An Ion-Pair Complex-Enabled Photoinduced Cleavage of the Trifluoromethyl Thianthrenium Salt
Abstract
Trifluoromethyl thianthrenium salts represent valuable reagents in photocatalysis; however, their activation traditionally necessitates external one-electron donors, such as photocatalysts, electron-donor-acceptor complexes. Direct photoexcitation can proceed without exogenous one-electron donors, thereby circumventing the stringent redox potential constraints inherent in the ground and excited states of conventional photocatalytic systems. Such direct excitation facilitates a transition of substrates to an electronically excited state, promoting homolytic cleavage to release the CF 3 • radical. Nevertheless, this process typically requires near-ultraviolet excitation (390 nm) to attain the high-energy excited singlet state of the substrate. In this study, we report a pioneering strategy involving the design of an acid-base ternary ion-pair complex utilising trifluoromethyl thianthrenium salts. In contrast to conventional ion-pair complex catalysis, this methodology eliminates the requirement for a photocatalyst and bypasses the single electron transfer process. This conceptual advancement lowers the activation energy to the excited singlet state of TT-CF 3 OTf, enabling the generation of CF 3 • species via homolytic cleavage under industrially preferred 450 nm excitation. As a proof of concept, the ion-pair complex was utilised to facilitate the trifluoromethylative difunctionalisation of diverse alkenes. This method yields pharmaceutically significant compounds and natural products with moderate to high yields. Both DFT calculations and experimental results demonstrate the formation of an ion-pairing complex, with binding constants K a of 4.36 in acetonitrile and 2.28 in chloroform, the latter increasing to 4.20 upon the addition of KOAc. This methodology exhibits substantial potential for future applications within biological and biochemical contexts.
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BibTeX
@misc{wang2026ionpair,
title = {{An Ion-Pair Complex-Enabled Photoinduced Cleavage of the Trifluoromethyl Thianthrenium Salt}},
author = {Ling Wang and Huda Hassan Dasuki and Mustapha Musa and Xuelong Zhang and Jonathan P. Knowles and Mark A. Fox and Na Wu},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15009981/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009981/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - An Ion-Pair Complex-Enabled Photoinduced Cleavage of the Trifluoromethyl Thianthrenium Salt
AU - Ling Wang
AU - Huda Hassan Dasuki
AU - Mustapha Musa
AU - Xuelong Zhang
AU - Jonathan P. Knowles
AU - Mark A. Fox
AU - Na Wu
PY - 2026
DA - 2026/10/06
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009981/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009981/v1
AB - Trifluoromethyl thianthrenium salts represent valuable reagents in photocatalysis; however, their activation traditionally necessitates external one-electron donors, such as photocatalysts, electron-donor-acceptor complexes. Direct photoexcitation can proceed without exogenous one-electron donors, thereby circumventing the stringent redox potential constraints inherent in the ground and excited states of conventional photocatalytic systems. Such direct excitation facilitates a transition of substrates to an electronically excited state, promoting homolytic cleavage to release the CF 3 • radical. Nevertheless, this process typically requires near-ultraviolet excitation (390 nm) to attain the high-energy excited singlet state of the substrate. In this study, we report a pioneering strategy involving the design of an acid-base ternary ion-pair complex utilising trifluoromethyl thianthrenium salts. In contrast to conventional ion-pair complex catalysis, this methodology eliminates the requirement for a photocatalyst and bypasses the single electron transfer process. This conceptual advancement lowers the activation energy to the excited singlet state of TT-CF 3 OTf, enabling the generation of CF 3 • species via homolytic cleavage under industrially preferred 450 nm excitation. As a proof of concept, the ion-pair complex was utilised to facilitate the trifluoromethylative difunctionalisation of diverse alkenes. This method yields pharmaceutically significant compounds and natural products with moderate to high yields. Both DFT calculations and experimental results demonstrate the formation of an ion-pairing complex, with binding constants K a of 4.36 in acetonitrile and 2.28 in chloroform, the latter increasing to 4.20 upon the addition of KOAc. This methodology exhibits substantial potential for future applications within biological and biochemical contexts.
ER -