Tellurium tetrafluoride

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Tellurium tetrafluoride
IUPAC name	tellurium(IV) fluoride
Identifiers
CAS number	[15192-26-4]
Properties
Molecular formula	TeF₄
Molar mass	203.594
Appearance	white crystalline solid
Melting point	130 °C
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

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^[1]. The widely reported Te₂F₁₀ has been shown to be F₅TeOTeF₅ ^[1] 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.^[1]

1 Preparation
2 Reactivity
3 Properties
4 References

[edit] 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.

[edit] 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.

[edit] 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.

[edit] 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.