115290-49-8Relevant academic research and scientific papers
General route to halide-bridged organopalladium A-frame complexes and studies of reductive elimination from these bimetallic systems
Stockland Jr., Robert A.,Janka, Mesfin,Hoel, Gretchen R.,Rath, Nigam P.,Anderson, Gordon K.
, p. 5212 - 5219 (2008/10/08)
Reactions of [Pd2Cl2(μ-dppm)2] with RMgX (R = Me, Et, Bu, Ph, C6H4Me-4) at low temperature, followed by addition of CBr4 and excess NH4PF6 or 1 equiv of TIPF6, provided halide-bridged organopalladium A-frame complexes of the form [Pd2R2(μ-X)(μ-dppm)2]PF6. Mixed metal complexes were obtained similarly starting from [PdCtCl2(μ-dppm)2]. Unsymmetrical A-frames of the type [Pd2(C6H2Me3-2,4,6)R(μ-Cl)(μ-d ppm)2]+ were generated reaction of [Pd(C6H2Me3-2,4,6) (dppm)2]+ (obtained by treatment of [PdCl2 (cod)] w mesitylmagnesium bromide at low temperature, followed by 2 equiv of dppm) with [Pd2R2(μ-Cl)2 (AsPh3)2]. The organopalladium A-frames did not react readily with CO, but the corresponding acyl derivatives [Pd2(COR)2(μ-Cl)(μ-dppm)2]PF6 were produced by carbonylation of [Pd2R2(μ-Cl)2(AsPh3)2] followed by addition of dppm (R = Me, Et, Bn). Thermal decomposition of [Pd2(CH2Ph)2(μ-Cl)(μ-dppm)2]Cl was found to be first order in A-frame and resulted in quantitative formation of [Pd2Cl2(μ-dppm)2] and 1,2-diphenylethane. The methyl and aryl complexes underwent both reductive elimination and hydrogen abstraction reactions. [Pd2Et2(μ-Br)(μ-ddpm)2]PF6 decomposed by β-hydride elimination and subsequent reductive elimination to yield ethene and ethane, whereas the butyl derivative gave both 1- and 2-butene. Acetic acid was formed when [Pd2(COMe)2(μ-Cl)(μ-dppm)2]PF6 was heated in dmso-d6 solution, but decarbonylation was the predominant process in dioxane. The molecular structures of [Pd2(CH2Ph)2(μ-Br)(μ-dppm)2] PF6·H2O, 2C6H6 and [Pd2Cl2(μ-Cl)(μ-dppm)2]OH· 0.5(CH3)2CO are also described.
Synthesis and Reactions of Dinuclear Palladium Complexes Containing Methyls and Hydride on Adjacent Palladium Centers: Reductive Elimination and Carbonylation Reactions
Young, S. J.,Kellenberger, B.,Reibenspies, Joseph H.,Himmel, S. E.,Manning, M.,et al.
, p. 5744 - 5753 (2007/10/02)
The transmetalation reaction of trimethylaluminum with the palladium chloride dimer Pd2Cl2(μ-dppm)2 (1) (dppm = bis(diphenylphosphino)methane) at -78 deg C gave an intermediate, Pd2ClMe(μ-dppm)2 (2), which disproportionated at ca. 10 deg C to yield the trans-face-to-face palladium dimer Pd2Cl2Me2(μ-dppm)2 (3) and a palladium dimer Pd2Cl2(μ-CH2)(μ-dppm)2 (5).The use of excess trimethylaluminum at -40 deg C gave the dimethyl complex, Pd2Me2(μ-dppm)2 (7).When 2 and 7 were protonated, a stable A-frame chloro-bridged dimer + (6) and a hydride-bidged dimer + (8) were obtained.Warming 6 in solution to ambient temperature caused the reductive elimination of methane; 8 lost methane and ethane at ambient temperatures.Both reductive eliminations were strictly intramolecular as determined by crossover experiments.The reaction of 6 with CO (1 atm) at -20 deg C first gave a carbonyl-bridged complex + (10) that rearranged to the acyl complex + (11) and then on warming eliminated acetaldehyde.The carbonylation of 8 (1 atm) proceeded stepwise to give first the mono- and then the diacyl complexes.The diacyl complex + (13) underwent the reductive elimination of acetaldehyde at ambient temperatures.
