Schematic Design of Metal-Free NHC-Mediated Sequestering and Complete Conversion of SO 2 to Thiocarbonyl S -Oxide Derivatives at Room Temperature.

The sequestering and complete conversion of SO 2 to valuable chemicals in a metal-free pathway is highly demanded. The recent success of SO 2 fixation by N-heterocyclic carbenes instigated further studies in this regard. Previous reports were confined within the carbene-SO 2 reaction mechanism and the stability of oxathiirane S -oxide derivatives. The complete conversion of captured SO 2 to precious chemicals was not studied. The present inquisition has accomplished the scarcity of the earlier studies. It is observed that in the presence of an excess amount of carbene, the registered SO 2 is converted to the ketone derivative and thiocarbonyl S -oxide derivative. An electronic level investigation of these reactions is carried out. From the change of the molecular orbitals along the reaction path, it is concluded that the reaction between the oxathiirane S -oxide derivative and carbene follows a frog's hunting mechanism.