The phosphinoethylsilyl group as a bifunctional chelate. Asymmetric induction at platinum(II)

Abstract

The synthesis of cis-[Pt(PPh₂CH₂CH₂SiR¹R²)₂] is reported, and its geometry, inferred from ³¹P n.m.r. data, is confirmed by X-ray crystallography for R¹= R²= Me; when R¹≠ R² racemic and meso-diastereomers are formed in varying ratio consistent with asymmetric induction during stepwise chelation to give the rac-complex as the preferred isomer, and this is proven where R¹= Me, R²= Ph by diastereomer separation followed by Pt–Si bond-cleavage with (+)-EtCH(Me)-CH₂I.