Chemistry:Tetrasilane

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Tetrasilane
Tetrasilan.svg
Tetrasilane-3D-vdW.png
Names
Other names
n-Tetrasilane
Identifiers
3D model (JSmol)
ChemSpider
EC Number
  • 616-515-4
UNII
Properties
H10Si4
Molar mass 122.420 g·mol−1
Appearance colourless liquid that self ignite in air[1]
Density 0.792 g·cm−3[2]
Melting point −89.9 °C[2]
Boiling point 108.1 °C[2]
reacts[1]
Hazards
GHS pictograms GHS02: Flammable
GHS Signal word Danger
H250
Related compounds
Related compounds
butane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Tetrasilane is a silane with the structure formula SiH3–(SiH2)2–SiH3. It is the silane analog of butane.

Preparation

Tetrasilane can be prepared by reacting magnesium silicide (Mg2Si) with acids like 20% phosphoric acid in 50–60 °C.[3]

[math]\displaystyle{ \mathrm{Mg_2Si + \ 4 H^+\ \longrightarrow \ Si_nH_{2n+2}} }[/math]

The reaction can produce silanes up to n=15. The reaction of magnesium silicide with 25% hydrochloric acid produces 40% monosilane, 30% disilane, 15% trisilane, 10% tetrasilane and 5% higher silanes.[4] The mixture can be separated by fractional distillation.

In addition, higher silanes can also be obtained by discharges monosilane:[3]

[math]\displaystyle{ \mathrm{SiH_4 \ \rightarrow \ SiH_2 \ + \ H_2} }[/math]
[math]\displaystyle{ \mathrm{SiH_2 \ + \ SiH_4 \rightarrow \ H_3Si{-}SiH_3} }[/math]
[math]\displaystyle{ \mathrm{SiH_2 \ + \ H_3Si{-}SiH_3 \rightarrow \ H_3Si{-}SiH_2{-}SiH_3} }[/math]
[math]\displaystyle{ \mathrm{SiH_2 \ + \ H_3Si{-}SiH_2{-}SiH_3 \rightarrow \ H_3Si{-}SiH_2{-}SiH_2{-}SiH_3} }[/math]

Properties

Tetrasilane is a colourless, pyrophoric liquid that has a disgusting odour. Even below 54 °C, it will still spontaneous combust.[1] It is even more unstable than trisilane, slowly decomposing at room temperature, releasing hydrogen and forming shorter chain silanes.[5]

Reactions

Photochemical disproportionation of tetrasilane will produce 3-silylpentasilane and disilane.[6]

[math]\displaystyle{ \mathrm{2 \ Si_4H_{10} \rightarrow \ Si_2H_6 \ + H_3Si{-}SiH(Si_2H_6)_2 } }[/math]

With the presence of aluminium chloride, heating tetrasilane in xylene will allow isomerization to isotetrasilane.[7]

[math]\displaystyle{ \mathrm{2 \ H_3Si{-}SiH_2{-}SiH_2{-}SiH_3 \longrightarrow \ H_3Si{-}SiH(SiH_3)_2 } }[/math]

References

  1. 1.0 1.1 1.2 Material Safety Data Sheet for Tetrasilane (Si4H10) (PDF-Datei)
  2. 2.0 2.1 2.2 Lide, D. R., ed (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. p. 81. ISBN 0-8493-0486-5. 
  3. 3.0 3.1 Ralf Steudel (2014) (in German), [[1], p. 294, at Google Books Chemie der Nichtmetalle: Synthesen - Strukturen - Bindung – Verwendung], De Gruyter, pp. 294–295, ISBN 978-3-11-030797-9, [2], p. 294, at Google Books 
  4. Egon Wiberg (2011) (in German), [[3], p. 320, at Google Books Lehrbuch der Anorganischen Chemie: Mit einem Anhang: Chemiegeschichte], Walter de Gruyter, pp. 319–320, ISBN 978-3-11-023832-7, [4], p. 320, at Google Books 
  5. Alfred Stock, Paul Stiebeler, Friedrich Zeidler (1923-07-04), "Siliciumwasserstoffe, XVI.: Die höheren Siliciumhydride" (in German), Berichte der Deutschen Chemischen Gesellschaft 56 (7): pp. 1695–1705, doi:10.1002/cber.19230560735 
  6. F. Fehér, I. Fischer (March 1976), "Beiträge zur Chemie des Siliciums und Germaniums, XXVIII. Die photochemische Disproportionierung von n-Tetrasilan, Darstellung und Eigenschaften von 3-Silylpentasilan" (in German), Zeitschrift für anorganische und allgemeine Chemie 421 (1): pp. 9–14, doi:10.1002/zaac.19764210103 
  7. Template:ZNaturforsch