Tellurium hexafluoride

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Tellurium hexafluoride
Structure and dimensions of the molecule Ball-and-stick model of the molelcule
Identifiers
CAS number 7783-80-4 YesY
PubChem 24559
EC number 232-027-0
Jmol-3D images Image 1
Properties
Molecular 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)[1]
Boiling point −37.6 °C (−35.7 °F; 235.6 K)[1]
Solubility in water decomposes
Refractive index (nD) 1.0009
Structure
Crystal structure Orthorhombic, oP28
Space group Pnma, No. 62
Coordination
geometry
octahedral (Oh)
Dipole moment 0
Thermochemistry
Specific
heat capacity
C
117.6 J/(mol K)
Std enthalpy of
formation
ΔfHo298
-1318 kJ/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Tellurium hexafluoride is the oldest[clarification needed] known fluoride of tellurium. It is a colorless, highly toxic gas with an extremely unpleasant smell.

Preparation[edit]

Tellurium hexafluoride is most commonly prepared by passing fluorine gas over tellurium metal at 150 °C. Below this temperature a mixture of lower fluorides form, including tellurium tetrafluoride and ditellurium decafluoride. It can also be prepared by passing fluorine gas over TeO3 or indirectly by reacting TeO2 with SeF4 to produce TeF4 and then heating TeF4 in excess of 200 °C to make TeF6 and Te.

Properties[edit]

Tellurium hexafluoride is a highly symmetric octahedral molecule. Its physical properties resemble the sulfur and selenium analogs. It is less volatile, however, due to the increase in molecular weight. 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[edit]

Unlike the sulfur analog, tellurium hexafluoride is not chemically inert. This can be attributed to the larger atomic radius which can co-ordinate a maximum of eight atoms rather than six for sulfur and selenium which allows for nucleophilic attack. TeF6 is hydrolyzed in water to Te(OH)6 and reacts with Te below 200 °C.

References[edit]

  1. ^ 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.

Literature[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.
  • N.N. Greenwood and A. Earnshaw; Chemistry of the Elements, 2nd edition, Butterworth, UK, 1997.
  • 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.

External links[edit]