Visible‐Light‐Promoted Reversible Sulfide/Iodide Exchange in Fluoroalkyl Sulfides Enabled by Electron Donor‐Acceptor Complex Formation

Abstract Catalyst‐free visible‐light‐mediated exchange of two photoredox active groups, a 4‐perfluoropyridinylthio group and an iodide group, attached to a fluorinated alkyl fragment is described. The reaction can be preparatively performed in both directions by appropriate choice of wavelength, solvent, and counterion. In the forward reaction, alkyl sulfide interacts with an iodide anion to give alkyl iodide and a thiolate anion, with the driving force provided by blue light (455 nm). In the backward process, fluorinated alkyl iodide interacts with the thiolate under violet light (400 nm). The reactions proceed through the formation of electron donor‐acceptor (EDA) complexes, which were observed by UV/Vis absorption or NMR spectroscopies. Evidence of the sulfur–iodide interaction was supported by X‐ray analysis.