Synthesis of the complexes [PdClR(cod)] (R = benzyl, ethyl; cod = 1,5-cyolooctadiene). β-Elimination from [PdClEt(cod)] to give the η1,η2, and η3 isomers of [Pd2(μ-Cl)2(C8H13)2]

Article abstract of DOI:10.1139/v96-226

Treatment of [PdCl₂(cod)] with tetrabenzyltin gives the benzylpalladium complex [PdCl(CH₂Ph)(cod)] (cod = 1,5-cyclooctadiene), 1a, whose structure has been determined by X-ray crystallography. It adopts approximate square-planar geometry, with the double bonds perpendicular to the square plane. The corresponding ethylpalladium derivative 1b has been prepared by a similar method, but it is considerably less stable. It decomposes by β-elimination to produce ethene and a transient hydride complex, which either undergoes migratory insertion to give [Pd₂(μ-Cl)₂(η¹,η²-C ₈H₁₃)₂], 2a, or dinuclear reductive elimination with a second molecule of 1b to produce ethane, [PdCl₂(cod)], free cyclooctadiene, and palladium metal. Complex 2a has also been prepared by reaction of [PdCl₂(cod)] with NaBH₄. At higher temperatures 2a converts to an equilibrium mixture with its η³-allyl isomer, 2b. Reactions of [PdCl₂(cod)] or K₂PdCl₄ in the presence of cyclooctadiene in aqueous solution to produce 2a or 2b have also been investigated.