Ammonium hexafluorotitanate

Ammonium hexafluorotitanate is the inorganic compound with the chemical formula (NH4)2[TiF6]. A colorless salt, the compound consists of ammonium ions and the hexafluorotitanate dianion. It is encountered in the extraction of titanium from its principal ore ilmenite: the ore is treated with excess ammonium fluoride:
 * FeTiO3 + 10 NH4F  ->  (NH4)2FeF4  +  (NH4)2TiF6  +  6 H2O

After removal of iron impurities, the titanium is recovered as a hydrated titanium dioxide by treatment of the aqueous extract of the hexafluoride with ammonia:
 * (NH4)2TiF6 + 4 NH3  +  2 H2O  ->  TiO2  +  6 NH4F

Structure
Many salts of hexafluorotitanate have been characterized by X-ray crystallography. In the lattice [TiF6]2- octahedra interact with the ammonium cations by hydrogen bonds.