The fluoronickelates are a class of chemical compounds containing an anion with nickel at its core, surrounded by fluoride ions which act as ligands. This makes it a fluoroanion. The nickel atom can be in a range of oxidation states from +2, +3 to +4. The hexafluoronickelate(IV)2− ion NiF62− contains nickel in the maximal +4 state, and is in octahedral coordination by the fluoride atoms. It forms a commercially available salt Potassium hexafluoronickelate(IV) K2NiF6. Solid double salts can also contain tetrafluoronickelate NiF4 eg K2NiF4.

formula name Ni Ox structure Remarks references
(NH4)2NiF4 ammonium tetrafluoronickelate 2 Fuse NiCl2 with NH4F, light green color [1][2]
(NH4)2NiF4·2H2O ammonium tetrafluoronickelate dihydrate 2 Formed from Ni(OH)2 and NH4F in water [3]
K2NiF4 potassium tetrafluoronickelate 2 [1]
Rb2NiF4 rubidium tetrafluoronickelate 2 [1]
Ba2NiF6 barium nickel fluoride 2 yellow square plates cas=18115-49-6 [4]
Pb2NiF6 lead(II)nickel(II) fluoride 2 cas=27037-78-1 [4]
Li3NiF6 3 Pna2 C92v a=9.60 Å b=8.37 Å c=4.09 Å Z=4 density=3.27 / 3.24 formed at 500° 70 bar F2 [5][6]
Na3NiF6 sodium hexafluoronickelate 3 violet cas=22707-99-9 [4]
K3NiF6 potassium hexafluoronickelate 3 violet cas=14881-07-3 [4][7]
KCs2NiF6 dicesium potassium hexafluoronickelate 3 lilac colour cas=53479-35-9 [4]
Li2NiF6 lithium hexafluoronickelate 4 hexagonal a=8.321 Å c=4.598 Å V=275.7 Å3 Z=3 pink sol 0.5 g/100 g HF at 0° [5][7]
(O2)2NiF6 dioxygenyl hexafluoronickelate possibly existing, decompose 10° [8][9]
(NO2)2NiF6 dinitronium hexafluoronickelate 4 ΔH=-471 kJ/mol, ΔH0f=-1120 [10]
Na2NiF6 sodium hexafluoronickelate 4 cubic; or tetragonal purple red [11]
K2NiF6 potassium hexafluoronickelate 4 K2PtCl6 structure red cas=17218-47-2 [11]
CaNiF6 calcium hexafluoronickelate 4 ΔH=-363 kJ/mol, ΔH0f=-1951 kJ/mol sold as a fluorine source [10]
Rb2NiF6 rubidium hexafluoronickelate 4 K2PtCl6 structure red cas=17218-48-3 [11]
Cs2NiF6 Cesium hexafluoronickelate 4 K2PtCl6 structure red cas=17218-49-4 [11]
SrNiF6 strontium hexafluoronickelate 4 red cas=66456-12-0 [11]
BaNiF6 barium hexafluoronickelate 4 K2PtCl6 structure red cas=66456-13-1 [11]
(NF4)2NiF6 bis-tetrafluoroammonium hexafluoronickelate 4 tetragonal K2PtCl6 structure red cas=63105-40-8 [11]
(ClF2O)NiF6 bis [difluorooxychlorine (V)] hexafluoronickelate (IV) 4 deep purple, stable to 60 °C [12][13]


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  2. ^ Handbook of inorganic substances 2017
  3. ^ Mellor, J. W. (May 1936). "Nickel". A COMPREHENSIVE TREATISE ON INORGANIC AND THEORETICAL CHEMISTRY VOLUME XV Ni Ru, Rh Pd, Os, Ir. p. 404. Retrieved 31 May 2016.
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  7. ^ a b Chacon, Lisa Carine (December 1997). "The Synthesis, Characterization and Reactivity of High Oxidation State Nickel Fluorides" (PDF). Berkeley California: University of California. Retrieved 27 April 2016.
  8. ^ Bougon, Roland A.; Christe, Karl O.; Wilson, William W. (November 1985). "Dioxygenyl salts containing doubly charged mononuclear counterions". Journal of Fluorine Chemistry. 30 (2): 237–239. doi:10.1016/S0022-1139(00)80892-1.
  9. ^ Marx, Rupert; Seppelt, Konrad (2015). "Structure investigations on oxygen fluorides". Dalton Trans. 44 (45): 19659–19662. doi:10.1039/C5DT02247A. PMID 26351980.
  10. ^ a b Vorobyov, A.F.; Solovyov, S.N.; Minasian, K.A.; Dupal, A.Ja.; Sokolov, V.B.; Spirin, S.N. (September 1991). "Thermochemistry of certain hexafluorometalates and tetrafluoroborates". Journal of Fluorine Chemistry. 54 (1–3): 333. doi:10.1016/S0022-1139(00)83842-7.
  11. ^ a b c d e f g Macintyre, Jane E. (1992-07-23). Dictionary of Inorganic Compounds. CRC Press. p. 3223. ISBN 9780412301209. Retrieved 25 April 2016.
  12. ^ Foulds, G.A. (February 1990). "1. Nickel". Coordination Chemistry Reviews. 98: 2. doi:10.1016/0010-8545(90)80069-6.
  13. ^ Wilson, William W.; Christe, Karl O. (September 1984). "Synthesis and characterization of bis[difluorooxychlorine(V)] hexafluoronickelate(IV), (ClF2O)2NiF6". Inorganic Chemistry. 23 (20): 3261–3262. doi:10.1021/ic00188a048.