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Tellurium hexafluoride
Structure and dimensions of the molecule	Ball-and-stick model of the molelcule
Identifiers
CAS Number	7783-80-4 ;
3D model (JSmol)	Interactive image;
ECHA InfoCard	100.029.115
EC Number	232-027-0;
PubChem CID	24559;
UNII	JWI7143IXR ;
CompTox Dashboard (EPA)	DTXSID20893077 ;
	InChI InChI=1S/F6Te/c1-7(2,3,4,5)6;
	SMILES F[Te](F)(F)(F)(F)F;
Properties
Chemical formula	TeF6
Molar mass	241.590 g/mol
Appearance	colorless gas
Odor	repulsive odor
Density	0.0106 g/cm3 (-10 °C) ; 4.006 g/cm3 (-191 °C)
Melting point	−38.9 °C (−38.0 °F; 234.2 K)
Boiling point	−37.6 °C (−35.7 °F; 235.6 K)
Solubility in water	decomposes
Vapor pressure	>1 atm (20°C)
Magnetic susceptibility (χ)	−66.0·10−6 cm3/mol
Refractive index (nD)	1.0009
Structure
Crystal structure	Orthorhombic, oP28
Space group	Pnma, No. 62
Coordination geometry	octahedral (Oh)
Dipole moment	0
Thermochemistry
Heat capacity (C)	117.6 J/(mol K)
Std enthalpy of; formation (ΔfH⦵298)	-1318 kJ/mol
Hazards
	Lethal dose or concentration (LD, LC):
LCLo (lowest published)	5 ppm (rat, 4 hr); 5 ppm (mouse, 1 hr); 5 ppm (rabbit, 4 hr); 5 ppm (guinea pig, 4 hr)
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.02 ppm (0.2 mg/m3)
REL (Recommended)	TWA 0.02 ppm (0.2 mg/m3)
IDLH (Immediate danger)	1 ppm
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

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]

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.

Ball-and-stick model of the crystal structure
Space-filling model of the crystal structure

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

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

^ ^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.