bis(1,2,4-tri-tert-butylcyclopentadienyl)cerium hydride | 832076-19-4

• 英文名称: bis(1,2,4-tri-tert-butylcyclopentadienyl)cerium hydride
• 英文别名: bis(1,2,4-tri-tert-bytylcyclopentadienyl)cerium hydride；[(1,2,4-tri-tert-butylcyclopentadienyl)2CeH]；[(1,2,4-tri-tert-butylcyclopentadienyl)CeH]；(1,3,4-tri-tert-butylcyclopentadienyl)2CeH；[1,2,4-tri-tert-butylcyclopentadienyl]2CeH；[(1,2,4-(Me3C)3C5H2)2CeH]
• CAS: 832076-19-4
• 化学式: C₃₄H₅₉Ce
• 分子量: 607.962
• InChiKey: UIDKOERRZOHUCL-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：

  六氟苯 、 bis(1,2,4-tri-tert-butylcyclopentadienyl)cerium hydride 以 氘代苯 为溶剂， 生成 bis(1,2,4-tri-tert-butylcyclopentadienyl)cerium fluoride
  参考文献：
  名称：

  Hydrogen for Fluorine Exchange in C₆F₆ and C₆F₅H by Monomeric [1,3,4-(Me₃C)₃C₅H₂]₂CeH:  Experimental and Computational Studies

  摘要：

  The net reaction of monomeric CP'2CeH [Cp' = 1,3,4-(Me3C)(3)(C5H2)] in C6D6 with C6F6 is CP'2CeF, H-2, and tetrafluorobenzyne. The pentafluoropheny/metallocene, CP'Ce-2(C6F5), is formed as an intermediate that decomposes slowly to CP'2CeF and C6F4 (tetrafluorobenzyne), and the latter is trapped by the solvent C6D6 as a [2+4] cycloadcluct. In C6F5H, the final products are also CP'2CeF and H-2, which are formed from the intermediates CP'Ce-2(C6F5) and CP'Ce-2(2,3,5,6-C6F4H) and from an unidentified metallocene of cerium and the [2+4] cycloadducts of tetra- and trifluorobenzyne with C6D6. The hydride, fluoride, and pentafluoropheny/metallocenes are isolated and characterized by X-ray crystallography. DFT(B3PW91) calculations have been used to explore the pathways leading to the observed products of the exergonic reactions. A key step is a H/F exchange reaction which transforms C6F6 and the cerium hydride into C6F5H and CP'2CeF. This reaction starts by an eta(1)-F-C6F5 interaction, which serves as a hook. The reaction proceeds via a sigma bond metathesis where the fluorine ortho to the hook migrates toward H with a relatively low activation energy. All products observed experimentally are accommodated by pathways that involve C-F and C-H bond cleavages.

  DOI：

  10.1021/ja0451012
• 作为产物：
  描述：

  三氟甲烷 、 [(1,2,4-tri-tert-butylcyclopentadienyl)(1,2,4-tri-tert-butylcyclopentadienyl(-H))Ce] 以 全氘代环己烷 为溶剂， 生成 bis(1,2,4-tri-tert-butylcyclopentadienyl)cerium hydride
  参考文献：
  名称：

  Hydrogen for Fluorine Exchange in C₆F₆ and C₆F₅H by Monomeric [1,3,4-(Me₃C)₃C₅H₂]₂CeH:  Experimental and Computational Studies

  摘要：

  The net reaction of monomeric CP'2CeH [Cp' = 1,3,4-(Me3C)(3)(C5H2)] in C6D6 with C6F6 is CP'2CeF, H-2, and tetrafluorobenzyne. The pentafluoropheny/metallocene, CP'Ce-2(C6F5), is formed as an intermediate that decomposes slowly to CP'2CeF and C6F4 (tetrafluorobenzyne), and the latter is trapped by the solvent C6D6 as a [2+4] cycloadcluct. In C6F5H, the final products are also CP'2CeF and H-2, which are formed from the intermediates CP'Ce-2(C6F5) and CP'Ce-2(2,3,5,6-C6F4H) and from an unidentified metallocene of cerium and the [2+4] cycloadducts of tetra- and trifluorobenzyne with C6D6. The hydride, fluoride, and pentafluoropheny/metallocenes are isolated and characterized by X-ray crystallography. DFT(B3PW91) calculations have been used to explore the pathways leading to the observed products of the exergonic reactions. A key step is a H/F exchange reaction which transforms C6F6 and the cerium hydride into C6F5H and CP'2CeF. This reaction starts by an eta(1)-F-C6F5 interaction, which serves as a hook. The reaction proceeds via a sigma bond metathesis where the fluorine ortho to the hook migrates toward H with a relatively low activation energy. All products observed experimentally are accommodated by pathways that involve C-F and C-H bond cleavages.

  DOI：

  10.1021/ja0451012
• 作为试剂：
  描述：

  在 bis(1,2,4-tri-tert-butylcyclopentadienyl)cerium hydride 作用下， 以 全氘代环己烷 为溶剂， 反应 72.0h， 生成 [(1,2,4-tri-tert-butylcyclopentadienyl)(1,2,4-tri-tert-butylcyclopentadienyl(-H))Ce] 、 cerium(3+);3,4-dihydro-2H-pyridin-1-ide;2,3,5-tritert-butylcyclopenta-1,3-diene
  参考文献：
  名称：

  Two [1,2,4-(Me₃C)₃C₅H₂]₂CeH Molecules are Involved in Hydrogenation of Pyridine to Piperidine as Shown by Experiments and Computations

  摘要：

  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.

  DOI：

  10.1021/ic500133y

文献信息

• Reactions of Monomeric [1,2,4-(Me₃C)₃C₅H₂]₂CeH and CO with or without H₂:  An Experimental and Computational Study
  作者：Evan L. Werkema、Laurent Maron、Odile Eisenstein、Richard A. Andersen

  DOI：10.1021/ja066482h

  日期：2007.3.1

  Addition of CO to [1,2,4-(Me3C)3C5H2]2CeH, CeH, in toluene yields the cis-( Ce)2(μ-OCHCHO), in which the cis-enediolate group bridges the two metallocene fragments. The cis-enediolate quantitatively isomerizes intramolecularly to the trans-enediolate in C6D6 at 100 °C over 7 months. When the solvent is pentane, Ce(OCH2)Ce forms, in which the oxomethylene group or the formaldehyde dianion bridges the

  将 CO 添加到甲苯中的 [1,2,4-(Me3C)3C5H2]2CeH,CeH 中产生顺式-(Ce)2(μ-OCHCHO)，其中顺式烯二醇基团桥接两个茂金属片段。顺式烯二醇在 7 个月内在 100 °C 下在 C6D6 中定量异构化为反式烯二醇。当溶剂为戊烷时，会形成 Ce(OCH2)Ce，其中氧亚甲基或甲醛二价阴离子桥接两个茂金属片段。顺式烯二醇被认为是通过将 CO 插入 Ce(OCH2)Ce 的 Ce-C 键中形成的，生成 CeOCH2COCe。顺式烯二醇酯的立体化学由 OCH2CO 片段中的 1,2-氢位移决定，该片段具有相对于卡宾孤对的 OC(H2) 键反周面。桥接氧亚甲基络合物与 H2 反应，但不与 CH4 反应，得到 CeOMe，它也是 CeH 与 CO 和 H2 的混合物反应的产物。氧亚甲基络合物与 CO 反应生成顺式烯二醇络合物。C5H5 模型茂金属的 DFT 计算表明.
• Splitting a C–O bond in dialkylethers with bis(1,2,4-tri-tert-butylcyclopentadienyl)cerium hydride does not occur by a σ-bond metathesis pathway: a combined experimental and DFT computational study
  作者：Evan L. Werkema、Ahmed Yahia、Laurent Maron、Odile Eisenstein、Richard A. Andersen

  DOI：10.1039/c0nj00261e

  日期：——

  The addition of diethylether to [1,2,4(Me3C)3C5H2]2CeH, abbreviated Cp′2CeH, gives Cp′2CeOEt and ethane. Similarly, di-n-propyl- or di-n-butylether gives Cp′2Ce(O-n-Pr) and propane or Cp′2Ce(O-n-Bu) and butane, respectively. Using Cp′2CeD, the propane and butane contain deuterium predominantly in their methyl groups. Mechanisms, formulated on the basis of DFT computational studies, show that the reactions begin by an α- or β-CH activation with comparable activation barriers, but only the β-CH activation intermediate evolves into the alkoxide product and an olefin. The olefin then inserts into the Ce–H bond forming the alkyl derivative, Cp′2CeR, which eliminates alkane. The α-CH activation intermediate is in equilibrium with the starting reagents, Cp′2CeH and the ether, which accounts for the deuterium label in the methyl groups of the alkane. The one-step σ-bond metathesis mechanism has a much higher activation barrier than either of the two-step mechanisms.

  将二乙醚添加到[1,2,4(Me3C)3C5H2]2CeH，简称为Cp²2CeH，生成Cp²2CeOEt和乙烷。同样，二正丙醚或二正丁醚分别生成Cp²2Ce(O-n-Pr)和丙烷，或Cp²2Ce(O-n-Bu)和丁烷。使用Cp²2CeD时，丙烷和丁烷的甲基中主要含有氘。基于DFT计算研究制定的机制显示，反应始于α-或β-CH活化，其活化能障相当，但只有β-CH活化中间体会演变为醇盐产物和烯烃。然后，烯烃插入Ce–H键形成烷基衍生物Cp²2CeR，并消除烷烃。α-CH活化中间体与起始试剂Cp²2CeH和醚处于平衡状态，这解释了烷烃甲基中的氘标签。一步σ键重排机制的活化能障远高于任何两步机制。
• Cleaving bonds in CH₃OSO₂CF₃with [1,2,4-(Me₃C)₃C₅H₂]₂CeH; an experimental and computational study
  作者：Evan L. Werkema、Ludovic Castro、Laurent Maron、Odile Eisenstein、Richard A. Andersen

  DOI：10.1039/c2nj40624a

  日期：——

  The reaction at 20 °C of the metallocenelanthanide hydride, [1,2,4-(Me3C)3C5H2]2CeH, , and excess methyltrifluoromethanesulfonate, CH3OSO2CF3, results in formation of , , and the bimetallic complex . The metallocenes , , and react with excess CH3OSO2CF3 to form , CH3OCH3, CH3F, and (CH3O)2SO, respectively, at 20 °C. Thus, the net reaction is but the pathway is not a direct methyl transfer. Comparison of the reactivity of CH3OSO2CF3 and CH3OSO2CH3 (Werkema et al., Organometallics, 2012, 31, 870) is revealing since both form a similar set of products but the rates of reaction of CH3OSO2CF3 are faster. The bimetallic complex, in which the SO32− anion bridges two fragments, is unique in organometallic chemistry. The 1H NMR spectrum is fluxional at 20 °C and the low temperature spectrum is consistent with the geometry observed in the solid state. Density Functional Theory (DFT) calculations of the Gibbs energy profiles for the reaction of CH3OSO2CF3 with show that the CH-bond activation and direct CH3 group transfer have similar activation energy barriers. This contrasts with what is observed in the reaction of with CH3OSO2CH3, where CH-bond activation at the SCH3 group is preferred. Remarkably, the activation energy barriers for C–O-bond cleavage are similar in CH3OSO2CH3 and CH3OSO2CF3, which is traced to the calculated small exoergicity of −1.7 kcal mol−1 for the reaction of . This contrasts, perhaps, with conventional wisdom that overemphasizes the effect of the electron-withdrawing ability of the CF3 group on the chemical and physical properties of sulfonate esters.

  这是一项关于金属茂镧系氢化物[1,2,4-(Me3C)3C5H2]2CeH与甲基三氟甲磺酸酯(CH3OSO2 )在20°C下的反应研究。主要发现如下： 1. 反应生成了双金属配合物，其中SO32-阴离子桥连两个金属茂片段，这在有机金属化学中是独特的。 2. 与 OSO2 相比， OSO2 形成类似的产物，但反应速率更快。 3. 该双金属配合物在20°C时的1H NMR谱图显示流动性，低温谱图与固态观察到的构型一致。 4. DFT计算表明， OSO2 与金属茂反应时，C-H键活化和直接 基团转移具有相似的活化能垒。 5. 这与 OSO2 的反应不同，后者倾向于在S 基团发生C-H键活化。 6. 有趣的是， OSO2 和 OSO2 的C-O键断裂活化能垒相似，这表明传统观点可能过分强调了CF3基团的电子吸引能力对磺酸酯化学和物理性质的影响。 这个研究揭示了反应机理并不是简单的甲基转移，而是涉及更复杂的过程。
• Bridging Silyl Groups in σ-Bond Metathesis and [1,2]-Shifts. Experimental and Computational Study of the Reaction between Cerium Metallocenes and MeOSiMe₃
  作者：Evan L. Werkema、Ahmed Yahia、Laurent Maron、Odile Eisenstein、Richard A. Andersen

  DOI：10.1021/om1003286

  日期：2010.11.8

  SiMe3 reactions have in common a pentacoordinate silicon at the transition states. A molecular orbital analysis illustrates the connection between these two Si−O bond cleavage reactions and traces the reason why they occur for a silyl but not for an alkyl group to the difference in energy required to form a pentacoordinate silicon or carbon atom in the transition state. This difference clearly distinguishes

  CP'的反应2 CEH（CP'= 1,2,4-（ME 3 C）3 c ^ 5 ħ 2）与MeOSiMe 3给出了CP' 2 CeOMe和HSiMe 3，以及金属环CP的反应'[（箱3 C）2 C ^ 5 ħ 2 C（Me）的2 CH 2 ]的Ce与MeOSiMe 3个产率CP' 2 CeOCH 2森达3，从假想的CP'形成2切克2 OSiMe 3通过[1,2]移位也称为甲硅烷基-维蒂希重排。尽管两种铈产物都是醇盐，但它们是通过不同的途径形成的。对模型金属茂CP 2 CeH和MeOSiMe 3反应的DFT计算表明，最低能量途径是H在Ce进行OMe交换的H，这是通过SiMe 3交换伙伴时通过σ键易位过渡态发生的。CP 2 CeOCH 2 SiMe 3的形成是通过CP 2 CeCH 2 OSiMe 3中SiMe 3基团的低活化势垒[1,2]位移发生的。模型金属环CP [C 5 H 4的计算C（Me）2
• Hydrogen for Fluorine Exchange in CH₄_-<i>_x</i>F<i>_x</i> by Monomeric [1,2,4-(Me₃C)₃C₅H₂]₂CeH:  Experimental and Computational Studies
  作者：Evan L. Werkema、Elsa Messines、Lionel Perrin、Laurent Maron、Odile Eisenstein、Richard A. Andersen

  DOI：10.1021/ja0504800

  日期：2005.6.1

  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.