Ionic Components and the Reactive Intermediate Stages

The carbenium cation —C and the carbeniate anion —C are always trivalent. 

The silaonium cations and the silicate anions always have a valence greater than four, 

The —and —C radicals are essential reaction intermediates in carbon chemistry, 

The latest review [14] includes the characteristics of silyl radicals —Si, and all the literture pertaining to them. I 

Silylenes, — i , are the silicon analogues of carbenes. Dimethylsilylene, (H3C)2Si , can be prepared thermally by heating certain appropriate compounds, e.g. hexamethyl silinane [15] (Eq. 1.9), substituted disilanes [16] (Eq. 1.10) or Diels-Alder adducts [17] (Eq. 1.11)  

---