![]() Simplest silylene has R=Hydrogen | |
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Names | |
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IUPAC name Silylene | |
Systematic IUPAC name Silylidene [1] | |
Other names Hydrogen silicide(−II) Silicene | |
Identifiers | |
3D model (JSmol) | |
ChemSpider | |
PubChem CID | |
CompTox Dashboard (EPA) | |
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Properties | |
H2Si | |
Molar mass | 30.101 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Silylene is a chemical compound with the formula SiR2. It is the silicon analog of carbene. Silylene rapidly when condensed.
Silylenes are formal derivatives of silylene with its hydrogens replaced by other substituents. [2] Most examples feature amido (NR2) or organyl groups. [3] [4]
Silylenes have been proposed as reactive intermediates. They are carbene analogs. [5]
Silylenes have been generated by thermolysis or photolysis of polysilanes, by silicon atom reactions (insertion, addition or abstraction), by pyrolysis of silanes, or by reduction of 1,1-dihalosilane. It has long been assumed that the conversion of metallic Si to tetravalent silicon compounds proceeds via silylene intermediates:
Similar considerations apply to the direct process, the reaction of methyl chloride and bulk silicon.
Early observations of silylenes involved generation of dimethylsilylene by dechlorination of dimethyldichlorosilane: [6]
The formation of dimethylsilylene was demonstrated by conducting the dechlorination in the presence of trimethylsilane: the trapped product being pentamethyldisilane:
A room-temperature isolable N-heterocyclic silylene is N,N′-di-tert-butyl-1,3-diaza-2-silacyclopent-4-en-2-ylidene: [7]
The α-amido centers stabilize silylenes by π-donation. The dehalogenation of diorganosilicon dihalides is a widely exploited. [8]
In one study diphenylsilylene is generated by flash photolysis of a trisilane: [9]
In this reaction diphenylsilylene is extruded from the trisila ring. The silylene can be observed with UV spectroscopy at 520 nm and is short-lived with a chemical half-life of two microseconds. Added methanol acts as a chemical trap with a second order rate constant of 1.3×1010 mol−1 s−1 which is close to diffusion control.