Nickel(II) fluoride

Nickel(II) fluoride is the chemical compound with the formula NiF2. Its is an ionic compound of nickel and fluorine and forms yellowish to green tetragonal crystals. Unlike many fluorides, NiF2 is stable in air.

Nickel(II) fluoride
Names
IUPAC name
Nickel(II) fluoride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.053
EC Number
  • 233-071-3
RTECS number
  • QR6825000
UNII
Properties
NiF2
Molar mass 96.6902 g/mol
Appearance Yellowish to green tetragonal crystals
Density 4.72 g/cm3
Melting point 1,474 °C (2,685 °F; 1,747 K) [1]
Boiling point 1,750 °C (3,180 °F; 2,020 K) [2]
4 g/100 mL
Solubility insoluble in alcohol, ether
+2410.0·10−6 cm3/mol
Structure
Rutile
Nickel: Octahedral
Oxygen: Trigonal planar
Hazards
Safety data sheet External MSDS
Related compounds
Other anions
 Nickel(II) chloride
Nickel(II) bromide
Nickel(II) iodide
Other cations
 Cobalt(II) fluoride
Copper(II) fluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

NiF2 comprises the passivating surface that forms on nickel alloys (e.g. monel) in the presence of hydrogen fluoride or elemental fluorine, which is why nickel and its alloys are among the few materials that can be used to store or transport these fluorine compounds. NiF2 is also used as a catalyst for the synthesis of chlorine pentafluoride.

Preparation

NiF2 is prepared by treatment of anhydrous nickel(II) chloride with fluorine at 350 °C:[3]

NiCl2 + F2 → NiF2 + Cl2

The corresponding reaction of cobalt(II) chloride results in oxidation of the cobalt, whereas nickel remains in the +2 oxidation state after fluorination because its +3 oxidation state is less stable. Chloride is more easily oxidized than nickel(II). This is a typical halogen displacement reaction, where a halogen plus a less active halide makes the less active halogen and the more active halide.

Nickel(II) fluoride is also produced when fluorine reacts with nickel metal.

Reactions

A melt of NiF2 and KF reacts to give the green compound K2[NiF4]. The structure of this material is closely related to some superconducting oxide materials.[4]

Nickel(II) fluoride reacts with strong bases to make nickel(II) hydroxide, a green colored compound.

NiF2 + 2 NaOH → Ni(OH)2 + 2 NaF

References
  1. http://www.slac.stanford.edu/BFROOT/www/Detector/Backgrounds/BkG4Sim/Planning/Validations/neutronCounters/04_02_85.pdf
  2. http://www.indiamart.com/primechemicals/inorganic-fluorine.html
  3. Priest, H. F. “Anhydrous Metal Fluorides” Inorganic Syntheses McGraw-Hill: New York, 1950; Vol. 3, pages 171-183.
  4. Balz, D. "Über die Struktur des K2NiF4" Naturwissenschaften 1953, page 241.
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