Phosphine, methyl complexes with

Complexes of the type (L)AuR have been isolated with a large variety of donors L, including predominantly tertiary phosphines and isocyanides. The dinuclear complex (dppm)(AuMe)2 has been prepared by treatment of (dppm)(AuCl)2 with MeLi and structurally characterized.17 Examples (L)AuR with a carbene ligand L are also known. A simple methyl compound was prepared from the chloride complex with dimethylmagnesium (Equation (l)).18... 

Pd bond in Me2Pd(dmpe) [dmpe=l,2-bis(dimethylphosphino)ethane] to generate phosphinate-palladium species with extrusion of a methane molecule (Scheme 40). Upon treatment the resulting palladium species with diphenylphosphine oxides, the remaining methyl-palladium bond was pro-tonated and a phosphinyl(phosphinato)palladium complex (20) was isolated. 

Reaction rates have first-order dependence on both metal and iodide concentrations. The rates increase linearly with increased iodide concentrations up to approximately an I/Pd ratio of 6 where they slope off. The reaction rate is also fractionally dependent on CO and hydrogen partial pressures. The oxidative addition of the alkyl iodide to the reduced metal complex is still likely to be the rate determining step (equation 8). Oxidative addition was also indicated as rate determining by studies of the similar reactions, methyl acetate carbonylation (13) and methanol carbonylation (14). The greater ease of oxidative addition for iodides contributes to the preference of their use rather than other halides. Also, a ratio of phosphorous promoter to palladium of 10 1 was found to provide maximal rates. No doubt, a complex equilibrium occurs with formation of the appropriate catalytic complex with possible coordination of phosphine, CO, iodide, and hydrogen. Such a pre-equilibrium would explain fractional rate dependencies. 

Aqueous biphasic catalysis is also used in homogeneous hydrogenations.117-119 In new examples Ru clusters with the widely used TPPTN [tris(3-sulfonatophenyl) phosphine] ligand120 and Rh complexes with novel carboxylated phosphines121 were applied in alkene hydrogenation, whereas Ru catalysts were used in the hydro-genation of aromatics. Aerobic oxidation of terminal alkenes to methyl ketones was carried out in a biphasic liquid-liquid system by stable, recyclable, water-soluble Pd(II) complexes with sulfonated bidentate diamine ligands.124... 

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