Synthesis of the Complex Catalysts Modeling a Reductive Elimination Reaction and Their Functions

1.通过[Pd_2（mu-Cl）_2（pi-allyl）_2]或[PtCl（allyl）]_4与叔膦的桥裂反应，以及与LiMe的甲基化反应，以高产率合成了[（pi-allyl）M（Me）（PR_3）]（M= Pd或Pt）.通过IR、MS和NMR（~ 1H，~ 1C）对所得配合物进行了表征<13>.配合物的热稳定性在固态和溶液中进行。气相色谱分析显示，在钯配合物中的主要有机产物是乙烷，而不是1-丁烯。这一结果是由分子间的还原消除乙烷从甲基桥接的π-烯丙基钯双核配合物，形成的膦配体的解离。另一方面，铂配合物分解时不放出乙烷，只放出丙烯和甲烷.还考察了膦和烯烃对热稳定组分的加和效应。在钯催化剂中，膦和马来酸酐的加入分别导致了50%和90%的1-丁烯的生成，而在铂催化剂中，膦的加成作用不明显，只有马来酸酐的加入促进了偶联反应.铂络合物在阳极峰电位（1.22 V vs. Ag/AgCl）下的控制电位电解揭示了以50%摩尔比的1-丁烯的演化。这种偶联促进作用与在该化合物中加入π-酸的作用相当，并提出了一种涉及阳离子中间体[（π-烯丙基）Pt（Me）（PR_3）]^+的机理来解释这种作用。在π-烯丙基铂配合物的溶液中加入双膦，分离出稳定的σ-烯丙基配合物，但它们的配合物的theimolysis显示没有偶联反应发生，只有丙烯和甲烷的演变。

1. Bridge-splitting reactions of [Pd_2(mu-Cl)_2(pi-allyl)_2] or [PtCl(allyl)]_4 with tertiary phosphines, followed by methylations with LiMe afforded the desired complexes [(pi-allyl)M(Me)(PR_3)] (M= Pd or Pt) in high yields.2. The complexes thus obtained were characterized by IR, MS, and NMR (^1H, ^<13>C) spectroscopy.3. Thermolysis of the complexes was carried out in the solid state and in solution. Gas-chromatographic analysis of the evolved gases was revealed that in palladium complexes the major organic product is ethane rather than 1-butene. This result was accounted for by the intermolecular reductive-elimination of ethane from the methyl-bridged pi-allylpalladium dinuclear complex, formed by dissociation of the phosphine ligand. On the other hand, the platinum complexes decompose with no evolution of ethane and with the evolution of propene and methand, exclusively.4. Additive effects of phosphine and alkene on the thermolysis components were also examined. In the palladium case, the addition of phosphine and maleic anhydride resulted in the evolution of 1-butene in a 50% and a 90% relative ratios, respectively, while in the platinum case the additive effect of phosphine was not recognized and the coupling reaction was promoted only in the addition of maleic anhydride.5. The controlled-potential electrolysis of the platinum complex at the anodic peak potential (1.22 V vs. Ag/AgCl) revealed the evolution of 1-butene in a 50% molar ratio. This coupling-promoting effect is comparable to that of the addition of pi-acid in the thermolysis, and a mechanism involving the cationic intermediate [(pi-allyl)Pt(Me)(PR_3)]^+ was proposed to explain the effect.6. On the addition of diphosphines in the solutions of pi-allylplatinum complexes, stable sigma-allyl complexes were isolated, but theimolysis of their complexes revealed that no coupling reaction occurs on it; only propene and methane evolved.