T. Yoshida, Tsunehiro Tanaka, Takashi Yamamoto
Jun 1, 1999
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Journal
Japanese Journal of Applied Physics
Abstract
Yb L3-edge XAFS spectroscopy was applied to study on the local structures around Yb atoms in ytterbium(III) trifluoromethanesulfonates (Yb(OTf)3) catalysts dissolved in various solution and those in Yb(OTf)3 chiral catalysts prepared by a choice of two types of achiral ligands. XAFS analyses showed 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 trivalent ytterbium oligomer. Curve-fitting analysis of EXAFS showed that the Yb-Yb distance of two catalyst complexes is fairly different from each other, i.e., one is 3.68 Å and the other 4.04 Å, which is expected to explain the difference of the catalytic performance of the two chiral catalysts.