PALLADIUM(0) COMPLEXES COORDINATED WITH SUBSTITUTED OLEFINS AND TERTIARY PHOSPHINE-LIGANDS

New palladium(0) complexes with a variety of coordinated olefins [Pd(olefin)(PMePh2)2] (II) (olefin = styrene, ethyl methacrylate, methyl methacrylate, methyl acrylate, methacrylonitrile, and dimethyl maleate), were prepared by the reactions of [PdEt2(PMePh2)2] (I) with corresponding olefins in toluene. These complexes were characterized by means of elemental analysis, IR and 1H NMR spectroscopy and the chemical reactions. The dissociation of the coordinated olefin from complex II in solution was confirmed by spectroscopic studies of [Pd(mma)(PMePh2)2] (mma = methyl methacrylate). From the variable temperature NMR study, kinetic parameters for the dissociation process were determined as Ea = 7 kcal/mol, and ΔS‡ (293 K) = -30 cal/deg · mol. Some new hydrido complexes, [Pd(H)ClL2] (IV) (L = PMePh2, PEtPh2 and PEt2Ph), were prepared by the reactions of [Pd(olefin)L2] with dry HCl. © 1979.