Types and Sources of 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 

Over the years a number of general synthetic pathways to silenes have been developed these have been employed by research groups to generate families of silenes closely related in structure. It seems useful to list the most common pathways, together with references, in Table I14-91 and then to comment on some of them in detail. 

The first evidence for the formation of silenes came from the thermolysis of silacyclobutanes, which resulted in a retro-[2+2] process leading to the silene Me2Si=CH2 and ethylene1  

Generally, only simple silenes having small groups (H, Me, CH2=CH) are obtained as transient species from the thermolysis of silacyclobutanes. In part this is due to the high temperatures (usually above 450°C) required for the ring cleavage. Substitution on the carbon atom adjacent to silicon in the ring can lead to carbon-substituted silenes. 1,3-Disilacyclobutanes do not readily revert to silenes under thermal conditions, but examples 

Generalized silene structure Method of synthesis Common substituents Reference 

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