Cobalt(III) fluoride: Difference between revisions
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Such reactions are sometimes accompanied by rearrangements or other reactions.<ref name=Coe/> The related reagent KCoF<sub>4</sub> is more selective.<ref>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}}.</ref> |
Such reactions are sometimes accompanied by rearrangements or other reactions.<ref name=Coe/> The related reagent KCoF<sub>4</sub> is more selective.<ref>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}}.</ref> |
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==Molecular and Electronic Structures== |
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Co<sub>3</sub> is calculated to be planar in its ground state, and has a 3-fold rotation axis (symmetry notation D<sub>3h</sub>). The Cr<sup>3+</sup> ion has a ground state of 3d<sup>6</sup> <sup>5</sup>D. The fluoride ligands split this state into, in energy order, <sup>5</sup>A', <sup>5</sup>E", and <sup>5</sup>E' states. The first energy difference is small and the <sup>5</sup>E" state is subject to the [[Jahn-Teller Effect]], so this effect needs to be considered to be sure of the ground state. The energy lowering is small and does not change the energy order.<ref>{{cite=journal | last1=Yates | first1=JH | last2=Pitzer | first2=RM | date=1979 | title = Molecular and Electronic Structure of Transition Metal Trifluorides | journal = J. Chem. Phys. | volume = 70 | issue = 9 | pages = 4049-4055 | doi = 10.1063/1.438027}}</ref> This calculation was the first treatment of the [[Jahn-Teller Effect]] using calculated energy surfaces. |
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==References== |
==References== |
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Revision as of 00:39, 24 September 2018
-fluoride-3D-balls.png)
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| Names | |
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| Other names
Cobalt trifluoride
Cobaltic fluoride Cobalt fluoride Cobaltic trifluoride | |
| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.030.045 |
| EC Number |
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PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| CoF3 | |
| Molar mass | 115.928 g/mol |
| Appearance | brown powder |
| Density | 3.88 g/cm3 |
| Melting point | 927 °C (1,701 °F; 1,200 K) |
| reacts | |
| +1900.0·10−6 cm3/mol | |
| Structure | |
| hexagonal | |
| Hazards | |
| NFPA 704 (fire diamond) | |
| Related compounds | |
Other anions
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cobalt(III) oxide, cobalt(III) chloride |
Other cations
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iron(III) fluoride, rhodium(III) fluoride |
Related compounds
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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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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]
Molecular and Electronic Structures
Co3 is calculated to be planar in its ground state, and has a 3-fold rotation axis (symmetry notation D3h). The Cr3+ ion has a ground state of 3d6 5D. The fluoride ligands split this state into, in energy order, 5A', 5E", and 5E' states. The first energy difference is small and the 5E" state is subject to the Jahn-Teller Effect, so this effect needs to be considered to be sure of the ground state. The energy lowering is small and does not change the energy order.[4] This calculation was the first treatment of the Jahn-Teller Effect using calculated energy surfaces.
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:10.1002/047084289X.rc185.
- ^ Priest, H. F. "Anhydrous Metal Fluorides" Inorganic Syntheses McGraw-Hill: New York, 1950; Vol. 3, pages 171-183. doi:10.1002/9780470132340.ch47
- ^ 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.
- ^ Template:Cite=journal
External links
