Silylene

<h2 id="synthesis-and-properties">Synthesis and properties</h2>
Silylenes have been generated by <a href="/facts/Thermolysis/Qqx9RqkW">thermolysis</a> or <a href="/facts/Photolysis/nzRyzh8I">photolysis</a> of <a href="/facts/Polysilane/ctjIMTAw">polysilanes</a>, by <a href="/facts/Silicon/cgWx0hdr">silicon</a> atom reactions (<a href="/facts/Insertion_reaction/Mx600UYr">insertion</a>, <a href="/facts/Addition_reaction/LvIngK0g">addition</a> or abstraction), by <a href="/facts/Pyrolysis/h1cEegI7">pyrolysis</a> of <a href="/facts/Silane/XNevDLgE">silanes</a>, or by <a href="/facts/Redox/Pyd5RVcj">reduction</a> 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 <a href="/facts/Direct_process/wDu3X0bQ">direct process</a>, the reaction of <a href="/facts/Methyl_chloride/DvmeEgDS">methyl chloride</a> and bulk silicon.
Early observations of silylenes involved generation of dimethylsilylene by dechlorination of <a href="/facts/Dimethyldichlorosilane/V3rMdG5t">dimethyldichlorosilane</a>:<a class="footnote-ref" id="fnref:5" href="#fn:5">5</a>

SiCl2(CH3)2 + 2 K → Si(CH3)2 + 2 KCl
The formation of dimethylsilylene was demonstrated by conducting the dechlorination in the presence of <a href="/facts/Trimethylsilane/cgwLhNKs">trimethylsilane</a>: the <a href="/facts/Chemical_trap/NUoApMRS">trapped</a> product being pentamethyldisilane:

Si(CH3)2 + HSi(CH3)3 → (CH3)2Si(H)−Si(CH3)3
A room-temperature isolable <a href="/facts/N-heterocyclic_silylene/YSxSgC4t">N-heterocyclic silylene</a> is N,N′-di-tert-butyl-1,3-diaza-2-silacyclopent-4-en-2-ylidene:<a class="footnote-ref" id="fnref:6" href="#fn:6">6</a>

The α-amido centers stabilize silylenes by π-donation. The dehalogenation of diorganosilicon dihalides is a widely exploited.<a class="footnote-ref" id="fnref:7" href="#fn:7">7</a>

<h2 id="related-reactions">Related reactions</h2>
In one study diphenylsilylene is generated by <a href="/facts/Flash_photolysis/g9gSdAHr">flash photolysis</a> of a trisilane:<a class="footnote-ref" id="fnref:8" href="#fn:8">8</a>

In this reaction diphenylsilylene is extruded from the trisila ring. The silylene can be observed with <a href="/facts/UV_spectroscopy/MUPLLczo">UV spectroscopy</a> at 520 nm and is short-lived with a <a href="/facts/Chemical_half-life/kGVH8BAB">chemical half-life</a> of two <a href="/facts/Microsecond/zdW1DEb2">microseconds</a>. Added <a href="/facts/Methanol/EIfpoNCg">methanol</a> acts as a <a href="/facts/Chemical_trap/NUoApMRS">chemical trap</a> with a <a href="/facts/Second_order_rate_constant/VK18zUhN">second order rate constant</a> of 1.3×1010 mol−1 s−1 which is close to diffusion control.

<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Carbene_analogs/NGW1IozS">Carbene analogs</a></li>
<li><a href="/facts/N-heterocyclic_silylene/YSxSgC4t">N-heterocyclic silylene</a></li>
<li><a href="/facts/Silenes/mSr8aF2N">Silenes</a>, R2Si=SiR2</li>
<li><a href="/facts/Silylium_ion/YvGtpf5K">Silylium ions</a>, protonated silylenes</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1">Mizuhata, Yoshiyuki; Sasamori, Takahiro; Tokitoh, Norihiro (2009). "Stable Heavier Carbene Analogues". Chemical Reviews. 109 (8): 3479–3511. doi:10.1021/cr900093s. PMID 19630390. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></li>
<li id="fn:2">Nagendran, Selvarajan; Roesky, Herbert W. (2008). "The Chemistry of Aluminum(I), Silicon(II), and Germanium(II)". Organometallics. 27 (4): 457–492. doi:10.1021/om7007869. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></li>
<li id="fn:3">Haaf, Michael; Schmedake, Thomas A.; West, Robert (2000). "Stable Silylenes". Accounts of Chemical Research. 33 (10): 704–714. doi:10.1021/ar950192g. PMID 11041835. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></li>
<li id="fn:4">Gaspar, Peter; West, R. (1998). "Silylenes". The Chemistry of Organic Silicon Compounds. The Chemistry of Functional Groups. Vol. 2. pp. 2463–2568. doi:10.1002/0470857250.ch43. ISBN 0471967572. <a href="0471967572" target="_blank">0471967572</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></li>
<li id="fn:5">Skell, P. S.; Goldstein, E. J. (1964). "Dimethylsilene: CH3SiCH3". Journal of the American Chemical Society. 86 (7): 1442–1443. doi:10.1021/ja01061a040. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></li>
<li id="fn:6">Denk, Michael; Lennon, Robert; Hayashi, Randy; West, Robert; Belyakov, Alexander V.; Verne, Hans P.; Haaland, Arne; Wagner, Matthias; Metzler, Nils (1994). "Synthesis and Structure of a Stable Silylene". Journal of the American Chemical Society. 116 (6): 2691–2692. doi:10.1021/ja00085a088. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></li>
<li id="fn:7">Driess, Matthias; Yao, Shenglai; Brym, Markus; Van Wüllen, Christoph; Lentz, Dieter (2006). "A New Type of N-Heterocyclic Silylene with Ambivalent Reactivity". Journal of the American Chemical Society. 128 (30): 9628–9629. doi:10.1021/ja062928i. PMID 16866506. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></li>
<li id="fn:8">Moiseev, Andrey G.; Leigh, William J. (2006). "Diphenylsilylene". Journal of the American Chemical Society. 128 (45): 14442–14443. doi:10.1021/ja0653223. PMID 17090011. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></li>
</ol>

Silylene open-in-new

Silylene