Ab initio X-ray absorption spectroscopy study of the solvation structure of yttrium (III) in dimethyl sulfoxide.

ABSTRACT

The solvation structure of yttrium (III) in dimethyl sulfoxide has been determined by studying both the extended X-ray absorption fine structure (EXAFS) and the X-ray absorption near edge structure (XANES) regions of the Y K-edge absorption spectra. Although the EXAFS technique provides accurate information about the next neighbors coordination distances, no unambiguous determination of the coordination polyhedron is obtained. This failure is counteracted by the study of the near-edge part of the absorption spectrum (XANES) because of its high sensitivity to the bonding geometry. We have performed an extensive and systematic ab initio computation of the Y K-edge XANES spectrum of yttrium (III) in dimethyl sulfoxide within the multiple-scattering framework. The comparison between the experimental data and the theoretical calculations has demonstrated that the solvation sphere of the yttrium cation is best modeled by eight dimethyl sulfoxide molecules each oriented to give an Y-O-S angle close to 130 degrees .