Cobalt(III) fluoride

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Cobalt(III) fluoride

Other names	Cobalt trifluoride Cobaltic fluoride Cobalt fluoride Cobaltic trifluoride
Identifiers
CAS number	[10026-18-3]
Properties
Molecular formula	CoF₃
Molar mass	115.93 g/mol
Density	3.88 g/cm³
Melting point	926 °C
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Cobalt(III) fluoride is the chemical compound with the formula CoF₃. This highly reactive, hygroscopic brown solid is used to synthesize organofluorine compounds.^[1] CoF₃ is a powerful fluorinating agent, the product being CoF₂. It decomposes upon contact with water to give oxygen.

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⁺ is converted to Co³⁺ and chloride to chlorine. Cobalt(II) oxide (CoO) and cobalt(II) fluoride (CoF₂) can also be converted to cobalt(III) fluoride using fluorine.

CoF₃ is hygroscopic and can be converted to the anion [CoF₆]^3-, a rare example of a high-spin, octahedral cobalt(III) complex.

Used as slurry, CoF₃ converts hydrocarbons to the perfluorocarbons:

2CoF₃ + R-H → CoF₂ + R-F + HF

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

[edit] References

^ ^a ^b Coe, P. L. "Cobalt(III) Fluoride" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.
^ Priest, H. F. “Anhydrous Metal Fluorides” Inorganic Syntheses McGraw-Hill: New York, 1950; Vol. 3, pages 171-183.
^ Coe, P. L. "Potassium Tetrafluorocobaltate(III)" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.