Oligosilanyl anions

The oligosilanyl anion chemistry was also used to change the substitution pattern of a cyclotetrasilane. Reaction of tetrakis(trimethylsilyl)cyclotetrasilane with f-BuOK led to the respective silyl potassium compotmds which further were reacted with suitable electrophiles (Scheme 9) [111]. 

In a comparable way as outlined below for lead, Klinkhammer and coworkers obtained a number of oligosilanylated stannyl anions and radicals by reaction of oligosilanyl anions with diamino and diaryloxy stannylenes [246]. Scheschkewitz and coworkers found that the reaction of a disilenyl lithium species with Me2SnCl2 gave a chlorinated disilastanniranes (9) [247]. 

Methods to attach oligosilanyl unity to other organic or inorganic molecular entities are mostly confined to reactions of silyl anions or halides depending on the nucleophilic or electrophilic nature of the other fragment. Especially for addition reactions to unsaturated molecules also silyl radicals or silyl hydrides are common reagents. 

Oligosilanyl halides are also very abundant and their treatment as a separate compound class would thus be too exhaustive. Silyl halides are of major importance for the generation of numerous silicon species. By reaction with nucleophiles including lithium alkyls, silyl anions, amines, amides, alcohols, and alkoxides, Si-X bonds are easily formed. They also serve as starting materials for Si-Si bond formation by Wurtz coupling or for the generation of unsaturated compounds such as disilenes, disilynes, or silylenes. 

While recent oligosilanyl zinc chemistry was studied by several research groups not much has been done with respect to cadmium. In contrast to this a large variety of oligosilanyl mercury compounds were studied almost exclusively by Apeloig and coworkers, who utilized the unique properties of Si-Hg compounds for the generation of silyl radicals or anions. 

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