测试不平衡的CPET反应的极限:通过Co (III) -Oxo复合体进行H原子抽象的机械交叉
Norman Zhao1, McKenna K Goetz1, Joseph E Schneider1
1Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States.
Journal of the American Chemical Society
|March 3, 2023
概括
这项研究表明,增加氧复合物的基本性可以改变C-H键激活机制. 非常基本的复合体从协同的质子电子转移转向阶段性路径,影响反应速率.
科学领域:
- 有机金属化学
- 催化剂
- 反应机制
背景情况:
- 过渡金属-氧复合物是氧化反应中的关键中间体,特别是C-H键激活.
- 在C-H激活中,反应速率通常与通过协同质子电子转移 (CPET) 的基质键解离自由能量有关.
- 涉及基质/金属酸性/酸性或氧化还原潜力的替代阶段性途径也可以影响反应动态.
研究的目的:
- 通过过渡金属-氧化合物来研究基度控制的C-H键激活的极限.
- 合成和研究一种更基本的氧复合物,PhB(AdIm) 3CoIIIO,并将其反应性与较少的基本类型进行比较.
- 在C-H和O-H键激活中探索协同和阶段性路径之间的机制交叉.
主要方法:
- 合成一种新的,更基本的终端氧复合物,PhB ((AdIm) 3CoIIIO.
- 使用原子供体和基底的反应性研究.
- 质子转移 (PT) 和电子转移 (ET) 过程的热力学分析.
主要成果:
- 较为基本的PhB ((AdIm) 3CoIIIO复合体与PhB ((Im) 3CoIIIO相比表现出更强的不平衡CPET反应性.
- 基质的O-H激活显示了从CPET到阶段性质子转移-电子转移 (PTET) 的机械转移.
- 确定了协同和阶段反应之间的热力学交叉点.
结论:
- 基本性在决定氧复合物的C-H键激活机制方面起着至关重要的作用.
- 极度不平衡的系统可以实现快速的CPET速率,直到发生机械交叉到阶段性路径.
- 这种交叉点导致产品形成较慢,突出显示了协调和阶段性反应之间的微妙平衡.
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