从分子 σ-化合物中脱的室温无接收器
Alasdair I McKay1, Alexander J Bukvic1, Bengt E Tegner2
1Chemistry Research Laboratories, University of Oxford , Oxford OX1 3TA , United Kingdom.
Journal of the American Chemical Society
|June 28, 2019
概括
这项研究使用固态分子有机金属化学在室温下激活中的C-H键,从而实现非氧化脱. 这一突破为催化功能化提供了新的途径.
科学领域:
- 有机金属化学
- 催化剂
- 固态化学
背景情况:
- 通过C-H激活进行轻的非氧化催化脱是具有挑战性的,因为其具有高的内热性和不利的热力学.
- 基是较弱的连接体,使其在C-H激活之前难以与金属中心结合.
- 通常需要高温或牺牲性受体来克服热力学障碍.
研究的目的:
- 用固态分子有机金属化学 (SMOM-chem) 在温和条件下激活基C-H键的新方法.
- 准备和描述明确的合体.
- 研究这些复合物的脱机制和动力学.
主要方法:
- 通过固体/气体单晶转化为前体复合物的-西格玛复合物的合成 ([Rh ((Cy2PCH2CH2PCy2) ((Alkane)) [BArF4]).
- 与D2进行固体气体H/D交换实验,以探测C-H键的反应性.
- 可变温度固态核磁共振 (NMR) 光谱和周期密度功能理论 (DFT) 计算以研究流动过程和反应机制.
- 动力学研究,包括动力学同位素效应 (KIEs),以及使用经典化学动力学或约翰逊-梅尔-阿弗拉米-科尔莫戈罗夫 (JMAK) 模型的建模.
主要成果:
- 精确的异芽素和环素西格玛复合物得到了成功的准备和表征.
- 在真空或Ar流下,在298K发生了自发的,无受体的化.
- 对于循环脱的动态同位素效应 (kH/kD = 3.6 ((5) 和10.8 ((6)) 表示C-H激活作为速度决定的步骤.
- 定期的DFT计算支持实验发现,预测激活障碍并阐明涉及C-H键延长和β-H转移的机制.
结论:
- 固态分子有机金属化学 (SMOM-chem) 允许在温和条件下制备基西格玛复合物及其随后的脱.
- 该研究提供了脱中C-H激活的直接实验证据,得到了动力和计算数据的支持.
- 这种方法为的催化功能提供了一个有希望的新途径,克服了热力学限制.
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