Oxathiirane

We describe the first preparation of the long sought after parent oxathiirane from sulfine through photochemical rearrangement with light at 313 ± 10 nm in an Ar-matrix at 11 K. Oxathiirane was characterized by the extraordinarily good agreement  of experimentally measured and CCSD(T)/cc-pVTZ  (unscaled) computed vibrational frequencies both for the perhydrogenated and perdeuterated species.  The title molecule is about 10 kcal mol^–1 less stable than sulfine, in marked contrast to the isomer energy difference of dioxirane vs. carbonyl oxide (ca. –25 kcal mol^–1).  This is due to the strong positive polarization (blue potential) vs. the highly electronegative oxygen atom (red).  The stability ordering and the relative energy differences of carbonyl vs. thiocarbonyl groups underlines the likely role oxathiiranes play in sulfur transfer reactions.