Chlorotrifluorosilane

Chlorotrifluorosilane is an organic gaseous compound with formula SiClF3 composed of silicon, fluorine and chlorine. It is a silane that substitutes hydrogen with fluorine and chlorine atoms.

Chlorotrifluorosilane
Names
IUPAC name
chloro(trifluoro)silane[1]
Systematic IUPAC name
Chlorotrifluorosilane
Other names
silicon chlorotrifluoride[2]
Identifiers
3D model (JSmol)
ChemSpider
Properties
ClF3Si
Molar mass 120.53371
Appearance colorless gas
Density 1.31 g/mL
Melting point −138 °C (−216 °F; 135 K)
Boiling point critical point 303.7 K at 3.46 MPa
reacts
Vapor pressure 16600
1.279
Structure
distorted tetrahedron
0.636 D(gas)
Related compounds
Related compounds
 tetrafluorosilane
dichlorodifluorosilane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N (what is YN ?)
Infobox references

Production

By heating a mixture of anhydrous aluminium chloride and sodium hexafluorosilicate to between 190 and 250°C a mixture of gases containing chlorotrifluorosilane is given off. These are condensed at -196°C degrees and fractionally distilled at temperatures up to -78°C.[3]

SiClF3 can be made by reacting silicon tetrachloride and silicon tetrafluoride gases at 600°C, producing a mixture of fluorochloro silanes including about one quarter SiClF3.[4]

SiClF3 can be made by reacting silicon tetrachloride with antimony trifluoride. An antimony pentachloride catalyst assists. The products are distilled to separate it out from tetrafluorosilane and dichlorodifluorosilane.[5][6][7]

At high temperatures above 500°C silicon tetrafluoride can react with phosphorus trichloride to yield some SiClF3. This is unusual because SiF4 is very stable.[8]

Silicon tetrachloride can react with trifluoro(trichloromethyl)silane to yield SiClF3 and CCl3SiCl3.[9]

2-Chloroethyltrifluorosilane or 1,2-dichloroethyltrifluorosilane can be disassociated by an infrared laser to yield SiClF3 and C2H4 (ethylene) or vinyl chloride. By tuning the laser to a vibration frequency of a particular isotope of silicon, different isotomers can be selectively broken up in order to have a product that only concentrates one isotope of silicon. So silicon-30 can be increased to 80% by using the 934.5 cm−1 line in a CO2 laser.[10]

The first published preparation of SiClF3 by Schumb and Gamble was by exploding hexafluorodisilane in chlorine: Si2F6 + Cl2 → 2SiClF3. Other products of this explosion may include amorphous silicon, SiCl2F2 and SiF4.[11]

Chlorine reacts with silicon tetrafluoride in the presence of aluminium chips at 500-600°C to make mostly silicon tetra chloride and some SiClF3.[12]

Mercuric chloride when heated with SiF3Co(CO)4 breaks the bond to form a 90% yield of SiClF3.[13]

The combination of SiF4 and dimethylchlorophosphine and yield some SiClF3.[14]

Trifluorosilane SiHF3 reacts with gaseous chlorine to yield SiClF3 and HCl.[15]

Properties

Molecular size and angles

Bond length for Si–Cl is 1.996 Å and for Si–F is 1.558 Å. The bond angle ∠FSiCl = 110.2° and ∠FSiF = 108.7°.[5] The bond length between silicon and chlorine is unusually short, indicating a 31% double bond. This can be explained by the more ionic fluoride bonds withdrawing some charge allowing a partial positive charge on the chlorine.[16]

The molecular dipole moment is 0.636 Debye.[5]

Bulk properties

Between 129.18 and 308.83 K the vapour pressure in mm Hg at temperature T in K is given by log10 P = 102.6712 -2541.6/T -43.347 log10 T + 0.071921T -0.000045231 T2.[17]

The heat of formation of chlorotrifluorosilane is -315.0 kcal/mol at 298K.[18]

Reactions

Chlorotrifluorosilane is hydrolysed by water to produce silica.

Chlorotrifluorosilane reacts with trimethylstannane ((CH3)3SnH) at room temperature to make trifluorosilane in about 60 hours.[19]

Use

Proposed uses include a dielectric gas with a high breakdown voltage, and low global warming potential, a precursor for making fluorinated silica soot, and a vapour deposition gas.

Chlorotrifluorosilane can form an addition compound with pyridine with formula SiClF3.2py (py=pyridine) [20] An addition compound with trimethylamine exists.[21][22] This addition compound is made by mixing trimethylamine vapour with Chlorotrifluorosilane and condensing out a solid at -78°C. If this was allowed to soak in trimethylamine liquid for over eight hours, a diamine complex formed (2Me3N·SiClF3).[22] At 0° the disassociation pressure of the monoamine complex was 23 mm Hg.[22]

SiClF3− is a trigonal bipyramidal shape with a Cl and F atom on the axis. It is formed when gamma rays hit the neutral molecule.[23]

Chlorotetrafluorosilicate (IV) (SiClF4−) can form a stable a pale yellow crystalline compound tetraethylammonium tlorotetrafluorosilicate.[24]

References
  1. CID 139671 from PubChem
  2. Inorganic Syntheses, Inc (22 September 2009). Inorganic Syntheses. p. 266. ISBN 9780470132654.
  3. Schmeißer und Herber t Jenkne r, Martin; Jenkner, Herbert (1952). "Zurr Kenntnis anorganischer Säurefluoride (i) Über Reaktione n des Siliciumtetrafluorids (bzw. des Natriumsilicofluorids )" (PDF). Verlag Zeitschrift für Naturforschung: 191–192. doi:10.1515/znb-1952-0310. S2CID 95929863.
  4. US 2395826, Hill, Julian W. & Lindsey Jr. V, Richard, "Preparation of chlorofluorosilanes", issued 3 May 1946
  5. Cox, A.P.; Gayton, T.R.; Rego, C.A. (November 1988). "Microwave spectrum, structure, quadrupole coupling constant and dipole moment of chlorotrifluorosilane and iodotrifluorosilane". Journal of Molecular Structure. 190: 419–434. Bibcode:1988JMoSt.190..419C. doi:10.1016/0022-2860(88)80301-6.
  6. Booth, Harold Simmons; Swinehart, Carl F. (July 1935). "The Fluorochlorosilanes". Journal of the American Chemical Society. 57 (7): 1333–1337. doi:10.1021/ja01310a050.
  7. Annual Reports on the Progress of Chemistry. 1940. p. 151.
  8. Suresh, B.S.; Padma, D.K. (September 1985). "Halogen exchange reactions of silicon tetrafluoride with phosphorus trichloride and phosphoryl chloride". Journal of Fluorine Chemistry. 29 (4): 463–466. doi:10.1016/S0022-1139(00)85111-8.
  9. Weidenbruch, Manfred; Pierrard, Claude (April 1977). "Reaktionen von Halogeniden des Siliciums, Germaniums und Zinns mit Diazomethan und Dichlorcarben- Transfer-Agentien". Chemische Berichte (in German). 110 (4): 1545–1554. doi:10.1002/cber.19771100437.
  10. Dementyev, Petr S.; Nizovtsev, Anton S.; Chesnokov, Evgenii N. (July 2011). "Infrared photoreaction of 2-chloroethyltrifluorosilane". Journal of Photochemistry and Photobiology A: Chemistry. 222 (1): 77–80. doi:10.1016/j.jphotochem.2011.05.004.
  11. Schumb, Walter C.; Gamble, E. Lee (October 1932). "Fluorochlorides of Silicon". Journal of the American Chemical Society. 54 (10): 3943–3949. doi:10.1021/ja01349a018.
  12. Zuckerman, J. J (17 September 2009). Inorganic Reactions and Methods, the Formation of Bonds to Halogens. p. 361. ISBN 9780470145388.
  13. Zhou, Yong (3 September 2013). Organosilicon Chemistry: 2: Plenary Lectures Presented at the Second International Symposium on Organosilicon Chemistry. p. 443. ISBN 9781483284828.
  14. Journal of the Chinese Chemical Society. 1999. p. 450.
  15. Gmelin, Leopold (1996). Silicon: Supplement volume. p. 103. ISBN 9783540937289.
  16. Pauling, Linus (January 1960). The Nature of the Chemical Bond and the Structure of Molecules and Crystals: An Introduction to Modern Structural Chemistry. Cornell University Press. p. 312. ISBN 0801403332.
  17. Yaws, Carl L.; Nijhawan, Sachin; Bu, Li (1995). "Appendix C Coefficients for vapor pressure equation". Handbook of Vapor Pressure. 4. pp. 352–357. doi:10.1016/S1874-8813(06)80008-9. ISBN 9780884153948.
  18. Gordon, M. S.; Francisco, J. S.; Schlegel, H. B. (1993). "THEORETICAL INVESTIGATIONS OF THE THERMOCHEMISTRY AND THERMAL DECOMPOSITION OF SILANES, HALOSILANES, AND ALKYLSILANES" (PDF). Advances in Silicon Chemistry. JAI Press. 2: 153.
  19. Gmelin, Leopold (1996). Silicon: Supplement volume. p. 83. ISBN 9783540937289.
  20. Hensen, Karl; Wagner, Hans Bernhard (February 1976). "Über einige Verbindungen gemischter Siliciumhalogenide mit Pyridin". Chemische Berichte (in German). 109 (2): 411–414. doi:10.1002/cber.19761090201.
  21. Sommer, Leo Harry (1965). Stereochemistry, mechanism and silicon: An introduction to the dynamic stereochemistry and reaction mechanisms of silicon centers. McGraw-Hill. pp. 19–20.
  22. Fergusson, J. E.; Grant, D. K.; Hickford, R. H.; Wilkins, C. J. (1959). "21. Co-ordination of trimethylamine by halides of silicon, germanium, and tin". Journal of the Chemical Society (Resumed): 99–103. doi:10.1039/JR9590000099.
  23. Hasegawa, Akinori; Uchimura, Schunichiro; Koseki, Kohji; Hayashi, Michiro (January 1978). "ESR spectrum and structure of the SiF3Cl− radical anion". Chemical Physics Letters. 53 (2): 337–340. Bibcode:1978CPL....53..337H. doi:10.1016/0009-2614(78)85410-4.
  24. Edwards, H.G.M.; Fawcett, V.; Rose, S.J.; Smith, D.N. (May 1992). "The preparation and Raman spectroscopic study of the chlorotetrafluorosilicate (IV) ion, SiF4Cl−". Journal of Molecular Structure. 268 (4): 353–361. Bibcode:1992JMoSt.268..353E. doi:10.1016/0022-2860(92)80222-4.

Extra reading
  • Wodarczyk, F.J; Wilson, E.B (March 1971). "Radio frequency-microwave double resonance as a tool in the analysis of microwave spectra". Journal of Molecular Spectroscopy. 37 (3): 445–463. Bibcode:1971JMoSp..37..445W. doi:10.1016/0022-2852(71)90176-7.
  • Sheridan, John; Gordy, Walter (March 1950). "Microwave Spectra and Molecular Constants of Trifluorosilane Derivatives. SiF3H, SiF3CH3, SiF3Cl, and SiF3Br". Physical Review. 77 (5): 719. Bibcode:1950PhRv...77..719S. doi:10.1103/PhysRev.77.719.
  • Sheridan, John; Gordy, Walter (1951). "The Microwave Spectra and Molecular Structures of Trifluorosilane Derivatives". The Journal of Chemical Physics. 19 (7): 965. Bibcode:1951JChPh..19..965S. doi:10.1063/1.1748418.
  • Ault, Bruce S. (December 1979). "Infrared matrix isolation studies of the M+SiF5- ion pair and its chlorine-fluorine analogs". Inorganic Chemistry. 18 (12): 3339–3343. doi:10.1021/ic50202a012.
  • Stanton, C. T.; McKenzie, S. M.; Sardella, D. J.; Levy, R. G.; Davidovits, Paul (August 1988). "Boron atom reactions with silicon and germanium tetrahalides". The Journal of Physical Chemistry. 92 (16): 4658–4662. doi:10.1021/j100327a020.
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