Potassium hexafluoronickelate(IV)

Potassium hexafluoronickelate(IV) is an inorganic compound with the chemical formula. It can be produced through the reaction of potassium fluoride, nickel dichloride, and fluorine.

It reacts violently with water, releasing oxygen. It dissolves in anhydrous hydrogen fluoride to produce a light-red solution. Potassium hexafluoronickelate(IV) decomposes at 350 °C, forming potassium hexafluoronickelate(III), nickel(II) fluoride, and fluorine:


 * $$\rm \ 3 K_2NiF_6 \xrightarrow{\Delta} 2 K_3NiF_6 + NiF_2 + F_2$$



Potassium hexafluoronickelate is a strong oxidant. It can turn chlorine pentafluoride and bromine pentafluoride into and, respectively:


 * $$\rm \ K_2NiF_6 + 5 AsF_5 + XF_5 \xrightarrow{aHF} XF_6AsF_6 + Ni(AsF_6)_2 + 2KAsF_6$$
 * ( X = Cl or Br, -60 °C , aHF = anhydrous hydrogen fluoride).

Potassium hexafluoronickelate decomposes at high temperatures to release fluorine gas; like terbium(IV) fluoride, the emitted fluorine is primarily monatomic rather than the typical diatomic.

It adopts the structure seen for K2PtCl6 and Mg2FeH6.