Trisilane Explained

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.^[1]

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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 SiH₄In 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]

Notes and References

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