Tellurium tetrafluoride, TeF<sub>4</sub>, is a stable, white, hygroscopic crystalline solid and is one of two fluorides of tellurium. The other binary fluoride is tellurium hexafluoride. The widely reported Te<sub>2</sub>F<sub>10</sub> has been shown to be F<sub>5</sub>TeOTeF<sub>5</sub> (teflic anhydride). There are other tellurium compounds that contain fluorine, but only the two mentioned contain solely tellurium and fluorine. Tellurium difluoride, TeF<sub>2</sub>, and ditellurium difluoride, Te<sub>2</sub>F<sub>2</sub> are not known.
Tellurium tetrafluoride can be prepared reacting tellurium dioxide with sulfur tetrafluoride:
It is also prepared by reacting nitryl fluoride with tellurium or from the elements at 0 ðC or by reacting selenium tetrafluoride with tellurium dioxide at 80 ðC.<br> Fluorine in nitrogen can react with TeCl<sub>2</sub> or TeBr<sub>2</sub> to form TeF<sub>4</sub>. PbF<sub>2</sub> will also fluorinate tellurium to TeF<sub>4</sub>.
Tellurium tetrafluoride will react with water or silica and forms tellurium oxides. Copper, silver, gold or nickel will react with tellurium tetrafluoride at 185 ðC. It does not react with platinum. It is soluble in SbF<sub>5</sub> and will precipitate out the complex TeF<sub>4</sub>SbF<sub>5</sub>.
Tellurium tetrafluoride melts at 130 ðC and decomposes to tellurium hexafluoride at 194 ðC. In the solid phase, it consists of infinite chains of TeF<sub>3</sub>F<sub>2/2</sub> in an octahedral geometry. A lone pair of electrons occupies the sixth position.