A VIBRATIONAL SPECTROSCOPIC STUDY OF TRANSITION-METAL TETRACYANONICKELATE COMPLEXES OF 2-CHLOROPYRIDINE AND 2-BROMOPYRIDINE

The FT-IR and Raman spectra of eight new complexes of formula ML2Ni(CN )(4) (where M = Mn, Fe, Co, Ni, Cu or Cd and L = 2-chloropyridine; M = Ni or Cd and L = 2-bromopyridine) are reported. The spectroscopic res ults indicate that the complexes have structures consisting of corruga ted polymeric layers of [M-Ni(CN)(4)](infinity) with 2-substituted pyr idine molecules bound directly to the metal (M). For a given ligand (2 -Clpy or 2-Brpy) the effects of metal-ligand bond formation on the lig and modes are examined. Metal-ligand bond strengths of the halo-deriva tives of pyridine (L = 2-Clpy or 2-Brpy), inferred by the effects on f requency shifts of certain ligand modes, have also been compared.