Chromium(II) fluoride is an inorganic compound with the formula CrF<sub>2</sub>. 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.
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 ðC to ensure completion:
Like many difluorides, CrF<sub>2</sub> adopts a structure like rutile with octahedral molecular geometry about Cr(II) and trigonal geometry at F<sup>âÂÂ</sup>. Two of the six CrâÂÂF bonds are long at 2.43 à, and four are short near 2.00 à. This distortion is a consequence of the JahnâÂÂTeller effect that arises from the d<sup>4</sup> electron configuration of the chromium(II) ion.