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 Ar1 S- containing very bulky acylamino groups forming NH···S hydrogen bonds, the crystal of the intermediate, [Ar1 S-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 [Ar1 S-I-I]- , consistent with theoretical calculations.