Chromium(II) fluoride

Chromium(II) fluoride

200px      Cr2+      F−
Names
Other names chromium difluoride, chromium fluouride, chromous fluoride
Identifiers
CAS Number	10049-10-2
ChemSpider	59614
EC Number	233-168-0
Jmol 3D model	Interactive image
PubChem	66229
InChI InChI=1S/Cr.2FH/h;2*1H/q+2;;/p-2 Key: RNFYGEKNFJULJY-UHFFFAOYSA-L
SMILES [F-].[F-].[Cr+2]
Properties
Chemical formula	CrF2
Molar mass	89.99 g·mol−1
Appearance	blue-green iridescent crystals hygroscopic, turns to Cr2O3 when heated in air
Density	3.79 g/cm3
Melting point	894 °C (1,641 °F; 1,167 K)
Boiling point	> 1,300 °C (2,370 °F; 1,570 K)
Solubility in water	76.7 g/100 mL
Structure
Crystal structure	monoclinic
Thermochemistry
Std enthalpy of formation (ΔfHo298)	-8.645 kJ/g (solid)
Vapor pressure	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Chromium(II) fluoride is an inorganic compound with the formula CrF₂. It exists as a blue-green iridescent solid. Chromium(II) fluoride is sparingly soluble in water, almost insoluble in alcohol, and is soluble in boiling hydrochloric acid, but is not attacked by hot distilled sulfuric acid or nitric acid. Like other chromous compounds, chromium(II) fluoride is oxidized to chromium(III) oxide in air.

Preparation and structure

The compound is prepared by passing anhydrous hydrogen fluoride over anhydrous chromium(II) chloride. The reaction will proceed at room temperature but is typically heated to 100-200 °C to ensure completion:

CrCl₂ + 2 HF → CrF₂ + 2 HCl

Like many difluorides, CrF₂ adopts a structure like rutile with octahedral molecular geometry about Cr(II) and trigonal geometry at F⁻. Two of the six Cr-F bonds are long at 2.43 Å, and four are short near 2.00 Å.

See also

• Chromyl fluoride
• Chromium(II) chloride

External links

• Crystal Structure