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.