Research on the reaction course of metal-carbon bond formation

1. [M(hfac)_2] （M=Pt, Pd）与[18-crown-6/K] （X=Cl, Br， I,No_2， NO_3 NCO等）或[Ph_4P] X （X=Cl, Br， I）在CH_2Cl_2中反应得到多种产物。反应顺序为：五坐标配合物[MX(hfac)_2]^-、[MX(hfac)(hfac- o)]^-、[MX_2(hfac)]^-、[MX_4]^<2->或[M_2(mu-X)_2X_4]^<-2>。当X的碱性较弱时，生成含有M-C键的[MX(hfac)(hfac- ^3)]^-。在M-C键形成的过渡态，hfac^-离子应攻击[MX_2(hfac)]^-中的金属原子；静电和空间阻力路径。[Ph_4P][MX(hfac)_2] （X=Cl, Br， I）分离得到红色晶体。通过单晶x射线分析，确定了基面上有卤化物配体的畸变方锥体结构。温度变化的核磁共振谱用溶液中两个独立的动态运动来解释；一个顶点o和x -顺- o之间的位点交换（路径a），一个顶点o和x -反- o之间的位点交换（路径B）。每条路径的汇率比率取决于卤化物的种类；k_A>k_B (Cl) k_B>>k_A (Br， I) k_A的顺序是Cl b> I，而k_B的顺序相反，I>Br>Cl。顺反异构化速率的预测顺序为Cl>Br>I.2。[Pd(hfac)_2]与单肟反应生成新的Pd（II）配合物，该配合物具有一个hfac-O，O'和一个hfac-肟-C， n -螯合物，在C^3键的hfac与n -键的单肟之间形成一个C-O键。通过x射线分析和核磁共振光谱确定了其结构。2 .用核磁共振（NMR）在低温下检测到前驱物[Pd(hfac)（肟）_2]（hfac）。用[Pt(acac)_2]和PPh_3在MeOH中反应制备了第一个acac（3-）与Pt（II）配合物。多核磁共振谱显示了eta^3: C， o结合结构。M-C键的形成被推断为遵循“离子反应机制”，因为外球中acac^-阴离子从acac（2-）配体中提取甲基质子似乎是一个关键步骤。

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.