rac-ethylenebis(1-indenyl)hafnium dimethyl | 136050-55-0

• 英文名称: rac-ethylenebis(1-indenyl)hafnium dimethyl
• 英文别名: 1,2-ethanediylbis(η⁵-1-indenyl)dimethylhafnium；1,2-ethanediylbis(η5-1-indenyl)dimethylhafnium
• CAS: 136050-55-0；785702-13-8
• 化学式: C₂₂H₂₂Hf
• 分子量: 464.907
• InChiKey: SFSMKXVZOLLGSZ-UHFFFAOYSA-N

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：
  None
• 氢给体数：
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• 氢受体数：
  None

反应信息

• 作为反应物：
  描述：

  三(五氟苯基)硼烷 、 rac-ethylenebis(1-indenyl)hafnium dimethyl 以 氘代甲苯 为溶剂， 生成 [rac-EBIHfMe][MeB(C₆F₅)₃]
  参考文献：
  名称：

  茂金属离子中的立体化学非刚性

  摘要：

  MEB的动态NMR光谱（C 6 ˚F 5 3 -一系列环取代的锆和含铪茂金属离子，由（RCP）例举的盐2 ZrCH 3 +，其中说明了两个交换过程的一种，具有较低。活化的自由能涉及CH 3基团从一个赤道侧向轨道转移到另一侧，第二个结果来自金属CH 3和B-CH 3基团之间的交换，并讨论了结构变化对交换壁垒的影响和相关性茂金属离子催化的烯烃聚合。

  DOI：

  10.1016/0022-328x(95)00114-6
• 作为产物：
  描述：

  1,2-bis(indenyl)ethane 、 氯化铪 在 CH₃Li 作用下， 以 乙醚 、 正己烷 为溶剂， 以45.3%的产率得到rac-ethylenebis(1-indenyl)hafnium dimethyl
  参考文献：
  名称：

  Comparison of the Regiochemical Behavior of Zirconium and Hafnium in the Polyinsertion of Styrenes

  摘要：

  The hafnocene-based catalyst ethylenebis(1-indenyl)hafnium dichloride/methylalumoxane, as well as its zirconium analogue, is able to oligomerize styrene, p-methylstyrene, and p-tert-butylstyrene in the presence of hydrogen to produce hydrooligomers. The composition of the product mixture compared to that obtained using zirconium-based catalysts indicates that the primary insertion occurs with greater frequency. This difference in regioselectivity is likely to be related to the electronic differences between the two metal centers. Previous experimental and theoretical evidence suggests that increasing the electron density at the incoming metal carbon bond decreases the preference for the secondary insertion; so by exploiting the contribution from the electron-releasing substituent of the monomer and changing the metal center, from zirconium to hafnium, the regiochemistry of insertion can be inverted from secondary to prevailingly primary. The styrene regiochemistry of insertion is engraved into the structure of ethylene styrene copolymers. Some relevant differences can be observed by comparing the C-13 NMR spectra of copolymer obtained with zirconium- and hafnium-based catalysts. In fact the structure of the chains obtained with hafnium, compared to zirconium, shows higher styrene uptake and the presence of styrene homosequences and of regioirregularly arranged units.

  DOI：

  10.1021/om1001342

文献信息

• Interpreting “Acidity” as a Global Property Controlling Comonomer Reactivity in Olefin Polymerization
  作者：Lorella Izzo、Massimo Mella

  DOI：10.1021/om400076k

  日期：2013.6.10

  A possible rationale for the different catalytic behaviors of systems based on rac-(ethylenebis(1-indenyl))zirconium dichloride (rac-EBIZrCl2), rac-(ethylenebis(1-indenyl))hafnium dichloride (rac-EBIHfCl2), and rac-(isopropylidenebis(1-indenyl))zirconium dichloride (rac-iPrBIZrCl(2)) toward ethene-styrene copolymerization has been sought by studying related active systems. For this purpose, the metallocene ion pairs (IPs) rac-EBIZrMe-MeB(C6F5)(3), rac-EBIHfMe-MeB(C6F5)(3), and rac-iPrBIZrMe-MeB(C6F5)(3) have been synthesized and their structures in solution explored with ROESY and pulsed gradient NMR spectroscopy. The energetics of dynamical processes relevant for catalysis that can be used as indicators of the cation acidity have been studied with variable-temperature NMR experiments and density functional theory (DFT). NMR experiments successfully provided IP structural details in solution and also indicated the presence of an intricate dynamic behavior for all the IPs. DFT results, instead, indicated quantitatively how changing the metal and/or the ancillary ligand bridge influences the energetics of the active species and modifies the reaction energy profile. The theoretical results also drew attention to the fact that finding a rationale for the ligand influence on the catalytic behavior of rac-EBIZrCl2/MAO and rac-iPrBIZrCl(2)/MAO in ethene-styrene copolymerization requires not only considering the steric effects but also determining how subtle changes in the ligand sphere affect the capability of the metal center to accept electrons from the counteranion or the olefins.