Raman spectra of concentrated solutions of magnesium and aluminium chloride in water and deuterium oxide

Abstract

The Raman spectra of concentrated aqueous solutions of AlCl₃ and MgCl₂ in H₂O and D₂O have been obtained and the shapes of the Raman bands attributed to oscillations of the cation hydrates more accurately determined than in previous reports. Isotopic shifts have been interpreted using a model in which the Al³⁺ or Mg²⁺ cations are octahedrally coordinated by six water molecules and slightly perturbed by two neighbouring anions. Electrostatic interactions between ions and coordinated water molecules and between water molecules themselves were estimated. Preliminary results are also presented for aqueous solutions of BeCl₂.