Silicon-carbon compounds silenes

Silenes with a wide range of structures have been synthesized over the years, from the simplest possible compound, H2Si=CH2, which has a transient existence, to species that contain four complex groups attached to the ends of the silicon-carbon double bond, e.g., (Me3Si)MesSi=C... 

Silicon-carbon and silicon-nitrogen multiply bonded compounds 917 now gained acceptance as evidence for the intermediate formation of a transient silene. 

The first compelling evidence that a silene (a compound containing a silicon-carbon double bond) could exist was provided by Gusel nikov and Flowers in 1967 from results of the thermolysis of dimethylsilacyclobutane26 (equation 16). Thus, it is not surprising that... 

In Table 1 the structural data of the synthesized intramolecularly donor-stabilized silenes 10,11, 14 and 15 are summarized and additionally, for comparison, some data taken from the literature are given. The silicon-carbon distances, the silicon-nitrogen distances and the sums of angles at the silene silicon atoms as well as at the silene carbon atoms of the unsaturated siUcon compounds... 

Silicon-carbon and silicon-nitrogen mnltiply bonded compounds 969 Wiberg -type silenes which can be easily cleaved thermolytically to the silene and the... 

Since the isolation of the first example of a stable silene (1), compounds possessing silicon—carbon double bonds have been a focus of research because of their unique electronic properties and reactivities. However, the number of stable silenes remains very limited. Sila-Peterson reaction has proved to be a facile route toward the synthesis of stable silenes replacing photolysis and thermal treatments. 

Naka A, Ishikawa M (2000) Silicon-carbon unsaturated compounds. 62. Reactions of silenes produced thermally from pivaloyl- and adamantoyltris(trimethylsilyl)silane with mono(silyl) acetylenes. J Organomet Chem 611 248... 

The chemical shifts of jp3-hybridized silicon atoms, such as a trimethyl-silyl group attached to the jp2-hybridized silicon in silenes, are normally found from -10 to -18 ppm, as compared to the position at -9.8 ppm for the trimethylsilyl groups of (Me3Si)4Si (the central silicon atom of this compound resonates at -135.5 ppm). On the other hand, a trimethylsiloxy group attached to carbon, either sp2- or sp3-hybridized, normally absorbs in the range from +5 to +20 ppm. 

After decades of unsuccessful attempted syntheses, Gusel nikov and Flowers in 1967 reported the first compelling evidence for the existence of silenes, compounds containing a double bond between silicon and carbon. This initiated a renewed interest in the synthesis and behavior of stable silenes,8 disilenes,b iminosilanes,c phosphasilenesd and their heavier homologs. 

Considerable insight into the broader question of how the kinetic and thermodynamic stability of the Si=C bond is affected by substituents at silicon and carbon was obtained in the late 1970s, when Brook and coworkers reported the isolation and characterization of the first stable silene derivatives (80), prepared by photolysis of the corresponding acylpolysilanes (79) as shown in equation 6017. The unique stability of these compounds is clearly due to steric stabilization effects to some extent, but it was suggested that the siloxy substituent at carbon also reduces the reactivity of these silenes toward dimerization as a result of resonance effects on the degree of positive charge character at silicon. 

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