The structure of the first coordination shell of the yttrium ion in concentrated aqueous solutions of YBr₃and YCl₃

Abstract

Yttrium hydrates with eight-coordinated water molecules seem to be the predominant species in concentrated aqueous solutions of yttrium bromide and chloride. For molarities from approximately 2.1 down to 0.6M in H2O EXAFS experiments yield an average Y3+-O distance of 2.33+or-0.02 AA for the YBr3 and 2.34+or-0.02 AA for the YCl3. Investigations by means of Raman spectroscopy with substitution of the solvent by D2O for a 2.1M solution of YCl3 lead to an isotopic shift of 1.052+or-0.007 for the polarized band assigned to the stretching vibrational mode of the complex, which corroborates the idea of the presence of a (relatively) stable hydrate of the yttrium ion.