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 ðC, forming potassium hexafluoronickelate(III), nickel(II) fluoride, and fluorine:
Potassium hexafluoronickelate is a strong oxidant. It can turn chlorine pentafluoride and bromine pentafluoride into and , respectively:
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 K<sub>2</sub>PtCl<sub>6</sub> and Mg<sub>2</sub>FeH<sub>6</sub>.