Structure and fluxional behavior of platinum and palladium complexes having MSi or MSn (M=Pt or Pd) inter-element linkages

Hexamethyldistannane reacts with Pt{P(MeC6H4)3}4 at −30°C to afford the oxidative addition product: cis-[Pt(SnMe3)2{P(MeC6H4)3}2]. The structure is distinctly distorted from planarity: the dihedral angle between the PPtP and the SnPtSn planes is 34.6°. The solution 31P-NMR spectra indicate that the complex shows reversible fluxional behavior. The fluxional process is attributed to the intramolecular twist-rotational motion via pseudo tetrahedral transition state. A similar fluxional process is observed with bis(silyl)bis(phosphine)platinum and bis(stannyl)bis(phosphine)palladium complexes.