Snapshot of Oxidation of Thiolate by Diiodine: Stabilization of Intermediate by NH···S Hydrogen Bonds

Ordinary thiolate (RS–) reacts with diiodine
(I2) to afford an intermediate sulfenyl iodide (RSI) by
releasing I–; RSI is readily converted to disulfide
(RSSR) by a disproportionation reaction. In the case of thiolate Ar1S– containing
very bulky acylamino groups forming NH···S hydrogen
bonds, the crystal of the intermediate, [Ar1S–I–I]−, was obtained
under usual conditions, and the structure was determined by X-ray
diffraction analysis. The results show that the intramolecular NH···S
hydrogen bonds stabilized the intermediate [Ar1S–I–I]−, consistent
with theoretical calculations.