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. This makes it a fluoroanion. The nickel atom can be in a range of oxidation states from +2, +3 to +4.
The hexafluoronickelate2− 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 |
| 2NiF4 | ammonium tetrafluoronickelate | 2 | Fuse NiCl2 with NH4F, light green color | ||
| 2NiF4·2H2O | ammonium tetrafluoronickelate dihydrate | 2 | Formed from Ni2 and NH4F in water | ||
| K2NiF4 | potassium tetrafluoronickelate | 2 | |||
| Rb2NiF4 | rubidium tetrafluoronickelate | 2 | |||
| Ba2NiF6 | barium nickel fluoride | 2 | yellow square plates cas=18115-49-6 | ||
| Pb2NiF6 | leadnickel fluoride | 2 | cas=27037-78-1 | ||
| 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 | ||
| Na3NiF6 | sodium hexafluoronickelate | 3 | violet cas=22707-99-9 | ||
| K3NiF6 | potassium hexafluoronickelate | 3 | violet cas=14881-07-3 | ||
| KCs2NiF6 | dicesium potassium hexafluoronickelate | 3 | lilac colour cas=53479-35-9 | ||
| - | - | - | - | - | |
| 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° | |
| 2NiF6 | dioxygenyl hexafluoronickelate | possibly existing, decompose 10° | |||
| 2NiF6 | dinitronium hexafluoronickelate | 4 | ΔH=-471 kJ/mol, ΔH0f=-1120 | ||
| Na2NiF6 | sodium hexafluoronickelate | 4 | cubic; or tetragonal | purple red | |
| K2NiF6 | potassium hexafluoronickelate | 4 | K2PtCl6 structure | red cas=17218-47-2 | |
| CaNiF6 | calcium hexafluoronickelate | 4 | ΔH=-363 kJ/mol, ΔH0f=-1951 kJ/mol sold as a fluorine source | ||
| Rb2NiF6 | rubidium hexafluoronickelate | 4 | K2PtCl6 structure | red cas=17218-48-3 | |
| Cs2NiF6 | Cesium hexafluoronickelate | 4 | K2PtCl6 structure | red cas=17218-49-4 | |
| SrNiF6 | strontium hexafluoronickelate | 4 | red cas=66456-12-0 | ||
| BaNiF6 | barium hexafluoronickelate | 4 | K2PtCl6 structure | red cas=66456-13-1 | |
| 2NiF6 | bis-tetrafluoroammonium hexafluoronickelate | 4 | tetragonal K2PtCl6 structure | red cas=63105-40-8 | |
| NiF6 | bis hexafluoronickelate | 4 | deep purple, stable to 60 °C |