Tellurium tetrafluoride

Tellurium tetrafluoride, TeF₄, is a stable, white, hygroscopic crystalline solid and is one of three fluorides of tellurium. The other two binary fluorides are tellurium hexafluoride and ditellurium decafluoride^{[citation needed]}. There are other tellurium compounds that contain fluorine, but only the three mentioned contain solely tellurium and fluorine. Tellurium difluoride is not known.

Additional recommended knowledge

How to ensure accurate weighing results every day?

Correct Test Weight Handling Guide: 12 Practical Tips

How to quickly check pipettes?

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.