Carbon−Sulfur Bond Cleavage and Hydrodesulfurization of Thiophenes by Tungsten

The reactions of W(PMe3)4(η2-CH2PMe2)H, W(PMe3)5H2, W(PMe3)4H4 and W(PMe3)3H6 towards thiophenes reveal that molecular tungsten compounds are capable of achieving a variety of transformations that are relevant to hydrodesulfurization. For example, sequential treatment of W(PMe3)4(η2-CH2PMe2)H with thiophene and H2 yields the butanethiolate complex, W(PMe3)4(SBun)H3, which eliminates but-1-ene at 100 °C. Likewise, sequential treatment of W(PMe3)4(η2-CH2PMe2)H with benzothiophene and H2 yields W(PMe3)4(SC6H4Et)H3, which releases ethylbenzene at 100 °C. Moreover, W(PMe3)4(η2-CH2PMe2)H desulfurizes dibenzothiophene to form a dibenzometallacyclopentadiene complex, [(κ2-C12H8)W(PMe3)](μ-S)(μ-CH2PMe2)(μ-PMe2)[W(PMe3)3].