Tantalum(V) fluoride

Tantalum(V) fluoride is the chemical compound with the formula. TaF5. Characteristic of other penta and hexafluorides, TaF5 is volatile.

Preparation
It is prepared by treating Ta metal with fluorine gas. NbF5 is prepared similarly.

Structure
Solid and molten TaF5 is tetrameric, consisting of four TaF4 centers linked together via bridging fluoride atoms. Gaseous TaF5 adopts the trigonal pyramidal structure, with D3h symmetry.

Reactions and derivatives
The tendency of TaF5 to form clusters in the solid state indicates the Lewis acidity of the monomer. Indeed, TaF5 reacts with fluoride sources to give the ions [TaF6]-, [TaF7]2-, and [TaF8]3-. With neutral Lewis bases, such as diethyl ether TaF5 forms adducts.