Capture of the Sulfur Monoxide–Hydroxyl Radical Complex (•OH···OS)

The elusive hydrogen-bonded sulfur monoxide–hydroxyl radical complex (•OH···OS), a missing intermediate in the atmospheric chemistry of sulfur dioxide, has been generated in the 266 nm laser photolysis of the atmospheric relevant sulfinyl radical HOSO• in cryogenic Ar-matrices. In addition to the IR spectroscopic characterization with deuteration, its thermal conversion to HOSO• with an activation barrier of 0.330.11 kcal mol–1 (cal. 0.32 kcal mol–1, CCSD(T)-F12a/AVTZ) in the temperature range of 15.0–21.0 K and a H/D kinetic isotope effect (KIE) of 2.4 at 16.0 K have been observed.