Abstract
Precious metal complexes remain ubiquitous in photoredox catalysis (PRC) despite concerted efforts to find more earth-abundant catalysts and replacements based on 3d metals in particular. Most otherwise plausible 3d metal complexes are assumed to be unsuitable due to short-lived excited states, which has led researchers to prioritize the pursuit of longer excited-state lifetimes through careful molecular design. However, we report herein that the C−H arylation of pyrroles and related substrates (which are benchmark reactions for assessing the efficacy of photoredox catalysts) can be achieved using a simple and readily accessible octahedral bis(diiminopyridine) cobalt complex, [1-Co](PF6)2. Notably, [1-Co]2+ efficiently functionalizes both chloro- and bromoarene substrates despite the short excited-state lifetime of the key photoexcited intermediate *[1-Co]2+ (8 ps). We present herein the scope of this C−H arylation protocol and provide mechanistic insights derived from detailed spectroscopic and computational studies. These indicate that, despite its transient existence, reduction of *[1-Co]2+ is facilitated via pre-assembly with the NEt3 reductant, highlighting an alternative strategy for the future development of 3d metal-catalyzed PRC.
Original language | English |
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Article number | e202405780 |
Number of pages | 13 |
Journal | Angewandte Chemie - International Edition |
Volume | 63 |
Issue number | 28 |
Early online date | 1 May 2024 |
DOIs | |
Publication status | Published - 8 Jul 2024 |
Data Availability Statement
The data that support the findings of this study are available in the supplementary material of this article. All optimized structures are provided as xyz files in a separate zip-Archive, available free of charge at https://doi.org/10.5281/zenodo.10528904.Funding
The project was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)\u2014TRR 325\u2014444632635 (projects A4, A5 and C1). Open Access funding enabled and organized by Projekt DEAL.
Funders | Funder number |
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Deutsche Forschungsgemeinschaft | TRR 325—444632635 |
Deutsche Forschungsgemeinschaft |
Keywords
- arylation
- cobalt
- electron-transfer
- photoredox catalysis
- quantum chemistry
ASJC Scopus subject areas
- Catalysis
- General Chemistry