A photoexcited halogen-bonded EDA complex of the thiophenolate anion with iodobenzene for C(sp)-H activation and thiolation.

Thiophenol was discovered to form an EDA complex with iodobenzene through halogen bonding interactions upon treatment with KOH. A direct photochemical thiolation of C(sp)-H bond-containing etheric, allylic, and benzylic substrates with thiophenol was developed. The reaction proceeded on the basis of the generation of a thiyl radical and aryl radical through single electron transfer between the photoexcited thiophenolate anion and aryl iodide EDA complex. Then a C(sp) centred-radical was formed by aryl radical-mediated hydrogen atom transfer and the thiolation products were delivered a radical-radical cross-coupling with the thiyl radical.