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

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 H 2 O EXAFS experiments yield an average Y 3+ -O distance of 2.33+or-0.02 AA for the YBr 3 and 2.34+or-0.02 AA for the YCl 3 . Investigations by means of Raman spectroscopy with substitution of the solvent by D 2 O for a 2.1M solution of YCl 3 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.