Tellurium tetrafluoride

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IUPACName = tellurium(IV) fluoride
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CASNo = 15192-26-4
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Section2 = Chembox Properties
Formula = TeF₄
MolarMass = 203.594
Appearance = white crystalline solid
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MeltingPt = 130 °C
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Tellurium tetrafluoride, TeF₄, is a stable, white, hygroscopic crystalline solid and is one of two fluorides of tellurium. The other binary fluoride is tellurium hexafluoride"Inorganic Chemistry",Egon Wiberg, Arnold Frederick Holleman Elsevier 2001 ISBN 0123526515] . The widely reported Te₂F₁₀ has been shown to be F₅TeOTeF₅ There are other tellurium compounds that contain fluorine, but only the two mentioned contain solely tellurium and fluorine. Tellurium difluoride, TeF₂, and ditellurium fluoride, Te₂F are not known.

Preparation

Tellurium tetrafluoride can be prepared by the following reaction:
TeO₂ + 2SF₄ → TeF₄ + 2SOF₂
It is also prepared by reacting nitryl fluoride with tellurium or from the elements at 0 °C or by reacting selenium tetrafluoride with tellurium dioxide at 80 °C.
Fluorine in nitrogen can react with TeCl₂ or TeBr₂ to form TeF₄. PbF₂ will also fluorinate tellurium to TeF₄.

Reactivity

Tellurium tetrafluoride will react with water or silica and forms tellurium oxides. Copper, silver, gold or nickel will react with tellurium tetrafluoride at 185 °C. It does not react with platinum. It is soluble in SbF₅ and will precipitate out the complex TeF₄SbF₅.

Properties

Tellurium tetrafluoride melts at 130 °C and decomposes to tellurium hexafluoride at 194 °C. In the solid phase it consists of infinite chains of TeF₃F_2/2 in an octahedral geometry. A lone pair of electrons occupies the sixth position.

References

*R.B. King; "Inorganic Chemistry of Main Group Elements", VCH Publishers, New York, 1995.
*W.C. Cooper; "Tellurium", VanNostrand Reinhold Company, New York, 1971.