Hydrogenation of SiCl- and CH-Containing Carbosilanes

The Si—Cl groups in CH -containing carbosilanes are converted to Si—H groups by hydrogenation with LiAlH without a change in the molecular skeleton [93, 94]. 

2 (Cl3Si)2CH2 + 3 UAIH4 - 2 (H3Si)2CH2 -f 3 AICI3 + 3 LiCl 

Pure (H3Si)2CH2 can be obtained in dibutylether in a yield higher than 80%. It has an extrapolated boiling point of 16.7 °C, is remarkably stable and is not self-igniting on contact with air. The same applies to (H3Si—CH2)2SiH2, formed as a colorless liquid (bp. 100 °C/760 mm Hg). 

The compound (H2Si—CH2)3 (bp. 142 °C/760 mm Hg) forms white crystals below 10 °C, with a yield greater than 80%. The formation of (H2Si—CH2)3 occurs only after addition of an excess of LiAlH4 otherwise a mixture of SiCl-containing compounds is obtained. 

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