Chromium pentafluoride is the inorganic compound with the chemical formula CrF5.[1] It is a red volatile solid that melts at 34 °C. It is the highest known chromium fluoride, since the hypothetical chromium hexafluoride has not yet been synthesized.[2]
Chromium pentafluoride is one of the products of the action of fluorine on a mixture of potassium and chromic chlorides.[3]
In terms of its structure, the compound is a one-dimensional coordination polymer. Each Cr(V) center has octahedral molecular geometry.[4] It has the same crystal structure as vanadium pentafluoride.[5]
Chromium pentafluoride is strongly oxidizing, able to fluorinate the noble gas xenon and oxidize dioxygen to dioxygenyl.[4] Due to this property, it decomposes readily in the presence of reducing agents, and easily hydrolyses to chromium(III) and chromium(VI).[6]
Chromium pentafluoride can react with Lewis bases such as caesium fluoride and nitryl fluoride to give the respective hexafluorochromate(V) salt.[7]
CrF5 + CsF → CsCrF6
Chromium pentafluoride can also react with the Lewis acid antimony pentafluoride to give the CrF5·2SbF5 adduct. The adduct was found to be a strong oxidizing agent, liquid at room temperature with a melting point of −23 °C.