Electronic, resonance Raman and force constant studies of mixed-valence linear-chain complexes of platinum and palladium

Abstract

The electronic, Raman and resonance Raman spectra of a series of mixed-valence, halogen-bridged, linear-chain complexes of platinum and palladium have been recorded. Long progressions in the v 1(X-M-X) symmetric chain-stretching mode (M = Pt or Pd, X = Cl, Br or I) are observed under resonance conditions. Mixed metal, linear chain species e.g. of the type ⋯ X-Pt IV-X ⋯ Pd II ⋯ X-Pt IV-X ⋯ have also been prepared and studied similarly. The axial stretching vibrations of these complexes are shown to be satisfactorily described by a normal coordinate treatment based on a simple linear-chain model. The M IV-X force constants (2.1-0.9 mdyn Å −1 ) are ca. 15% less than those of the corresponding X-Pt IV-X monomers.