trisilane
{{Chembox
| ImageFileL1 = Trisilane-2D-A.png
| ImageNameL1 = Stereo structural formula of trisilane with implicit hydrogens
| ImageFileR1 = Trisilane-MP2-CM-3D-balls.png
| ImageNameR1 = Ball and stick model of trisilane
| IUPACName = Trisilane
|Section1={{Chembox Identifiers
| CASNo = 7783-26-8
| CASNo_Ref = {{cascite|correct|??}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 1T3A75Z4ZL
| ChemSpiderID = 122661
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| EC_number = 616-514-9
| PubChem = 139070
| UNNumber = 3194
| SMILES = [SiH3] [SiH2] [SiH3]
| StdInChI = 1S/H8Si3/c1-3-2/h3H2,1-2H3
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = VEDJZFSRVVQBIL-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}}}
|Section2={{Chembox Properties
| H=8 | Si=3
| Appearance = Colourless liquid
| Odor = Unpleasant
| Density = 0.743 g cm−3
| MeltingPtC = -117
| BoilingPtC = 53
| Solubility = Slowly decomposes{{cite book |author1=Alfred Walter Stewart |title=Recent Advances in Physical and Inorganic Chemistry |date=1926 |publisher=Longmans, Green and Company, Limited |pages=312 |url=https://books.google.com/books?id=o3MVAQAAIAAJ |access-date=11 May 2021 |language=English}}
| VaporPressure = 12.7 kPa}}
|Section3={{Chembox Hazards
| MainHazards = Pyrophoric
| GHSPictograms = {{GHS02}}{{GHS07}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|250|261|315|319|335}}
| PPhrases = {{P-phrases|210|222|231+232|261|264|271|280|302+334|302+352|304+340|305+351+338|312|321|332+313|337+313|362|370+378|402+404|403+233|405|422|501}}
| FlashPt= <
| FlashPtC = -40
| AutoignitionPt = <
| AutoignitionPtC = 50
}}
|Section4={{Chembox Related
| OtherFunction_label = hydrosilicons
| OtherFunction = Disilane
Disilyne
Silane
Silylene
| OtherCompounds = Propane}}
}}
Trisilane is the silane with the formula H2Si(SiH3)2. A liquid at standard temperature and pressure, it is a silicon analogue of propane. In contrast with propane, however, trisilane ignites spontaneously in air.{{cite book|author=P. W. Schenk|chapter=Silanes|title=Handbook of Preparative Inorganic Chemistry, 2nd Ed. |editor=G. Brauer|publisher=Academic Press|year=1963|place=NY, NY|volume=1|pages=680}}
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Synthesis
Trisilane was characterized by Alfred Stock having prepared it by the reaction of hydrochloric acid and magnesium silicide.{{cite journal |doi=10.1002/cber.19160490114|title=Siliciumwasserstoffe. I. Die aus Magnesiumsilicid und Säuren entstehenden Siliciumwasserstoffe|year=1916|last1=Stock|first1=Alfred|last2=Somieski|first2=Carl|journal=Berichte der Deutschen Chemischen Gesellschaft|volume=49|pages=111–157|url=https://zenodo.org/record/1426597}}{{cite journal |doi=10.1002/cber.19230560735|title=Siliciumwasserstoffe, XVI.: Die höheren Siliciumhydride|year=1923|last1=Stock|first1=Alfred|last2=Stiebeler|first2=Paul|last3=Zeidler|first3=Friedrich|journal=Berichte der Deutschen Chemischen Gesellschaft (A and B Series)|volume=56|issue=7|pages=1695–1705}} This reaction had been explored as early as 1857 by Friedrich Woehler and Heinrich Buff, and further investigated by Henri Moissan and Samuel Smiles in 1902.
Decomposition
The key property of trisilane is its thermal lability. It degrades to silicon films and SiH4 according to this idealized equation:
:Si3H8 → Si + 2 SiH4
In terms of mechanism, this decomposition proceeds by a 1,2 hydrogen shift that produces disilanes, normal and isotetrasilanes, and normal and isopentasilanes.{{cite journal |doi=10.1021/ja00838a008|title=Kinetics of the thermal decomposition of methyldisilane and trisilane|year=1975|last1=Vanderwielen|first1=A. J.|last2=Ring|first2=M. A.|last3=O'Neal|first3=H. E.|journal=Journal of the American Chemical Society|volume=97|issue=5|pages=993–998}}
Because it readily decomposes to leave films of Si, trisilane has been explored a means to apply thin layers of silicon for semiconductors and similar applications.United States Patent Application Publication. Pub No. US 2012/0252190 A1, OCT, 4, 2012. Zehavi et al. Similarly, thermolysis of trisilane gives silicon nanowires.{{cite journal |doi=10.1021/ja8011353|title=Solution−Liquid−Solid (SLS) Growth of Silicon Nanowires|year=2008|last1=Heitsch|first1=Andrew T.|last2=Fanfair|first2=Dayne D.|last3=Tuan|first3=Hsing-Yu|last4=Korgel|first4=Brian A.|journal=Journal of the American Chemical Society|volume=130|issue=16|pages=5436–5437|pmid=18373344}}