Silylene

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title: "Silylene" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["inorganic-silicon-compounds", "free-radicals", "octet-deficient-functional-groups"] topic_path: "general/inorganic-silicon-compounds" source: "https://en.wikipedia.org/wiki/Silylene" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

|Name = generic silylene |Watchedfields = changed |ImageFile = Silylene.svg |ImageFile1 = Silylene-3D-vdW.png |ImageCaption = Simplest silylene has R=Hydrogen |verifiedrevid = 464391717 |IUPACName = Silylene |SystematicName = Silylidene |OtherNames = Hydrogen silicide(−II) Silicene |Section1 = {{Chembox Identifiers |CASNo = 13825-90-6 |PubChem = 6327230 |ChemSpiderID = 4885758 |ChemSpiderID_Ref = |SMILES = [SiH2] |StdInChI = 1S/H2Si/h1H2 |StdInChI_Ref = |StdInChIKey = XMIJDTGORVPYLW-UHFFFAOYSA-N |StdInChIKey_Ref = |Section2 = {{Chembox Properties | H = 2 | Si = 1

Silylene is a chemical compound with the formula SiR2 (R = H). It is the silicon analog of carbene. Silylenes decomposes rapidly when condensed.

Silylenes are formal derivatives of silylene with its hydrogens replaced by other substituents. Most examples feature amido (NR2) or organyl groups.

Silylenes have been proposed as reactive intermediates. They are carbene analogs.

Synthesis and properties

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: :Si + Cl2 → SiCl2 :SiCl2 + Cl2 → SiCl4 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: :SiCl2(CH3)2 + 2 K → Si(CH3)2 + 2 KCl The formation of dimethylsilylene was demonstrated by conducting the dechlorination in the presence of trimethylsilane: the trapped product being pentamethyldisilane: :Si(CH3)2 + HSi(CH3)3 → (CH3)2Si(H)−Si(CH3)3

A room-temperature isolable N-heterocyclic silylene is : ::figure[src="https://upload.wikimedia.org/wikipedia/commons/9/99/DenkSiR2.png" caption="Synthesis of an isolable silylene."] ::

The α-amido centers stabilize silylenes by π-donation. The dehalogenation of diorganosilicon dihalides is a widely exploited.

Related reactions

::figure[src="https://upload.wikimedia.org/wikipedia/commons/9/9a/Decamethylsilicocene.png" caption="pmid=17090011}}"] ::

:[[File:Diphenylsilylene.png|400px|Diphenylsilylene]]

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 which is close to diffusion control.

References

References

1. {{BlueBook2013
2. (2009). "Stable Heavier Carbene Analogues". Chemical Reviews.
3. (2008). "The Chemistry of Aluminum(I), Silicon(II), and Germanium(II)". Organometallics.
4. (2000). "Stable Silylenes". Accounts of Chemical Research.
5. (1998). "The Chemistry of Organic Silicon Compounds".
6. (1964). "Dimethylsilene: CH₃SiCH₃". Journal of the American Chemical Society.
7. (1994). "Synthesis and Structure of a Stable Silylene". Journal of the American Chemical Society.
8. (2006). "A New Type of ''N''-Heterocyclic Silylene with Ambivalent Reactivity". Journal of the American Chemical Society.
9. (2006). "Diphenylsilylene". Journal of the American Chemical Society.

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