Crystal structure of chiral binaphthol lanthanide complexes and their catalysis in asymmetric transfer hydrogenation of acetophenone

Abstract

Heterometallic [(THF)2Na]3[Ln(R-Binolate)3(H2O)] [Ln = Sm (1) and Gd (2)] has been synthesized by the reactions of either LnCl3 or LnBr3 with 3 equiv. Na(R-HBinolate) and characterized by X-ray crystallographic analysis. Structural analyses proposed that 1 and 2 are isomorphous complexes, crystallizing in the hexagonal space group P63 with C3 symmetry. The coordination geometry of the lanthanide ions in 1 and 2 can be best approximated as a mono-capped triangle antiprism. When complexes 1 and 2 were employed as catalysts in the Meerwein–Ponndorf–Verley (MPV) reactions of acetophenone, the S-phenylethanol was separated in 94 and 85% enantiomeric excess (e.e.) for 1 and 2, respectively. Copyright © 2005 John Wiley & Sons, Ltd.