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]
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3D model (JSmol)
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| ECHA InfoCard | 100.029.115 | ||
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CompTox Dashboard (EPA)
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| Properties | |||
| TeF6 | |||
| Molar mass | 241.590 g/mol | ||
| Appearance | colorless 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)[2] | ||
| Boiling point | −37.6 °C (−35.7 °F; 235.6 K)[2] | ||
| decomposes | |||
| Vapor pressure | >1 atm (20°C)[1] | ||
| −66.0·10−6 cm3/mol | |||
Refractive index (nD)
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1.0009 | ||
| Structure | |||
| Orthorhombic, oP28 | |||
| Pnma, No. 62 | |||
| octahedral (Oh) | |||
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| Thermochemistry | |||
Heat capacity (C)
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117.6 J/(mol K) | ||
Std enthalpy of
formation (ΔfH⦵298) |
-1318 kJ/mol | ||
| Hazards | |||
| Lethal dose or concentration (LD, LC): | |||
LCLo (lowest published)
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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)
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TWA 0.02 ppm (0.2 mg/m3)[1] | ||
REL (Recommended)
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TWA 0.02 ppm (0.2 mg/m3)[1] | ||
IDLH (Immediate danger)
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1 ppm[1] | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Preparation
editTellurium 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
editTellurium 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.
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Ball-and-stick model of the crystal structure -
Space-filling model of the crystal structure
Reactivity
editTellurium 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
edit- W.C. Cooper, Tellurium, Van Nostrand Reinhold Company, New York, USA, 1971.
- K.W. Bagnall, The Chemistry of Selenium, Tellurium and Polonium, Elsevier Publishing, New York, 1966.
- R.T. Sanderson, Chemical Periodicity, Reinhold, New York, USA, 1960.
- F. A. Cotton, G. Wilkinson, C.A. Murillo, and M. Bochmann; Advanced Inorganic Chemistry, John Wiley & Sons, 1999.
- G.J. Hathaway, N.H. Proctor, Chemical Hazards of the Workplace, 5th edition, Wiley-Interscience, New Jersey, 2004.
References
edit- ^ a b c d NIOSH Pocket Guide to Chemical Hazards. "#0588". National Institute for Occupational Safety and Health (NIOSH).
- ^ a b 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.
- ^ "Tellurium hexafluoride (as Te)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
- ^ a b W. Kwasnik (1963). "Tellurium Hexafluoride". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 1. NY, NY: Academic Press. p. 180.
- ^ 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.
- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.