Tellurium hexafluoride

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Tellurium hexafluoride
Structure and dimensions of the molecule Tellurium-hexafluoride-dimensions-2D.png
Structure and dimensions of the molecule
Ball-and-stick model of the molelcule Tellurium-hexafluoride-from-xtal-1992-3D-balls.png
Ball-and-stick model of the molelcule
Identifiers
3D model (JSmol)
ECHA InfoCard 100.029.115 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 232-027-0
PubChem CID
UNII
  • InChI=1S/F6Te/c1-7(2,3,4,5)6
  • F[Te](F)(F)(F)(F)F
Properties
TeF6
Molar mass 241.590 g/mol
Appearancecolorless gas
Odor repulsive
Density 0.0106 g/cm3 (-10 °C)
4.006 g/cm3 (-191 °C)
Melting point −38.9 °C (−38.0 °F; 234.2 K) [1]
Boiling point −37.6 °C (−35.7 °F; 235.6 K) [1]
decomposes
Vapor pressure >1 atm (20°C) [2]
−66.0·10−6 cm3/mol
1.0009
Structure
Orthorhombic, oP28
Pnma, No. 62
octahedral (Oh)
0
Thermochemistry
117.6 J/(mol K)
−1318 kJ/mol
Hazards
Lethal dose or concentration (LD, LC):
5 ppm (rat, 4 hr)
5 ppm (mouse, 1 hr)
5 ppm (rabbit, 4 hr)
5 ppm (guinea pig, 4 hr) [3]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 0.02 ppm (0.2 mg/m3) [2]
REL (Recommended)
TWA 0.02 ppm (0.2 mg/m3) [2]
IDLH (Immediate danger)
1 ppm [2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Tellurium hexafluoride is the inorganic compound of tellurium and fluorine with the chemical formula TeF6. It is a colorless, highly toxic gas with an unpleasant odor. [4]

Contents

Preparation

Tellurium hexafluoride can be prepared by treating tellurium with fluorine gas at 150 °C. [4] [5] It can also be prepared by fluorination of TeO3 with bromine trifluoride. Upon heating, TeF4 disproportionates to give TeF6 and Te.[ citation needed ]

Properties

Tellurium hexafluoride is a highly symmetric octahedral molecule. Its physical properties resemble those of the hexafluorides of sulfur and selenium. It is less volatile, however, due to the increase in polarizability. At temperatures below −38 °C, tellurium hexafluoride condenses to a volatile white solid.

Reactivity

Tellurium hexafluoride is much more chemically reactive than SF6. [6] For example, TeF6 slowly hydrolyzes to Te(OH)6:

TeF6 + 6 H2O → Te(OH)6 + 6 HF

Treatment of tellurium hexafluoride with tetramethylammonium fluoride (Me4NF) gives, sequentially, the hepta- and octafluorides:

TeF6 + Me4NF → Me4NTeF7
Me4NTeF7 + Me4NF → (Me4N)2TeF8

Further sources

References

  1. 1 2 CRC Handbook of Chemistry and Physics , 90. Auflage, CRC Press, Boca Raton, Florida, 2009, ISBN   978-1-4200-9084-0, Section 4, Physical Constants of Inorganic Compounds, p. 4-95.
  2. 1 2 3 4 NIOSH Pocket Guide to Chemical Hazards. "#0588". National Institute for Occupational Safety and Health (NIOSH).
  3. ↑ "Tellurium hexafluoride (as Te)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. 1 2 W. Kwasnik (1963). "Tellurium Hexafluoride". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 1. NY, NY: Academic Press. p. 180.
  5. ↑ Yost, Don M. (2007) [1939]. "Sulfur, Selenium, and Tellurium Hexafluorides". Inorganic Syntheses. Vol. 1. pp. 121–122. doi:10.1002/9780470132326.ch44. ISBN   978-0-470-13232-6.
  6. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN   978-0-08-037941-8.
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