Approach to the "Missing" Diarylsilylene: Formation, Characterization, and Intramolecular C-H Bond Activation of Blue Diarylsilylenes with Bulky Rind Groups.

The treatment of the bulky Rind-based dibromosilanes, (Rind)SiBr () [Rind = 1,1,7,7-tetra-R-3,3,5,5-tetra-R--hydrindacen-4-yl: EMind (: R = Et, R = Me) and Eind (: R = R = Et)], with two equivalents of BuLi in EtO at low temperatures resulted in the formation of blue solutions derived from the diarylsilylenes, (Rind)Si: (). Upon warming the solutions above -20 °C, the blue color gradually faded, accompanying the decomposition of and yielding cyclic hydrosilanes () via intramolecular C-H bond insertion at the Si(II) center. The molecular structures of the bulky Eind-based and were confirmed by X-ray crystallography.