Potassium hexafluoronickelate(IV)

Potassium hexafluoronickelate(IV) is an inorganic compound with the chemical formula K
₂NiF
₆. It can be produced through the reaction of potassium fluoride, nickel dichloride, and fluorine.

Potassium hexafluoronickelate(IV)

Names
IUPAC name potassium hexafluoronickelate(IV)
Identifiers
CAS Number	17218-47-2 Y[scifinder]
3D model (JSmol)	Interactive image
ChemSpider	21241633
ECHA InfoCard	100.153.655
EC Number	625-130-0
CompTox Dashboard (EPA)	DTXSID20849392
InChI InChI=1S/6FH.2K.Ni/h6*1H;;;/q;;;;;;2*+1;+4/p-6
SMILES [K+].[K+].F[Ni-2](F)(F)(F)(F)F
Properties
Chemical formula	K2NiF6
Molar mass	250.880
Hazards[1]
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H312, H317, H331, H350
Precautionary statements	P201, P261, P280, P304+P340, P405, P501
Safety data sheet (SDS)	External SDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

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:^{[2][better source needed][3]}

${\displaystyle {\rm {\ 3K_{2}NiF_{6}\xrightarrow {\Delta } 2K_{3}NiF_{6}+NiF_{2}+2F_{2}}}}$

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 ClF⁺
₆ and BrF⁺
₆, respectively:^[4]

${\displaystyle {\rm {\ K_{2}NiF_{6}+5AsF_{5}+XF_{5}{\xrightarrow {aHF}}XF_{6}AsF_{6}+Ni(AsF_{6})_{2}+2KAsF_{6}}}}$

( 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.^[5]

It adopts the structure seen for K₂PtCl₆ and Mg₂FeH₆.^[6]