Fluoronickelate

The fluoronickelates are a class of chemical compounds containing an anion with nickel at its core, surrounded by fluoride ions which act as ligands. 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 octahedral coordination by the fluoride atoms. It forms a commercially available salt Potassium hexafluoronickelate(IV) K₂NiF₆. Solid double salts can contain tetrafluoronickelate NiF₄ eg K₂NiF₄.

formula	name	Ni Ox	structure	Remarks	references
(NH4)2NiF4	ammonium tetrafluoronickelate	2			[1]
K2NiF4	potassium tetrafluoronickelate	2			[1]
Rb2NiF4	rubidium tetrafluoronickelate	2			[1]
Ba2NiF6	barium nickel fluoride	2		yellow square plates cas=18115-49-6	[2]
Pb2NiF6	lead(II)nickel(II) fluoride	2		cas=27037-78-1	[2]
Li3NiF6		3	Pna2 C^92v a=9.60 Å b=8.37 Å c=4.09 Å Z=4 density=3.27 / 3.24	formed at at 500° 70 bar F2	[3][4]
Na3NiF6	sodium hexafluoronickelate	3		violet cas=22707-99-9	[2]
K3NiF6	potassium hexafluoronickelate	3		cas=14881-07-3	[2]
KCs2NiF6	dicesium potassium hexafluoronickelate	3		lilac colour cas=53479-35-9	[2]
Li2NiF6	lithium hexafluoronickelate	4	hexagonal a=8.321 Å c=4.598 Å V=275.7 Å^3 Z=3	pink sol 0.5 g/100 g HF at 0°	[3][5]
(O2)2NiF6	dioxygenyl hexafluoronickelate			possibly existing, decompose 10°	[6][7]
(NO2)2NiF6	dinitronium hexafluoronickelate	4		ΔH=-471 kJ/mol, ΔH^0f=-1120	[8]
Na2NiF6	sodium hexafluoronickelate	4	cubic; or tetragonal	purple red	[9]
K2NiF6	potassium hexafluoronickelate	4	K2PtCl6 structure	red cas=17218-47-2	[9]
CaNiF6	calcium hexafluoronickelate	4		ΔH=-363 kJ/mol, ΔH^0f=-1951 kJ/mol sold as a fluorine source	[8]
Rb2NiF6	rubidium hexafluoronickelate	4	K2PtCl6 structure	red cas=17218-48-3	[9]
Cs2NiF6	Cesium hexafluoronickelate	4	K2PtCl6 structure	red cas=17218-49-4	[9]
SrNiF6	strontium hexafluoronickelate	4		red cas=66456-12-0	[9]
BaNiF6	barium hexafluoronickelate	4	K2PtCl6 structure	red cas=66456-13-1	[9]
(NF4)2NiF6	bis-tetrafluoroammonium hexafluoronickelate	4	tetragonal K2PtCl6 structure	red cas=63105-40-8	[9]

References

1. Chaudhuri, Mihir K.; Ghosh, Soumitra K.; Hiese, Zavei (1984). "Synthesis of tetrafluoronickelate(II) and tetrafluorozincate(II) complexes from aqueous media: a novel route to fluorometalates". Journal of the Chemical Society, Dalton Transactions (8): 1763. doi:10.1039/DT9840001763.
2. Macintyre, Jane E. Dictionary of Inorganic Compounds. CRC Press. p. 3222. ISBN 9780412301209. Retrieved 25 April 2016.
3. Whalen, J.M.; Lucier, G.M.; Chacón, L.; Bartlett, N. (March 1998). "The room temperature conversion of nickel difluoride to hexafluoronickelate(IV) salts of alkali cations". Journal of Fluorine Chemistry 88 (2): 107–110. doi:10.1016/S0022-1139(98)00105-5.
4. Grannec, J.; Lozano, L.; Sobre, P.; Portier, J.; Hagenmuller, P. (September 1975). "Sur un nouvel hexafluorure de nickel trivalent de formule Li3NiF6.". Journal of Fluorine Chemistry (in French) 6 (3): 267–274. doi:10.1016/S0022-1139(00)83005-5.
5. 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.
6. 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. Retrieved 29 April 2016.
7. Marx, Rupert; Seppelt, Konrad (2015). "Structure investigations on oxygen fluorides". Dalton Trans. 44 (45): 19659–19662. doi:10.1039/C5DT02247A.
8. 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.
9. Macintyre, Jane E. Dictionary of Inorganic Compounds. CRC Press. p. 3223. ISBN 9780412301209. Retrieved 25 April 2016.