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Visible‐Light Photocatalysis of C(sp 3 )‐H Fluorination by the Uranyl Ion: Mechanistic Insights
Author(s) -
Wu Liangliang,
Cao Xiaoyan,
Chen Xuebo,
Fang Weihai,
Dolg Michael
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201806554
Subject(s) - uranyl , chemistry , photochemistry , photocatalysis , dication , catalytic cycle , moiety , electron transfer , catalysis , hydrogen atom , reactive intermediate , ab initio , ion , stereochemistry , organic chemistry , alkyl
Abstract The uranyl dication shows photocatalytic activity towards C(sp 3 )−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.