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

The triple ligand transfer reaction between planar-chiral cyclopentadienyl–ruthenium complexes [Cp′Ru(NCMe)3][PF6] (1) (Cp′ = 1-(COOR2)-2-Me-4-R1C5H2; R1 = 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 View the MathML sourceSCp∗RRu∗ 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′Ru{P(OMe)3}(NCMe)2][PF6] (7) and CpFe(CO)2X (8) produced Cp′Ru{P(OMe)3}(CO)X (9), the selectivity at the ruthenium center was low.