Diastereoselectivity at chiral metal center of half-sandwich-type ruthenium complexes with planar-chiral cyclopentadienyl ligands in multiple ligand transfer reaction

摘要

The triple ligand transfer reaction between planar-chiral cyclopentadienyl-ruthenium complexes [Cp'Ru(NCMe)(3)][PF6] (1) (Cp' = 1-(COOR2)-2-Me-4-(RC5H2)-C-1; R-1 = Me, Ph, t-Bu) and iron complexes CpFe(CO)(L)X (2) (L = PMe3, PMe2Ph, PMePh2, PPh3; X = I, Br) resulted in the formation of metal-centered chiral ruthenium complexes Cp'Ru(CO)(L)X (3) in moderate yields with diastereoselectivities of up to 68% de. The configurations of some major diastereomers were determined to be S PR,, by X-ray crystallography. The diastereoselectivity of 3 was under kinetic control and not affected by the steric effect of the substituents on the Cp' ring of 1 and the phosphine of 2. Although the double ligand transfer reaction between [Cp'Au{P(OMe)(3)}(NCMe)(2)][PF6] (7) and CpFe(CO)(2)X (8) produced Cp'Ru{P(OMe)(3)}(CO)X (9), the selectivity at the ruthenium center was low. (c) 2005 Elsevier B.V. All rights reserved.