Silylene dichlorosilylene

Inorganic Silylenes. Chemistry of Silylene, Dichlorosilylene, and Difluorosilylene... 

INORGANIC SILYLENES. CHEMISTRY OF SILYLENE, DICHLOROSILYLENE, AND DIFLUOROSILYLENE... 

Stable silylene complexes with halogen substituents are a useful starting material for further displacement reactions. Starting from 7 and 11, the Si complexes 22-24 are accessible in high yield. However, the intermediate dichlorosilylene complex... 

With dichlorosilylene, similar products result along with smaller amounts of the 2-silaindane. These are thought to result from insertion, or addition, of the silylene to the bicyclo valence isomer (11) of cyclooctatetraene (Scheme 24) (75ZOB2221), although a similar route to that in Scheme 23 is also possible. 

In view of the well-established silirane diradical mechanism in reactions of silylene [Eq. (10)] and dimethylsilylene 40, 62), and the involvement of difluorosilirane in the gas-phase reaction of difluoro-silylene [Eq. (61), Section IV], it is somewhat surprising to find that dichlorosilylene alone should take a concerted 1,4-addition route toward butadiene. Further studies are needed to settle this argument. 

Summary Starting with poiy(dichlorosilyiene-co-methylene) the synthesis of new poly(di-alky silylene-co-methylenes), poly(dialkenylsilylene-co-methylenes), and poly(dialkinylsilyl-ene-co-methylenes) was achieved by Grignaid or organolithium reactions. Furthermore poly(dichlorosilylene-co-methylene) was photochlorinated under UV irradiation to poly-(dichlorosilylene-co-dichloromethylene). 

Almost all silylenes or low-valent silicon compounds reported to date were prepared by reductions of their parent compounds using strong reducing agents, such as potassium metal or KCs-The synthesis of the first base-stabilized dichlorosilylene that is stable at room temperature (27), L SiCl2 is shown in Scheme 19.2. 

NHC-stabilized dichlorosilylene was shown to exhibit similar behavior in oxidative addition reactions (Scheme 16), i.e., formation of a SiOC three-membered heterocycle upon addition of benzophenone (74), whereas in the reaction withbenzil, the formation of a five-membered heterocycle is favored (75) [110]. The reaction with diphenylacetylene involves silylene oligomerization to also yield a compound with five-membered silacycle (76) [109]. 

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