Reactions with Phenyllithium and PhMgBr

Si-fluorinated C-chlorinated 1,3,5-trisilacyclohexanes react with PhMgBr making the following compounds accessible [125]. 

However, compound 308 results only from reaction with PhLi. Attempts to use the CCI2 group in these compounds in the construction of C-bridged carbosilanes have only been brought to the stage of pilot reactions. 

SiH2-CH2-SiH3, -CH2-SiH3 and H3Si-CCl2-SiHMe- 

The enhancement of Si—H substitution and Si—C cleavage due to the use of more polar solvents confirms that changes of polarization in the molecule determine the course of reaction. In carbosilanes such as (H3Si—CH2)2SiH2, partial charge 

The Si- and C-chlorinated derivatives differ from SiH-containing C-chlorinated compounds only through the Si—Cl group. Because the Si—Cl bond has a large electron density available for shielding of the Si atom, due to the increased C-chlorination a reduced polarization and reactivity of the Si—Cl bond is observed. Therefore the different behavior of SiH- and CCl-containing carbosilanes, as opposed to SiCl-and CCl-containing carbosilanes, can be understood. 

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