STRUCTURE AND DYNAMICS OF MOLTEN ALUMINUM AND GALLIUM TRIHALIDES .2. RAMAN-SPECTROSCOPY AND AB-INITIO CALCULATIONS

Results of Raman scattering experiments combined with ab initio molecu lar orbital calculations are presented on the structure and vibrationa l properties of molten GaI3, GaBr3, AlCl3, and AlBr3. It is confirmed that, to a high degree, all of these compounds have in the molten stat e a dimer structure, represented by M(2)X(6), consisting of two tetrah edra sharing a halide edge. It is shown that in AlCl3 the melting proc ess leads to a drastic change in the vibrational spectrum, whereas in the remaining salts the crystalline peak positions are essentially pre served.