bis((1,2,4-tri-tert-butyl-d27)cyclopentadienyl)cerium fluoride | 856660-26-9

• 英文名称: bis((1,2,4-tri-tert-butyl-d27)cyclopentadienyl)cerium fluoride
• CAS: 856660-26-9
• 化学式: C₃₄H₅₈CeF
• 分子量: 679.524
• InChiKey: FCWXJOUJKSXPCY-HTAJBYLJSA-M

计算性质

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

• 作为产物：
  描述：

  氟甲烷 、 以 全氘代环己烷 为溶剂， 生成 bis((1,2,4-tri-tert-butyl-d27)cyclopentadienyl)cerium fluoride
  参考文献：
  名称：

  Hydrogen for Fluorine Exchange in CH_4-xF_x by Monomeric [1,2,4-(Me₃C)₃C₅H₂]₂CeH:  Experimental and Computational Studies

  摘要：

  The monomeric metallocenecerium hydride, CP'(CeH (Cp' = 1,2,4-tri-tert-butylcyclopentadienyl), reacts instantaneously with CH)(F, but slower with CH)(F)(, to give CP')(CeF and CH)(2)(3)(2)(2)(2)(4) (in each case, a net H for F exchange reaction. The hydride reacts very slowly with CHF)(, and not at all with CF)(, to give CP'2CeF, H)(, and 1,2,4- and 1,3,5-tri-tert-butylbenzene. The substituted benzenes are postulated to result from trapping of a fluorocarbene fragment derived by a-fluoride abstraction from Cp')(CeCF)(. The fluoroalkyl, Cp')(CeCF)(, is generated by reaction of CP')(CeH and Me)(SiCF)(3)(4)(2)(2)(3)(2)(3)(2)(3)(3) (or by reaction of the metallacycle, [(Cp')(Me)(C))(C)(H)(C(Me)()CH)(]Ce, with CHF)(, and its existence is inferred from the products of decomposition, which are Cp)(CeF, the isomeric tri-tert-butylbenzenes and in the case of Me)(SiCF)(, Me)(SiH. The fluoroalkyls, CP')(CeCH)(F and CP')(CeCHF)(, generated from the metallacycle and CH)(F and CH)(F)(, respectively, are also inferred by their decomposition products, which are CP')(CeF, CH)(, and CHF, respectively, which are trapped. DFT(B3PW91) calculations have been carried out to examine several reaction paths that involve CH and CF bond activation. The calculations show that the CH activation by CP)(CeH proceeds with a low barrier. The carbene ejection and trapping by H)(3)(2)(5)(2)(2)(2)(3)(2)(3)(3)(3)(2)(2)(2)(2)(3)(2)(2)(2)(2)(2)(2) (is the rate-determining step, and the barrier parallels that found for reaction of H)(2) (with CH)(, CHF, and CF)(2)(2). The barrier of the rate-determining step is raised as the number of fluorines increases, while that of the CH activation path is lowered as the number of fluorines increases, which parallels the acidity.

  DOI：

  10.1021/ja0504800

文献信息

• 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
  作者：Evan L. Werkema、Richard A. Andersen、Laurent Maron、Odile Eisenstein

  DOI：10.1039/b918103b

  日期：——

  The experimental reaction between [1,2,4-(Me3C)3C5H2]2CeCH2Ph and CH3X, X = F, Cl, Br, and I, yields the metathetical exchange products, [1,2,4-(Me3C)3C5H2]2CeX and CH3CH2Ph. The reaction is complicated by the equilibrium between the benzyl derivative and the metallacycle [1,2,4-(Me3C)3C5H2][(Me3C)2C5H2C(CH3)2CH2]Ce, plus toluene since the metallacycle reacts with CH3X. Labelling studies show that the methyl group of the methylhalide is transferred intact to the benzyl group. The mechanism, as revealed by DFT calculations on (C5H5)2CeCH2Ph and CH3F, does not proceed by way of a four-center mechanism, a σ-bond metathesis, but by a lower barrier process involving a haptotropic shift of the Cp2Ce fragment so that at the transition state the para-carbon of the benzene ring is attached to the Cp2Ce fragment while the CH2 fragment of the benzyl group attacks CH3F that is activated by coordination to the metal ion. As a result the mechanism is classified as an associative interchange process.

  [1,2,4-(Me3C)3C5H2]2Ce Ph 和 X（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 Ph。苄基衍生物和金属环 [1,2,4-(Me3C)3C5H2][(Me3C)2C5H2C(CH3)2 ]Ce 以及甲苯之间的平衡使反应变得复杂，因为金属环会与 X 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)2Ce Ph 和 F 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 F。因此，该机制被归类为关联交换过程。