Related compounds Molar mass 115.9284 g/mol Density 3.88 g/cm³ | Formula CoF3 Melting point 927 °C Appearance brown powder | |
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Cobalt(III) fluoride is the inorganic compound with the formula CoF3. This highly reactive, hygroscopic brown solid is used to synthesize organofluorine compounds. CoF3 is a powerful fluorinating agent that leaves CoF2 as the byproduct.
Contents
Preparation
CoF3 is prepared in the laboratory by treating CoCl2 with fluorine at 250 °C:
CoCl2 + 3/2 F2 → CoF3 + Cl2This 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 + O2CoF3 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 + HFSuch reactions are sometimes accompanied by rearrangements or other reactions. The related reagent KCoF4 is more selective.