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Electrophotocatalysis with a Trisaminocyclopropenium Radical Dication
Author(s) -
Huang He,
Strater Zack M.,
Rauch Michael,
Shee James,
Sisto Thomas J.,
Nuckolls Colin,
Lambert Tristan H.
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201906381
Subject(s) - dication , photochemistry , chemistry , oxidizing agent , radical ion , photoexcitation , catalysis , photocatalysis , photoredox catalysis , electron transfer , visible spectrum , ion , excited state , organic chemistry , materials science , physics , optoelectronics , nuclear physics
Visible‐light photocatalysis and electrocatalysis are two powerful strategies for the promotion of chemical reactions. Here, these two modalities are combined in an electrophotocatalytic oxidation platform. This chemistry employs a trisaminocyclopropenium (TAC) ion catalyst, which is electrochemically oxidized to form a cyclopropenium radical dication intermediate. The radical dication undergoes photoexcitation with visible light to produce an excited‐state species with oxidizing power (3.33 V vs. SCE) sufficient to oxidize benzene and halogenated benzenes via single‐electron transfer (SET), resulting in C−H/N−H coupling with azoles. A rationale for the strongly oxidizing behavior of the photoexcited species is provided, while the stability of the catalyst is rationalized by a particular conformation of the cis ‐2,6‐dimethylpiperidine moieties.