Apparent Fluxionality in Diethyl(triethylphosphine)platinum(II), a Coordinatively Unsaturated Intermediate in β-Hydride Elimination

The thermal decomposition of (Et₃P)₂Pt(C₂H₅)₂ proceeds by rate-limiting dissociation of triethylphosphine, followed by β-hydride elimination from a PtC₂H₅ group (Scheme I, 2 →• 3). Isotopic labeling and kinetics indicate that the two platinum-bound ethyl groups of the coordinatively unsaturated intermediate diethyl(triethylphosphine)platinum(II) lose hydrogen with approximately equal probability (Scheme I). Thus, either side-to-side motion of the triethylphosphine ligand within a "T"-shaped complex (2a ⇆ 2b, Scheme I) is fast relative to reductive elimination of ethane from 3 or some other process or geometry renders the ethyl groups roughly equivalent on this time scale.