阴离子哈夫西复合物及其在与Si-H和C-H键的西格玛键转化过程中的增强反应性
1Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, USA.
Journal of the American Chemical Society
|August 2, 2003
概括
这项研究探讨了与化合物反应的 hafnium silyl 复合物. 研究人员观察了兹维特和酸哈夫的合物复合物的形成,详细说明了它们在西格玛键转化和C-H激活反应中的稳定性和反应性.
科学领域:
- 有机金属化学 有机金属化学
- 主群 化学 化学
- 催化剂是一种催化剂.
背景情况:
- 早期过渡金属的有机基复合物在催化过程中至关重要.
- 复合物与易斯酸如B(C6F5) 3的反应性尚未完全理解.
- 了解这些反应可以导致新的催化途径的CH激活和变换.
研究的目的:
- 为了研究混合环和bis ((cyclopentadienyl) hafnium西甲基复合物的反应与B ((C6F5) 3.3.
- 为了描述由此产生的zwitterionic和cationic hafnium silyl复合体.
- 探索这些复合体在西格玛键转化和C-H激活反应中的反应性.
主要方法:
- 合成和表征的哈夫西甲基复合物.
- 哈复合物的反应与三五甲 (BC6F5) 3).
- 光谱分析 (NMR) 和X射线晶体学用于结构确定.
- 动力学研究以阐明反应机制,包括同位素效应测量.
主要成果:
- 从CpCp*Hf[Si(SiMe3) 3) Me.Me.中形成一个稳定的Zwitterionic hafnium silyl复合物[CpCp*HfSi(SiMe3) 3][MeB(C6F5) 3].
- 合成从Cp2Hf(SiR3) Me前体中化哈夫西复合物.
- 对Cp2Hf{SitBuPh2}{mu-Me) B{C6F5}3的分离和表征,揭示了它的结构和特性.
- 观察与Mes2SiH2的西格玛键转化,产生HSitBuPh2和具有α-毒性Si-H相互作用的活性物种.
- 证明C-H键与和的激活,形成烯和烯复合物.
- 动态数据支持C-H键激活的协调过渡状态机制.
结论:
- 哈夫尼基复合物与B(C6F5) 3表现出多样化的反应性,产生双双的zwitterionic和cationic物种.
- 阴阳性哈夫基复合物能够进行西格玛键转化和C-H键激活.
- 碳化合物激活机制通过协调过渡状态进行,得到动力和同位素证据的支持.
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