Silylene insertion into

CHCI3. Similar 2 1 adducts were formed quantitatively when 122 was treated with CCl4, CH2CI2, or benzyl chloride.However, product 131 was obtained exclusively via silylene insertion into the C—Cl bond when 122 was allowed to react with tert-butyl chloride.It is proposed that the formation of 130 is a result of the initial halophihc interaction between the silylene and halocarbon. 

Disilanyl enol ethers (22) are the main product of the reaction of alkyl ketones with photochemically generated phenyltrimethylsilylsilylene (Scheme 30) (77JOM(135)C45). They could result from silylene insertion into the enol O—H bond, particularly as many have been isolated from dodecamethylcyclohexasilane and alkyl ketones or aldehydes on photolysis (Scheme 31) (78CL609). 

The first 1,2-disilacyclobutene (82) was prepared in 1973 by the gas phase reaction of dimethylsilylene and 2-butyne (73JOM(52)C21). It probably results through silylene insertion into the intermediate silacyclopropene (Section 1.20.3.4), but silylene dimerization followed by addition to the alkyne is also suggested (76JA7746), since (82) is formed in good yield if the disilene is generated directly (Scheme 127) (78JOM(162)C43). 

Insertion of SiH2 into H—H and H—C bonds, respectively, has been assumed in reports of rate constants from laser flash photolysis experiments for reactions of SiH2 with H2108 109, D2109 and CH4108. Since the rate of silylene insertion into the H—H bond was more rapid than previous estimates, interest was reawakened in the activation barrier112-114. The barrier for insertion of SiH2 into H2 was revised downward to ca 1 kcalmol-1. 

A bizarre silylene insertion into the I—I bond has been suggested as the initial step in the mechanism for the low-temperature (—90 °C) reaction of dihalosilylenes (SiF2, SiCl2, SiBr2) with solutions of iodine in toluene, as shown in equation 58125. These reactions can be considered to involve electrophilic attack on an arene by SiX2l+126. 

Silylene insertion into the Si H bond as well as silylene insertion into the Si Si bond forms new silicon-siliconbonds (equations 59 and 60). 

Silylene insertion into allylic ethers is of interest to synthesis because it changes an electrophilic unit into a nucleophilic unit. 

MesSi-SiH , generated in the gas-phase at 570 C in the presence of butadiene, the yields of products from an Me-shift forming Me2Si=SiHMe totaled 10 %, while silylene insertion into a C-H bond forming a disilirane intermediate led to products in 12% total yield, and trapping of unrearranged silylene led to products totaling 25 % yield [29]. 

Silylene insertion into the S—H bond of silanes has been reported. ... 

Silylenoids representing key intermediates in the direct synthesis should be stabilized on the surface by n-doping of the silicon. This means that a stronger donor quality of the silicon surface favors the more selective silylene insertion into the C-Cl bond of melhyl chloride in comparison with Si-Si bond formation via insertion into a Si-Cl bond or oligomerization of the silylenes. 

Scheme 25 Oligosilane fonnation by silylene insertion into Si-Cl bonds...

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