Tellurium hexafluoride is the
inorganic compound of
tellurium
Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionall ...
and
fluorine with the chemical formula TeF
6. It is a colorless, highly toxic gas with an unpleasant odor.
Preparation
Tellurium hexafluoride can be prepared by treating tellurium with
fluorine gas at 150 °C.
It can also be prepared by fluorination of
TeO3 with
bromine trifluoride
Bromine trifluoride is an interhalogen compound with the formula BrF3. At room temperature, it is a straw-coloured liquid with a pungent odor which decomposes violently on contact with water and organic compounds. It is a powerful fluorinating a ...
. Upon heating,
TeF4 disproportionates to give TeF
6 and Te.
Properties
Tellurium hexafluoride is a highly symmetric octahedral molecule. Its physical properties resemble those of the hexafluorides of
sulfur and
selenium
Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, ...
. It is less
volatile, however, due to the increase in
polarizability
Polarizability usually refers to the tendency of matter, when subjected to an electric field, to acquire an electric dipole moment in proportion to that applied field. It is a property of all matter, considering that matter is made up of elementar ...
. At temperatures below −38 °C, tellurium hexafluoride condenses to a volatile white solid.
File:Tellurium-hexafluoride-xtal-1992-3D-balls.png, Ball-and-stick model of the crystal structure
File:Tellurium-hexafluoride-xtal-1992-3D-SF.png, Space-filling model of the crystal structure
Reactivity
Unlike SF
6, tellurium hexafluoride is not chemically
inert.
For example, TeF
6 slowly hydrolyzes to
Te(OH)6:
:TeF
6 + 6 H
2O → Te(OH)
6 + 6 HF
Treatment of tellurium hexafluoride with
tetramethylammonium fluoride
Tetramethylammonium fluoride is the quaternary ammonium salt with the formula (CH3)4NF. This hygroscopic white solid is a source of “naked fluoride", that is fluoride ions not connected to a metal atom in a complex. Most other soluble salts of f ...
(Me
4NF) gives, sequentially, the hepta- and octafluorides:
:TeF
6 + Me
4NF → Me
4NTeF
7
:Me
4NTeF
7 + Me
4NF → (Me
4N)
2TeF
8
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
Frank Albert Cotton FRS (April 9, 1930 – February 20, 2007) was an American chemist. He was the W.T. Doherty-Welch Foundation Chair and Distinguished Professor of Chemistry at Texas A&M University. He authored over 1600 scientific articles. C ...
, 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
External links
Web ElementsOSHA
{{fluorine compounds
Tellurium halides
Hexafluorides
Octahedral compounds
Foul-smelling chemicals
Tellurium(VI) compounds