了解在催化C-H键功能化反应中的预催化剂激活和特异化
Jonathan B Eastwood1, L Anders Hammarback1, Thomas J Burden1
1Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom.
这项研究揭示了催化C-H功能化最初在前催化剂激活后形成溶剂复合物. 随后的连接物替代是动力学控制的,在达到热力学平衡之前影响产品分布.
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.
- 频谱学是一种光谱学.
背景情况:
- 复合体是C-H键功能化的关键催化剂.
- 了解前催化剂激活后形成的初始物种是控制反应结果的关键.
- 时间分辨率光谱学为快速反应中间体提供了洞察力.
研究的目的:
- 为了研究在催化C-H功能化过程中形成的过渡物种.
- 阐明在前催化剂激活后控制连接物替代的动力因素.
- 为了将基质特性与反应路径和产品选择性相关联.
主要方法:
- 时间分辨率红外光谱 (TR-IR) 用于在纳米秒到微秒的时间尺度上监测物种形成.
- 使用特定的预催化剂与循环金属化配体 ([Mn(C^N) ((CO) 4)).
- 密度函数理论 (DFT) 计算以探测基质-连接体亲和力.
主要成果:
- 由预催化剂引起的光 CO 分离产生初始溶剂复合物 ([Mn(C^N) ((CO) 3 ((toluene))).
- 随后的溶剂被含的配体 (2a或2b) 替代,发生在纳秒时间尺度上.
- 与 fenylacetylene 的竞争反应导致 alkine 插入或连接体替代,取决于基质 (2a 与 2b).
- DFT计算表明,对的不同基质亲和度决定了反应路径.
结论:
- 在前催化剂激活后立即进行特异化是一个动力控制的过程.
- 溶剂协调是最初的步骤,其次是动力控制的连接体替代.
- 观察到的反应结果的差异归因于基质对中心的不同亲和力.
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