Visible-Light Photocatalysis of C(sp3 )-H Fluorination by the Uranyl Ion: Mechanistic Insights.
Visible-Light Photocatalysis of C(sp3 )-H Fluorination by the Uranyl Ion: Mechanistic Insights.
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DOI：
10.1002/anie.201806554
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发表时间：
2018-09
影响因子：
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通讯作者：
Liangliang Wu;Xiaoyan Cao;Xuebo Chen;Weihai Fang;M. Dolg
中科院分区：
文献类型：
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作者：
Liangliang Wu;Xiaoyan Cao;Xuebo Chen;Weihai Fang;M. Dolg
铀酰双阳离子对脂肪族化合物的 C(sp3 )-H 键显示出光催化活性，但对烷基苯或环酮的 C(sp3 )-H 键没有光催化活性。对相应机制的理论见解仍然有限。包括相对论效应在内的多构型从头计算揭示了蓝光下铀酰催化 C-H 氟化的固有电子转移机制。沿着三线态的反应路径，发现铀酰部分的富电子氧引发的氢原子夺取是限速步骤。随后的步骤，即以协同异步方式断裂 N-F 和 O-H 键、生成目标氟化产物以及光催化剂的回收，几乎是无障碍的。此外，反应基质之间的单电子转移在整个光催化循环中起着重要作用。
The uranyl dication shows photocatalytic activity towards C(sp3 )-H bonds of aliphatic compounds, but not towards those of alkylbenzenes or cyclic ketones. Theoretical insights into the corresponding mechanisms are still limited. Multi-configurational ab initio calculations including relativistic effects reveal the inherent electron-transfer mechanism for the uranyl catalyzed C-H fluorination under blue light. Along the reaction path of the triplet state it was found that the hydrogen atom abstraction triggered by the electron-rich oxygen of the uranyl moiety is the rate-limiting step. The subsequent steps, that is, N-F and O-H bond breakage in a manner of concerted asynchronicity, generation of the targeted fluorinated product, and recovery of the photocatalyst are nearly barrierless. Moreover the single electron transfer between the reactive substrates plays a fundamental role during the whole photocatalytic cycle.