Sulfoxide Carbon−Sulfur Bond Activation

The alkynylsulfoxide, TMSC⋮CSO(p-tolyl) (TMS = trimethylsilyl, tolyl = C6H4Me), undergoes reaction with (η5-C5H5)Co(PPh3)2 at room temperature to give the cobaltosulfoxide complex, (C5H5)Co(PPh3)(η-C⋮CTMS)[η1-(S)-SO(p-tolyl)], which was characterized by X-ray crystallography. Exposure of this cobaltosulfoxide complex to oxygen gas leads to the formation of the corresponding metallosulfone complex, (C5H5)Co(PPh3)(η1-C⋮CTMS)[η1-(S)-SO2(p-tolyl)], which was characterized by X-ray crystallography. Alternatively, in solution at room temperature, the metallosulfoxide is converted to a 1:4 mixture of the equatorial−equatorial and equatorial−axial bridging cobalt−thiolato dimers, {(C5H5)Co[μ-S(p-tolyl)]}2, respectively. The equatorial−equatorial isomer was characterized by X-ray crystallography.