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Carbon radical generation by irreversible metal-to-ligand charge transfer
Nature
(2026) Cite this article
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Metal-to-ligand charge transfer (MLCT) is a fundamental photoinduced process that underpins a broad range of energy- or electron-transfer events1,2. In the absence of productive substrate engagement, the MLCT excited state typically relaxes to the ground state via photophysical deactivation, reflecting its largely reversible character3,4. Here we report a class of isolable copper–heteroaryl sulfone complexes that, upon visible light irradiation, undergo an irreversible MLCT-driven fragmentation through C–S bond cleavage within the coordinated sulfone ligand, generating carbon-centered radicals. Spectroscopic and computational studies support the formation of MLCT-derived excited states and a low-barrier pathway for C–S bond cleavage. This reactivity is largely independent of the reduction potentials of the corresponding free sulfones, enabling the generation of fluoroalkyl and non-fluorinated tertiary, secondary, and primary (even methyl) alkyl radicals. We demonstrate the utility of this platform in copper-catalyzed C–H fluoroalkylation of arenes and terminal alkynes. Leveraging these MLCT-generated trifluoromethyl radicals to initiate halogen-atom transfer (XAT) from perfluorocyclobutyl iodide (I-FCB), we also achieve radical perfluorocyclobutylation–iodination of alkenes, addressing a longstanding challenge in the incorporation of perfluorocyclobutyl motifs.
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These authors contributed equally: Zhiqiang Wei, Xiang Li, Lin Xiao, Yu He
State Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
Zhiqiang Wei, Xiang Li, Lin Xiao, Yu He, Zhao Liu, Kaidi Zhu, Chuanfa Ni, Xiao-Song Xue & Jinbo Hu