# Copper–sulfone complexes release carbon radicals under visible light via irreversible MLCT

- Published: 2026-11-05 04:57 UTC
- Section: Science › Chemistry
- Tags: metal-to-ligand charge transfer, copper heteroaryl sulfone complexes, C–S bond cleavage, carbon-centered radicals, visible light photochemistry, C–H fluoroalkylation, halogen-atom transfer, perfluorocyclobutyl iodide, trifluoromethyl radical
- URL: https://realtech.media/news/rt-ee53b1afe106e2dc1fa41aac_copper_sulfone_complexes/

**Chemists at the Shanghai Institute of Organic Chemistry isolated copper–heteroaryl sulfone complexes that cleave a C–S bond under visible light, producing alkyl radicals.**

![Copper–sulfone complexes release carbon radicals under visible light via irreversible MLCT](https://sgzwpqqelzmajkcubgkl.supabase.co/storage/v1/object/public/rt-media/2026/11/6e36d5b67dfc8b7d.jpg)
*U5780710, Wikimedia Commons, CC BY-SA 4.0*

Researchers from the Shanghai Institute of Organic Chemistry (Chinese Academy of Sciences) and ShanghaiTech University, with Xiao-Song Xue and Jinbo Hu as corresponding authors, report a class of isolable copper–heteroaryl sulfone complexes. According to the material from static-content.springer.com, under visible light these complexes undergo irreversible fragmentation driven by metal-to-ligand charge transfer (MLCT). A C–S bond within the coordinated sulfone ligand breaks and carbon-centered radicals form [1]. The work was published in Nature.

MLCT is a fundamental photoinduced process underlying a broad range of energy- and electron-transfer events. Without productive substrate engagement, the MLCT excited state usually relaxes to the ground state through photophysical deactivation, so the process is largely reversible [1]. In the new complexes the excited state instead leads to bond cleavage.

## Mechanism and scope of radicals

The authors report that spectroscopic and computational studies support the formation of MLCT-derived excited states and a low-barrier pathway for C–S bond cleavage [1]. The source data include DFT excitation-energy calculations for a copper complex designated Cu-2. The reactivity is largely independent of the reduction potentials of the corresponding free sulfones [1]. This allows the generation of fluoroalkyl radicals and of non-fluorinated tertiary, secondary and primary alkyl radicals, including methyl [1].

## Synthetic applications

The authors demonstrate the platform in copper-catalyzed C–H fluoroalkylation of arenes and terminal alkynes [1]. In a second application, trifluoromethyl radicals generated through MLCT initiate halogen-atom transfer (XAT) from perfluorocyclobutyl iodide (I-FCB). This gives radical perfluorocyclobutylation–iodination of alkenes, which the authors describe as addressing a longstanding challenge in introducing perfluorocyclobutyl motifs [1].

This is a laboratory study of molecular complexes and model reactions. The available material does not give yields, the number of substrates or the reaction conditions.

## Sources

1. [static-content.springer.com](https://static-content.springer.com/esm/art%3A10.1038%2Fs41586-026-11368-9/MediaObjects/41586_2026_11368_MOESM2_ESM.zip)
2. [Nature](https://www.nature.com/articles/s41586-026-11368-9)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-ee53b1afe106e2dc1fa41aac_copper_sulfone_complexes/