Bonding of Silylene Complexes

The first well-characterized silylene complexes stabilized by Lewis bases were reported by Zybill (Equation 13.36) and Tilley (Equation 13.37). In one case, the silylene complex was formed by elimination of a salt and in another case by abstraction of triflate in the presence of Lewis base. The first base-free silylene complexes were prepared by using soft iT-donating thiolate substituents on silicon (Equation 13.38). One thiolate group from a tris(thiolatosilyl) complex was abstracted with TMSOTf, and exchange of a less coordinating tetraphenylborate anion for triflate formed a stable cationic silylene product lacking coordinated base.  

Silylene complexes have been prepared by coordination of free silylene, extrusion of dihydrogen from a dihydrosilane, a-hydrogen elimination from a hydrosilyl complex, extraction of hydride, halide, or pseudo-haUde from a metal-silyl complex, and photoextrusion of silylene from a disilanyl complex. Examples of these reactions are shown in Equations 13.39-13.45. 

Pt(PCy3)2 + (Me3Si)2SiMes2 T MeaSijT P (Cy3P)2=SiMes2 

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