Research on the reaction course of metal-carbon bond formation

1.[M(HFAc)_2](M=铂，Pd)与[18-冠-6/K](X=Cl，Br，I，NO_2，NO_3NCO等)反应。或[Ph_4P]X(X=Cl，Br，I)在CH2Cl2中生成各种产物。反应顺序如下：5-配位络合物[MX(HFAC)_2]^-、[MX(HFAC)(HFAC-O)]^-、[MX_2(HFAC)]^-和[MX_4]^&lt；2-或[M_2(Mu-X)_2X_4]^&lt；-2&gt；当X的碱性较弱时，生成含有M-C键的[MX(HFAC)(HFAC-C^3)]^-。在M-C键形成的过渡态，HfAc~(2-)离子对[MX_2(HfAc)]~(-)中的金属原子进行静电和位阻不利的攻击。[Ph_4P][MX(HFAc)_2](X=Cl，Br，I)为红色晶体。通过单晶X射线分析，确定了在基面上含有卤化物配体的扭曲的四方锥体结构。变温核磁共振谱可用溶液中两个独立的动态运动来解释：顶端O和X-顺式O之间的位置交换(路径A)和顶端O和X-反式O之间的位置交换(路径B)。每条路径的交换率的比率取决于卤化物的种类；k_A&gt；k_B(Cl)、k_B&gt；&gt；k_A(bR，i)。K_A的顺序为Cl&gt；I，但k_B的顺序为I&gt；BR&gt；Cl。顺反异构化速率的预测顺序为：Cl&gt；br&gt；I。[Pd(HFAc)_2]与单肟反应生成了一个新的Pd(II)配合物，其中一个HFAC-O，O‘和一个HFAC-C，N-螯合物，其中C^3键的HFAC与N键的单肟之间形成了一个C-O键。其结构经X-射线分析和核磁共振波谱确证。在低温下，核磁共振检测到一种前体化合物[Pd(HFAc)(Oxime)_2](HFAC)。首次由[Pt(Acac)_2]与PPh_3在甲醇中反应合成了第一个acac(3-)与铂(II)的配合物。多核核磁共振谱揭示了ETA^3：C，O-键结构。M-C键的形成遵循“离子反应机制”，因为外层球面上的acac~-阴离子从acac(2-)配体上提取甲基质子似乎是关键步骤。

1. [M(hfac)_2] (M=Pt, Pd) reacted with [18-crown-6/K] (X=Cl, Br, I,No_2, NO_3 NCO etc.) or [Ph_4P] X (X=Cl, Br, I) in CH_2Cl_2 to give a variety of products. The reaction proceeds successively as follows, 5-coordinate complex [MX(hfac)_2]^-, [MX(hfac)(hfac-O)]^-, [MX_2(hfac)]^-, and[MX_4]^<2-> or [M_2(mu-X)_2X_4]^<-2>. When a basicity of X is weak, [MX(hfac)(hfac-C^3)]^-, containing M-C bond, was produced. In the transition state of the M-C bond formation, hfac^- ion should attack the metal atom in [MX_2(hfac)]^- ; electrostatically and sterically unfavorable path. [Ph_4P][MX(hfac)_2] (X=Cl, Br, I) was isolated as red crystals. A distorted square pyramidal structure with halide ligand in the basal plane was determined by single crystal X-ray analysis. The temperature-variable NMR spectra were explained by two independent dynamic motions in solution ; a site exchange between apical-O and X-cis-O (Path A), and a site exchange between apical-O and X-trans-O (Path B). A ratio of the exchange rates of each path is dependent on the kind of the halide ; k_A>k_B (Cl), k_B>>k_A (Br, I). k_A is in the order, Cl>I,but k_B is in the reverse order, I>Br>Cl. The rate of the cis-trans isomerization is predicted as in the order, Cl>Br>I.2. Reaction of [Pd(hfac)_2] with monoximes gave new Pd(II) complex with one hfac-O,O' and one hfac-oxime-C,N-chelate, in which a C-O bond was formed between the C^3-bonded hfac and the N-bonded monoxime. The structure was determined by an X-ray analyzes and NMR spectra. A precursor complex, [Pd(hfac)(oxime)_2](hfac), was detected by NMR at low termperature.3. First acac (3-) complex with Pt(II) was prepared by the reaction of [Pt(acac)_2] and PPh_3 in MeOH.Multi-nuclear NMR spectra revealed the eta^3 : C,O-binding structure. M-C bond formation was deduced to follow "ionic reaction mechanism, ", since a methyl proton abstraction by an acac^- anion in the outer sphere from acac (2-) ligand seems to be a key step.