XAFS study on the structure of ytterbium(III) trifluoromethanesulfonates as a new type catalyst

Yb L-3-edge XAFS spectroscopy was applied to study on the local structures around Yb atoms in ytterbium(III) trifluoromethanesulfonates (Yb(OTf)(3)) c atalysts dissolved in various solution and those in Yb(OTtf)(3) chiral cata lysts prepared by a choice of two types of achiral ligands. XAFS analyses s howed the difference in the coordination number of oxygen atoms between Yb( OTf)(3) catalysts dissolved in aqueous and nonaqueous solutions, suggesting the activation of the Yb(OTf)(3) catalyst by the hydration. For the two Yb (OTf)(3) chiral catalysts, both the catalysts were found to be present as t rivalent ytterbium oligomer. Curve-fitting analysis of EXAFS showed that th e Yb-Yb distance of two catalyst complexes is fairly different from each ot her, i.e., one is 3.68 Angstrom and the other 4.04 Angstrom which is expect ed to explain the difference of the catalytic performance of the two chiral catalysts.