Nickel(II) fluoride
- Nickeldifluorid
Yellow, crystalline solid ( pure substance )
Fixed
4.7 g · cm -3
1450 ° C
Soluble in water
Risk
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Nickel ( II ) fluoride is a chemical compound of the elements nickel and fluorine. The substance is a yellow, very hygroscopic crystalline solid which melts at 1000 ° C. As further forms exist, the nickel (II ) fluoride trihydrate, NiF2 · 3 H 2 O, and nickel (II ) fluoride tetrahydrate, NiF2 · 4 H2O.
Production and representation
Nickel ( II ) fluoride can be synthesized from the elements at elevated temperatures:
Also possible is the reaction of nickel with hydrofluoric acid:
A further possibility is the reaction of nickel ( II) chloride at 350 ° C with fluorine, wherein the chloride ions are oxidized to chlorine:
Properties
Physical Properties
Nickel (II ) fluoride crystallizes in the tetragonal crystal system with space group P42/mnm and the lattice parameters a = 465.08 pm and c = 308.37 pm, in the unit cell contains two formula units.
Nickel (II ) fluoride tetrahydrate crystallizes in the orthorhombic crystal system with space group P21ab and the lattice parameters a = 798.5 pm, b = 1248.2 pm and c = 572 pm, in the unit cell contains four formula units.
Chemical Properties
In case of contact with mineral acids releasing highly toxic hydrogen fluoride, nitric acid as an example here:
The dehydration and chemical nickel ( II ) fluoride tetrahydrate takes place in several stages. At 125 ° C, three molecules of water are released, there arises the monohydrate NiF2 · H2O. At 225 ° C of water and hydrogen fluoride is removed and there is an intermediate product having the stoichiometric composition NiOHF · 3NiF2. Once at 430 ° C and a further molecule of hydrogen fluoride is removed in a water-free atmosphere, a mixture of nickel ( II) oxide and nickel (II ) fluoride remains, otherwise, the final product is pure nickel (II ) oxide.
Complex
Nickel ( II ) fluoride forms complexes with fluoride tetrafluoroethylene:
This tetrafluoroethylene complexes have a layer structure in which NiF6 octahedra are linked together.