1.1- Bis trimethylsilane

Several aromatic acyl silanes and the fascinating but unstable pink carbonyl bis(trimethylsilane) have been prepared in reasonably good yields by the oxidation of phosphonium ylids (Scheme 17)13. 

Remarkably, carbonyl bis(trimethylsilane) can act as a source of the CO2- dianion in the presence of fluoride ion (Scheme 82)13. 

A 100-g (588-mmol) sample of bis(trimethylsilyl)acetylene (1,2-ethynediyl-bis(trimethylsilane)) [(CH3)3SiC Si(CH3)3] is placed into a 500-mL flask fitted with a Teflon stopcock and degassed on a vacuum line. No further purification is necessary. The pentaborane(9) BjHst is used as received. 

The same chain transfer reactirai scheme can be applied to other styrene derivatives that contain a desirable functional group, such as Cl, OH, and NH2. Three functionalized styrenic chain transfer agents (St-f) were investigated p-chlorostyrene (St-Q), dimethylisopropylsilane protected p-vinylphenol (St-OSi), and bis(trimethylsilane) protected p-ethylaminostyrene (St-NSi2), as illustrated in Scheme 9, to prepare PP-t-St-Cl, PP-i-St-OH, and PP-i-St-NH2 polymers with a terminal functional group [58]. 

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