Potassium hexafluoronickelate(IV)

Template:Chembox Potassium hexafluoronickelate(IV) is an inorganic compound with the chemical formula Template:Chem. 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:Template:Better source needed

$\mathrm{3}{\mathrm{K}}_{\mathrm{2}}\mathrm{N}\mathrm{i}{\mathrm{F}}_{\mathrm{6}}\stackrel{\mathrm{\Delta }}{\to }\mathrm{2}{\mathrm{K}}_{\mathrm{3}}\mathrm{N}\mathrm{i}{\mathrm{F}}_{\mathrm{6}}\mathrm{+}\mathrm{N}\mathrm{i}{\mathrm{F}}_{\mathrm{2}}\mathrm{+}\mathrm{2}{\mathrm{F}}_{\mathrm{2}}$

Chemical structure of solid K₂NiF₆ as determined by X-ray crystallography.

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

${\mathrm{K}}_{\mathrm{2}}\mathrm{N}\mathrm{i}{\mathrm{F}}_{\mathrm{6}}\mathrm{+}\mathrm{5}\mathrm{A}\mathrm{s}{\mathrm{F}}_{\mathrm{5}}\mathrm{+}\mathrm{X}{\mathrm{F}}_{\mathrm{5}}\stackrel{aHF}{\to }\mathrm{X}{\mathrm{F}}_{\mathrm{6}}\mathrm{A}\mathrm{s}{\mathrm{F}}_{\mathrm{6}}\mathrm{+}\mathrm{N}\mathrm{i}\mathrm{(}\mathrm{A}\mathrm{s}{\mathrm{F}}_{\mathrm{6}}{\mathrm{)}}_{\mathrm{2}}\mathrm{+}\mathrm{2}\mathrm{K}\mathrm{A}\mathrm{s}{\mathrm{F}}_{\mathrm{6}}$

( 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.

References

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