Trisilane

Trisilane is the silane with the formula H2Si(SiH3)2. A liquid at standard temperature and pressure, it is a silicon analogue of propane. The contrast with propane however trisilane ignites spontaneously in air.[1]

Trisilane
Stereo structural formula of trisilane with implicit hydrogens
Ball and stick model of trisilane
Names
IUPAC name
Trisilane
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.132.113
UNII
UN number 3194
Properties
H8Si3
Molar mass 92.319 g·mol−1
Appearance Colourless liquid
Odor Unpleasant
Density 0.743 g cm−3
Melting point −117 °C (−179 °F; 156 K)
Boiling point 53 °C (127 °F; 326 K)
Vapor pressure 12.7 kPa
Hazards
Main hazards Pyrophoric
S-phrases (outdated) S3
Flash point < −40 °C (−40 °F; 233 K)
< 50 °C (122 °F; 323 K)
Related compounds
Related hydrosilicons
 Disilane
Disilyne
Silane
Silylene
Related compounds
 Propane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Synthesis

Trisilane was characterized by Alfred Stock having prepared it by the reaction of hydrochloric acid and magnesium silicide.[2][3] 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.[1]

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.[4]

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.[5] Similarly, thermolysis of trisilane gives silicon nanowires.[6]

References
  1. P. W. Schenk (1963). "Silanes". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. 1. NY, NY: Academic Press. p. 680.
  2. Stock, Alfred; Somieski, Carl (1916). "Siliciumwasserstoffe. I. Die aus Magnesiumsilicid und Säuren entstehenden Siliciumwasserstoffe". Berichte der Deutschen Chemischen Gesellschaft. 49: 111–157. doi:10.1002/cber.19160490114.
  3. Stock, Alfred; Stiebeler, Paul; Zeidler, Friedrich (1923). "Siliciumwasserstoffe, XVI.: Die höheren Siliciumhydride". Berichte der Deutschen Chemischen Gesellschaft (A and B Series). 56 (7): 1695–1705. doi:10.1002/cber.19230560735.
  4. Vanderwielen, A. J.; Ring, M. A.; O'Neal, H. E. (1975). "Kinetics of the thermal decomposition of methyldisilane and trisilane". Journal of the American Chemical Society. 97 (5): 993–998. doi:10.1021/ja00838a008.
  5. United States Patent Application Publication. Pub No. US 2012/0252190 A1, OCT, 4, 2012. Zehavi et al.
  6. Heitsch, Andrew T.; Fanfair, Dayne D.; Tuan, Hsing-Yu; Korgel, Brian A. (2008). "Solution−Liquid−Solid (SLS) Growth of Silicon Nanowires". Journal of the American Chemical Society. 130 (16): 5436–5437. doi:10.1021/ja8011353. PMID 18373344.
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