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]

Silicon tetraiodide
Names
Other names
silicon tetraiodide
Tetraiodosilane
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.033.355
EC Number
  • 236-706-2
  • InChI=1S/I4Si/c1-5(2,3)4 checkY
    Key: CFTHARXEQHJSEH-UHFFFAOYSA-N checkY
  • InChI=1/I4Si/c1-5(2,3)4
    Key: CFTHARXEQHJSEH-UHFFFAOYAL
  • I[Si](I)(I)I
Properties
SiI4
Molar mass 535.7034 g/mol
Appearance white powder
Density 4.198 g/cm3
Melting point 120.5 °C (248.9 °F; 393.6 K)
Boiling point 287.4 °C (549.3 °F; 560.5 K)
reacts
Solubility in organic solvents soluble
Structure
tetrahedral
Hazards
GHS labelling:
GHS05: CorrosiveGHS06: ToxicGHS07: Exclamation markGHS08: Health hazard
Danger
H301, H311, H314, H317, H334, H360
P201, P202, P260, P261, P264, P270, P272, P280, P281, P285, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P304+P341, P305+P351+P338, P308+P313, P310, P312, P321, P322, P330, P333+P313, P342+P311, P361, P363, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
2
0
0
Related compounds
Other anions
 Silicon tetrafluoride
Silicon tetrachloride
Silicon tetrabromide
Other cations
 Carbon tetraiodide
Germanium tetraiodide
Tin(IV) iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Infobox references

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]

Si + I2 → SiI4

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
SiH4SiF4SiCl4SiBr4SiI4
b.p. (˚C)[5]-111.9-90.356.8155.0290.0
m.p. (˚C)[5]-185-95.0-68.85.0155.0
Si-X bond length (Å)>0.74 [6]1.552.022.202.43
Si-X bond energy (kJ/mol)[7]384582391310234

References
  1. Kolonits, Maria; Hargittai, Magdolna (1998). "Molecular Structure of Silicon Tetraiodide". Structural Chemistry. 9 (5): 349–352. doi:10.1023/A:1022462926682. S2CID 96658381.
  2. Banerjee, Chiranjib; Wade, Casey R.; Soulet, Axel; Jursich, Gregory; McAndrew, James; Belot, John A. (2006). "Direct syntheses and complete characterization of halide-free tetrakis(dialkylamino)silanes". Inorganic Chemistry Communications. 9 (7): 761. doi:10.1016/j.inoche.2006.04.027.
  3. P. W. Schenk (1963). "Silicon and Germanium". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 2page=689. NY,NY: Academic Press.
  4. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  5. Silicon Compounds, Silicon Halides. Collins, W.: Kirk-Othmer Encyclopedia of Chemical Technology; John Wiley & Sons, Inc, 2001.
  6. "What is the bond length of the H-H bond?". Answers.com.
  7. Ebsworth, E. A. V. In Volatile Silicon Compounds; Taube, H.; Maddock, A. G.; Inorganic Chemistry; Pergamon Press Book: New York, NY, 1963; Vol. 4.
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