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.