VIBRATIONAL SPECTRA OF THE HEXAHALOMETALATE COMPLEXES OF THE PLATINUM METALS

Abstract

The Raman and infrared spectra of alkali salts of octahedral iridium hexahalide complexes and osmium hexahalide complexes have been measured at room temperature. Lattice vibrations and stretching and bending frequencies of the metal-halogen bonds were observed and interpreted. Force constant calculations were used to obtain values for unobservable fundamental modes, and to compare bond strengths among various 5d hexahalometalate ions. Certain dramatic differences in the relative intensities of $v_{1}$ and $v_{2}$ in $IrCl_{n}^{2-}$, $IrBr_{6}^{2-}$, $IrI_{6}^{-2}$, $OsCl_{6}^{2-}$, and $OsBr_{6}^{2-}$ indicate that the supposed occurrence of dynamic Jahn-Teller effects may in some cases be quenched by spin-orbit interaction and/or charge transfer.