Silicon tetraiodide
Silicon tetraiodide is the chemical compound with the formula SiI4. It is a tetrahedral molecule with Si-I bond lengths of 2.432(5) Å.[1]
SiI4 is a precursor to silicon amides of the formula Si(NR2)4 (R = alkyl).[2] It has also been of interest in the manufacture and etching of silicon in microelectronics.
Synthesis and reactions
This compound is produced by treating silicon-copper mixture with iodine:[3]
It reacts quickly with water and moisture in the air.
It can also be made on a large scale by reaction of silicon or silicon carbide with iodine on heating to about 200 °C. Of more academic interest is the reaction of silane with iodine vapour at 130 - 150 °C, as this produces a series of compounds ranging from iodosilane SiH3I to diiodosilane SiH2I2 and triiodosilane SiHI3 as well. These compounds are colourless liquids at room temperature.[4] The last one can be readily distinguished from the similar carbon compound, iodoform which is a yellow solid at room temperature.
Comparison with other SiX4 compounds
| SiH4 | SiF4 | SiCl4 | SiBr4 | SiI4 | |
|---|---|---|---|---|---|
| b.p. (˚C)[5] | −111.9 | −90.3 | 56.8 | 155.0 | 290.0 |
| m.p. (˚C)[5] | −185 | −95.0 | −68.8 | 5.0 | 155.0 |
| Si-X bond length (Å) | >0.74 [6] | 1.55 | 2.02 | 2.20 | 2.43 |
| Si-X bond energy (kJ/mol)[7] | 384 | 582 | 391 | 310 | 234 |
References
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- ↑ Template:Greenwood&Earnshaw
- ↑ a b Silicon Compounds, Silicon Halides. Collins, W.: Kirk-Othmer Encyclopedia of Chemical Technology; John Wiley & Sons, Inc, 2001.
- ↑ Script error: No such module "citation/CS1".
- ↑ Ebsworth, E. A. V. In Volatile Silicon Compounds; Taube, H.; Maddock, A. G.; Inorganic Chemistry; Pergamon Press Book: New York, NY, 1963; Vol. 4.
External links
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