Reactive intermediates in organosilicon chemistry

Till about 1978 not much was known about the reactive intermediates in organosilicon chemistry but after that an almost explosion has taken place and now the vast amount of literature has shown their importance in the synthetic organic chemistry and in a way they are more important than purely organic reactive intermediates like carbenes, benzynes or nitrenes. 

However, mention should be made of the use of a trimethylsilyl methyl acetal of dimethylketene as an initiator for addition polymerization " and characterization or detection of compounds with Si=Si or Si=C bonds or containing divalent silicon or interchanges between these species. The chemistry of reactive intermediates in organosilicon chemistry has been reviewed by Barton."... 

Reactive intermediates are species that are so kinetically unstable that they cannot be isolated or observed under normal conditions. In organic chemistry, the radicals (R3C ), carbanions (R3C ), carbocations (R3C ), and car-benes (R2C ) are the more-common intermediates. The area, and the resulting chemistry, is far richer in organosilicon chemistry, because many of the bonding situations that produce quite stable organic compounds are highly reactive when Si replaces C. 

Brook, A. G. Bassindale, A. R. In Organic Chemistry DeMayo, R, Ed. Academic New York, 1980 Vol. 2, Essay No. 9. This article is the only comprehensive review of organosilicon rearrangements and suffers only from being a bit dated and its total exclusion of the rearrangements of organosilicon reactive intermediates. 

Organosilicon chemistry has expanded its scope considerably in the last two decades. One of the most remarkable achievements is the progress which was made in the elucidation of the mechanisms in silicon chemistry, which now become comparable to those in carbon chemistry. The behavior of reactive intermediates such as silylenes, silyl radicals and silyl anions are well explored, although the chemistry of silyl cations is still controversial. Doubly-bonded silicon species are now well understood " but triply-bonded silicon is still elusive. 

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