3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||115.928 g/mol|
|Melting point||927 °C (1,701 °F; 1,200 K)|
|cobalt(III) oxide, cobalt(III) chloride|
|iron(III) fluoride, rhodium(III) fluoride|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Cobalt(III) fluoride is the inorganic compound with the formula CoF
3. Hydrates are also known. The anhydrous compound is a hygroscopic brown solid. It is used to synthesize organofluorine compounds.
Anhydrous cobalt trifluoride crystallizes in the rhombohedral group, specifically according to the aluminium trifluoride motif, with a = 527.9 pm, α = 56.97°. Each cobalt atom is bound to six fluorine atoms in octahedral geometry, with Co–F distances of 189 pm. Each fluoride is a doubly bridging ligand. 
A hydrate CoF
3 · 3.5H2O is known. It is conjectured to be better described as [CoF
3] · 0.5H2O.
There is a report of an hydrate CoF
3 · 3.5H2O, isomorphic to AlF
3 · 3H2O.
In this redox reaction, Co2+ and Cl− are oxidized to Co3+ and Cl
2, respectively, while F
2 is reduced to F−. Cobalt(II) oxide (CoO) and cobalt(II) fluoride (CoF
2) can also be converted to cobalt(III) fluoride using fluorine.
3 decomposes upon contact with water to give oxygen:
It reacts with fluoride salts to give the anion [CoF6]3−, which is also features high-spin, octahedral cobalt(III) center.
2 is the byproduct.
In the gas phase, CoF
3 is calculated to be planar in its ground state, and has a 3-fold rotation axis (symmetry notation D3h). The Co3+ 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. This calculation was the first treatment of the Jahn-Teller Effect using calculated energy surfaces.
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