| 1244030-78-1

• CAS: 1244030-78-1
• 化学式: C₄₂H₆₇Ce
• 分子量: 712.114
• InChiKey: RGRVMVGHUKZLEI-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  None
• 重原子数：
  None
• 可旋转键数：
  None
• 环数：
  None
• sp3杂化的碳原子比例：
  None
• 拓扑面积：
  None
• 氢给体数：
  None
• 氢受体数：
  None

反应信息

• 作为反应物：
  描述：

  以 全氘代环己烷 为溶剂， 生成 [(1,2,4-tri-tert-butylcyclopentadienyl)(1,2,4-tri-tert-butylcyclopentadienyl(-H))Ce]
  参考文献：
  名称：

  The reaction of bis(1,2,4-tri-t-butylcyclopentadienyl)ceriumbenzyl, Cp′2CeCH2Ph, with methylhalides: a metathesis reaction that does not proceed by a metathesis transition state

  摘要：

  [1,2,4-(Me3C)3C5H2]2CeCH2Ph 和 CH3X（X = F、Cl、Br 和 I）之间的实验反应产生了元交换产物 [1,2,4-(Me3C)3C5H2]2CeX 和 CH3CH2Ph。苄基衍生物和金属环 [1,2,4-(Me3C)3C5H2][(Me3C)2C5H2C(CH3)2CH2]Ce 以及甲苯之间的平衡使反应变得复杂，因为金属环会与 CH3X 发生反应。标记研究表明，甲基卤化物的甲基完整地转移到了苄基上。通过对 (C5H5)2CeCH2Ph 和 CH3F 的 DFT 计算发现，该机理不是通过四中心机理（Ï-键元合成）进行的，而是通过涉及 Cp2Ce 片段的触变转移的较低障碍过程进行的，因此在过渡态，苯环的对位碳附着在 Cp2Ce 片段上，而苄基的 CH2 片段攻击因与金属离子配位而活化的 CH3F。因此，该机制被归类为关联交换过程。

  DOI：

  10.1039/b918103b
• 作为产物：
  描述：

  bis(1,2,4-tri-tert-butylcyclopentadienyl)cerium benzyl 、 对二甲苯 以 neat (no solvent) 为溶剂， 生成
  参考文献：
  名称：

  The reaction of bis(1,2,4-tri-t-butylcyclopentadienyl)ceriumbenzyl, Cp′2CeCH2Ph, with methylhalides: a metathesis reaction that does not proceed by a metathesis transition state

  摘要：

  [1,2,4-(Me3C)3C5H2]2CeCH2Ph 和 CH3X（X = F、Cl、Br 和 I）之间的实验反应产生了元交换产物 [1,2,4-(Me3C)3C5H2]2CeX 和 CH3CH2Ph。苄基衍生物和金属环 [1,2,4-(Me3C)3C5H2][(Me3C)2C5H2C(CH3)2CH2]Ce 以及甲苯之间的平衡使反应变得复杂，因为金属环会与 CH3X 发生反应。标记研究表明，甲基卤化物的甲基完整地转移到了苄基上。通过对 (C5H5)2CeCH2Ph 和 CH3F 的 DFT 计算发现，该机理不是通过四中心机理（Ï-键元合成）进行的，而是通过涉及 Cp2Ce 片段的触变转移的较低障碍过程进行的，因此在过渡态，苯环的对位碳附着在 Cp2Ce 片段上，而苄基的 CH2 片段攻击因与金属离子配位而活化的 CH3F。因此，该机制被归类为关联交换过程。

  DOI：

  10.1039/b918103b

文献信息

• Two [1,2,4-(Me₃C)₃C₅H₂]₂CeH Molecules are Involved in Hydrogenation of Pyridine to Piperidine as Shown by Experiments and Computations
  作者：Lionel Perrin、Evan L. Werkema、Odile Eisenstein、Richard A. Andersen

  DOI：10.1021/ic500133y

  日期：2014.7.7

  Hydrogenation of pyridine to piperidine catalyzed by [1,2,4-(Me3C)(3)C5H2](2)CeH, abbreviated as Cp'2CeH or [Ce]'-H, is reported. The reaction proceeds from Cp'Ce-2(2-pyridyl), isolated from the reaction of pyridine with Cp(')2CeH, to Cp'Ce-2(4,5,6-trihydropyridyl), and then to Cp'Ce-2(piperidyl). The cycle is completed by the addition of pyridine, which generates Cp'Ce-2(2-pyridyl) and piperidine. The net reaction depends on the partial pressure of H-2 and temperature. The dependence of the rate on the H-2 pressure is associated with the formation of Cp'2CeH, which increases the rate of the first and/or second additions of H-2 but does not influence the rate of the third addition. Density functional theory calculations of several possible pathways are consistent with three steps, each of which are composed of two elementary reactions, (i) heterolytic activation of H-2 with a reasonably high energy,Delta G double dagger = 20.5 kcal mol(-1), on Cp'Ce-2(2-pyridyl), leading to Cp'2CeH(6-hydropyridyl), followed by an intramolecular hydride transfer with a lower activation energy, (ii) intermolecular addition of Cp'2CeH to the C-4=C-5 bond, followed by hydrogenolysis, giving Cp'Ce-2(4,5,6-trihydropyridyl) and regenerating Cp'2CeH, and (iii) a similar hydrogenation/hydrogenolysis sequence, yielding Cp'Ce-2(piperidyl). The calculations reveal that step ii can only occur in the presence of Cp'2CeH and that alternative intramolecular steps have considerably higher activation energies. The key point that emerges from these experimental and computational studies is that step ii involves two Cp'Ce-2 fragments, one to bind the 6-hydropyridyl ligand and the other to add to the C-4=C-6 double bond. In the presence of 112, this second step is intermolecular and catalytic. The cycle is completed by reaction with pyridine to yield Cp'Ce-2(2-pyridyl) and piperidine. The structures of Cp'2CeX, where X = 2-pyridyl, 4,5,6-trihydropyridyl, and piperidyl, are fluxional, as shown by variable-temperature H-1 NMR spectroscopy.