Cp2Ta[CH2B(C6F5)3]CH3 | 278609-27-1

• 英文名称: Cp2Ta[CH2B(C6F5)3]CH3
• CAS: 278609-27-1
• 化学式: C₃₀H₁₅BF₁₅Ta
• 分子量: 852.184
• InChiKey: PVCZVPMXGOTGCU-UHFFFAOYSA-N

反应信息

• 作为反应物：
  描述：

  Cp2Ta[CH2B(C6F5)3]CH3 、 异氰酸叔丁酯 以 四氢呋喃 为溶剂， 以83%的产率得到
  参考文献：
  名称：

  合成和反应性通过B的反应通过基态α-抓氢键稳定Tantalocene两性离子的（C 6 ˚F 5）3与CP ' 2的Ta（CH 2）（CH 3）（CP'= C 5 H ^ 5，C 5 H 4我）

  摘要：

  当全氟苯基-取代的甲硼烷B（C形成两性离子tantalocene衍生物6 ˚F 5）3与tantalocene甲基亚甲基络合物CP '反应2的Ta（CH 2）（CH 3）（CP'= C 5 H ^ 5，C 5 H 4 Me）。产物来自亚甲基配体的硼烷攻击，其特征是强烈的基态α-声波相互作用，叔丁基异氰化物的插入仅发生在不良的Ta-C键中，产生亚氨基酰基两性离子。

  DOI：

  10.1021/om000176+
• 作为产物：
  描述：

  (η(5)-C5H5)2Ta(=CH2)(CH3) 、 三(五氟苯基)硼烷 以 甲苯 为溶剂， 以91%的产率得到Cp2Ta[CH2B(C6F5)3]CH3
  参考文献：
  名称：

  合成和反应性通过B的反应通过基态α-抓氢键稳定Tantalocene两性离子的（C 6 ˚F 5）3与CP ' 2的Ta（CH 2）（CH 3）（CP'= C 5 H ^ 5，C 5 H 4我）

  摘要：

  当全氟苯基-取代的甲硼烷B（C形成两性离子tantalocene衍生物6 ˚F 5）3与tantalocene甲基亚甲基络合物CP '反应2的Ta（CH 2）（CH 3）（CP'= C 5 H ^ 5，C 5 H 4 Me）。产物来自亚甲基配体的硼烷攻击，其特征是强烈的基态α-声波相互作用，叔丁基异氰化物的插入仅发生在不良的Ta-C键中，产生亚氨基酰基两性离子。

  DOI：

  10.1021/om000176+

文献信息

• Isocyanide insertion reactions into the Ta—C bonds of cationic and zwitterionic tantalocenes
  作者：Kevin S Cook、Warren E Piers、Brian O Patrick、Robert McDonald

  DOI：10.1139/v03-051

  日期：2003.11.1

  The insertion of isonitriles R' NC (R' = t-Bu, C₆H₁₁, CH₂C₆H₅) occurs exclusively into the Ta—CH₂ bonds of the zwitterionic compounds (C₅H₄R)₂Ta[CH₂B(C₆F₅)₃]CH₃ (R = H, 1a; R = CH₃, 1b) at relatively slow rates at room temperature to form N-out isomers as the sole kinetic products. By comparison, insertion of the same isonitrile substrates into a Ta—CH₃ bond of the non-zwitterionic analogs [(C₅H₄R)₂Ta(CH₃)₂][A] (R = H, A = B(C₆F₅)₄, 3a; R = CH₃, A = BF₄, 3b) occurs much more rapidly, again to form N-out isomers exclusively under kinetic conditions. The difference in rate is attributed to the presence of a ground state α-agostic interaction in the zwitterionic compounds, which is not featured in the dimethyl ion pairs. All of the N-out isomers formed undergo thermal and irreversible conversion to the corresponding N-in isomers at rates that are conveniently followed by ¹H NMR spectroscopy. The rates were studied at different temperatures to obtain activation parameters for each transformation. The rate and activation trends for this isomerization were analyzed as a function of the structural changes in the compounds. It was found that the rate decreased as the steric bulk of the isonitrile substitutent R' increased and that the rates were faster for the series that incorporated the more electron-donating C₅H₄CH₃ ancillary ligand. Furthermore, isomerization rates for the zwitterionic N-out compounds were faster than those found in the non-zwitterionic series. This study represents one of the more extensive kinetic analyses of the rate of N-out to N-in isomerization as a function of structural changes. The observations are consistent with the mechanistic picture that has been developed for this process, involving dissociation of the η² iminoacyl ligand, rotation about the M—C_iminoacyl bond and recoordination to the inside site of the metallocene wedge. Key words: cationic metallocenes, isocyanide insertion, agostic interactions, tantalum.

  对偶极化合物(C5H4R)2Ta[ B(C6F5)3] (R = H, 1a; R = CH3, 1b)中，异腈R'NC (R' = t-Bu, C6H11, C6H5)的插入仅发生在Ta-CH2键上，且在室温下速率相对较慢，形成N-out异构体作为唯一的动力学产物。相比之下，相同的异腈底物插入非偶极类似物[(C5H4R)2Ta( )2][A] (R = H, A = B( )4, 3a; R = , A = BF4, 3b)中的Ta- 键则发生得更快，同样仅形成N-out异构体。速率差异归因于偶极化合物中存在基态α-咬合作用，而在二甲基离子对中不存在。所有形成的N-out异构体均经历热力学和不可逆的转化，形成相应的N-in异构体，其速率可通过1H NMR光谱方便地跟踪。通过在不同温度下研究速率，获得了每种转化的活化参数。分析了异构化反应的速率和活化趋势与化合物结构变化的关系。发现随着异腈取代基R'的空间位阻增加，速率降低；对于包含更多电子供体的C5H4 辅助配体的系列，速率较快。此外，偶极化的N-out化合物的异构化速率比非偶极化系列中的速率更快。该研究代表了结构变化作为N-out到N-in异构化反应速率的函数的更广泛的动力学分析之一。观察结果与已经发展的机理图像一致，涉及到η2亚胺酰基配体的解离，M-Ciminoacyl键的旋转和重新配位到金属茂环楔形内部位点。关键词：阳离子茂金属化合物、异腈插入、咬合相互作用、钽。