Cobalt(III) fluoride

Cobalt(III) fluoride
Names
Other names
Cobalt trifluoride
Cobaltic fluoride
Cobalt fluoride
Cobaltic trifluoride
Identifiers
10026-18-3 YesY
3D model (Jmol) Interactive image
ChemSpider 59593 YesY
ECHA InfoCard 100.030.045
EC Number 233-062-4
PubChem 66208
UNII O3R680UKNX YesY
Properties
CoF3
Molar mass 115.928 g/mol
Appearance brown powder
Density 3.88 g/cm3
Melting point 92 °C (198 °F; 365 K)
reacts
Structure
hexagonal
Hazards
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
0
3
2
Related compounds
Other anions
 cobalt(III) oxide, cobalt(III) chloride
Other cations
 iron(III) fluoride, rhodium(III) fluoride
Related compounds
 cobalt(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

Cobalt(III) fluoride is the inorganic compound with the formula CoF3. This highly reactive, hygroscopic brown solid is used to synthesize organofluorine compounds.[1] CoF3 is a powerful fluorinating agent that leaves CoF2 as the byproduct.

Preparation

CoF3 is prepared in the laboratory by treating CoCl2 with fluorine at 250 °C:[2]

CoCl2 + 3/2 F2 → CoF3 + Cl2

This conversion is a redox reaction: Co2+ and Cl− are oxidized to Co3+ and Cl2, respectively, while F2 is reduced to F−. Cobalt(II) oxide (CoO) and cobalt(II) fluoride (CoF2) can also be converted to cobalt(III) fluoride using fluorine.

Reactions

CoF3 decomposes upon contact with water to give oxygen:

4 CoF3 + 2 H2O → 4 HF + 4 CoF2 + O2

CoF3 is hygroscopic, forming a dihydrate (CAS#54496-71-8). It reacts with fluoride sources to give the anion [CoF6]3−, which is a rare example of a high-spin, octahedral cobalt(III) complex.

Applications

Used as slurry, CoF3 converts hydrocarbons to the perfluorocarbons:

2CoF3 + R-H → 2CoF2 + R-F + HF

Such reactions are sometimes accompanied by rearrangements or other reactions.[1] The related reagent KCoF4 is more selective.[3]

References

  1. 1 2 Coe, P. L. "Cobalt(III) Fluoride" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289X.rc185.
  2. ↑ Priest, H. F. "Anhydrous Metal Fluorides" Inorganic Syntheses McGraw-Hill: New York, 1950; Vol. 3, pages 171-183. doi:10.1002/9780470132340.ch47
  3. ↑ Coe, P. L. "Potassium Tetrafluorocobaltate(III)" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289X.rp251.
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