4-Mepy for a given transition metal. The effective magnetic moments of the complexes are given.