Chromium trifluoride

Chromium trifluoride

Names
IUPAC name Chromium(III) fluoride
Other names Chromium trifluoride
Identifiers
CAS Number	7788-97-8 Y 16671-27-5 (trihydrate) 123333-98-2 (tetrahydrate)
ChemSpider	8329529 Y
Jmol 3D model	Interactive image
PubChem	10154021
RTECS number	GB6125000
InChI InChI=1S/Cr.3FH/h;3*1H/q+3;;;/p-3 Y Key: FTBATIJJKIIOTP-UHFFFAOYSA-K Y InChI=1/Cr.3FH/h;3*1H/q+3;;;/p-3 Key: FTBATIJJKIIOTP-DFZHHIFOAR
SMILES [Cr+3].[F-].[F-].[F-]
Properties
Chemical formula	CrF3
Molar mass	108.9913 g/mol (anhydrous) 163.037 g/mol (trihydrate) 181.05 g/mol (tetrahydrate)
Appearance	green crystalline solid
Density	3.8 g/cm3 (anhydrous) 2.2 g/cm3 (trihydrate)
Melting point	1,100 °C (2,010 °F; 1,370 K) (sublimes)
Solubility in water	negligible (anhydrous) sparingly soluble (trihydrate)
Solubility	insoluble in alcohols soluble in HF, HCl
Structure
Crystal structure	Rhombohedral, hR24
Space group	R-3c, No. 167
Vapor pressure	{{{value}}}
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

Chromium(III) fluoride is the name for the inorganic compounds with the chemical formula CrF₃ as well as several related hydrates. The compound CrF₃ is a green crystalline solid that is insoluble in common solvents, but the coloured hydrates [Cr(H₂O)₆]F₃ and [Cr(H₂O)₆]F₃•3H₂O are soluble in water. The trihydrate is green, and the hexahydrate is violet. The anhydrous form sublimes at 1100–1200 °C. Like almost all compounds of chromium(III), these compounds feature octahedral Cr centres. In the anhydrous form, the six coordination sites are occupied by fluoride ligands that bridge to adjacent Cr centres. In the hydrates, some or all of the fluoride ligands are replaced by water.

Production

Chromium(III) fluoride is produced from the reaction of chromium(III) oxide and hydrofluoric acid:

Cr₂O₃ + 6 HF + 9 H₂O → 2 [Cr(H₂O)₆]F₃

The anhydrous form is produced from hydrogen fluoride and chromic chloride:

CrCl₃ + 3 HF → CrF₃ + 3 HCl

Uses

Chromium(III) fluoride is not heavily used, but finds some applications as a mordant in textiles and as a corrosion inhibitor.