环二烯基替代剂对4组金属中减小性消除反应的影响:动力学,机制和应用到二激活
Jaime A Pool1, Emil Lobkovsky, Paul J Chirik
1Contribution from the Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA.
Journal of the American Chemical Society
|February 20, 2003
概括
硬质要求高的替代剂增强了conocene复合体中的减少性消除. 一个新型的复合体,具有重的基组,促进了二激活,形成了一个前所未有的三重二复合体,具有创纪录的N-N键.
科学领域:
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
- 材料科学 材料科学 材料科学
背景情况:
- 基复合物在有机金属化学和催化过程中至关重要.
- 减少性消除是这些复合物的关键反应途径.
- 了解替代剂对反应性的影响对于催化剂设计至关重要.
研究的目的:
- 调查环丁 (Cp) 替代剂对conocene异布化复合物的减少性消除率的影响.
- 通过同位素标记阐明了还原性消除过程的机制和速率决定步骤.
- 设计和合成一种新型的conocene复合物,用于增强还原性消除和二激活.
主要方法:
- 用不同的Cp替代剂测量减少性消除率的动力学研究.
- 同位素标记实验 (例如,标记) 来探测反应机制.
- 合成和描述新的conocene复合物,包括X射线衍射和溶液磁敏度测量.
主要成果:
- 降低性消除率在对硬质要求较高的Cp替代物 (例如,三,三甲基) 中略有增加.
- 合成了一种新的复合物,Cp'2Zr(isobutyl) H (Cp' = eta(5) -C5H3-1,3-(SiMe3) 2),表现出易于减少的消除和二激活.
- 由此产生的二复合物,[Cp'2Zr]2(N2),表现出在金属二复合物中观察到的最长的N-N键 (1.47 Å),并且是基态三重体.
结论:
- 在Cp配体上的体质量在调节conocene异布化的减少性消除速率方面发挥着重要作用.
- 这种新型的基复合物能够有效地激活二,从而产生独特的三重二物种.
- 机械学研究表明,二复合物形式通过与环金属化化的反应形成,而不是通过直接的还原性消除.
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