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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
结合的实验和计算研究,从 (PCP) Ir的Bis () 碳化合物复合物中进行碳-碳还原性消除
Rajshekhar Ghosh1, Thomas J Emge, Karsten Krogh-Jespersen
1Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903, USA.
Journal of the American Chemical Society
|August 6, 2008
概括
在有机金属化学中,减少碳-碳键的消除是关键. 庞大的配体的固体阻碍显著减缓了这种反应,影响了催化剂的设计.
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.
- 反应动力学反应动力学
背景情况:
- 减少消除碳-碳键是许多催化循环中的关键步骤.
- 了解C-C键的减少性消除的动力学对于设计高效的催化剂至关重要.
- 之前对六坐标复合体的研究因先前的带损失而复杂化.
研究的目的:
- 合成和表征五坐标的复合物,以直接测量C-C减小性消除率.
- 研究固体和电子因素对C-C键形成的动力学的影响.
- 通过实验数据和计算方法阐明减少消除的机制.
主要方法:
- 一系列具有不同R和R'群的五坐标复合物的合成.
- 测量几个复合体的C-C减少性消除的绝对速率.
- 密度函数理论 (DFT) 计算分析过渡状态和反应障碍.
主要成果:
- 建立了减少性消除速率的顺序:乙化物 < 乙烯基 ≈ Me < Ph.
- 鉴定了大量的氨酸三基团的固体阻碍作为减缓排泄的主要因素,特别是对烯和乙烯基团.
- DFT的计算表明,/乙烯基组的旋转受到重的配体的阻碍,增加了激活障碍.
结论:
- 立体效应,特别是由重的配体阻碍基/乙烯基组旋转,是C-C减小性消除率的关键决定因素.
- 不太受硬质阻碍的复合体对C-C消除的激活障碍明显较低.
- 该研究提供了对C-C减小消除机制的基本见解,这对催化剂开发至关重要.
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