Chromium pentafluoride is the

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemis ...

with the chemical formula CrF₅. 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. Chromium pentafluoride is one of the products of the action of fluorine on a mixture of potassium and chromic chlorides. In terms of its structure, the compound is a one-dimensional

coordination polymer A coordination polymer is an inorganic or organometallic polymer structure containing metal cation centers linked by ligands. More formally a coordination polymer is a coordination compound with repeating coordination entities extending in 1, 2 ...

. Each Cr(V) center has

octahedral molecular geometry In chemistry, octahedral molecular geometry, also called square bipyramidal, describes the shape of compounds with six atoms or groups of atoms or ligands symmetrically arranged around a central atom, defining the vertices of an octahedron. The o ...

. It has the same

crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric pattern ...

vanadium pentafluoride Vanadium(V) fluoride is the inorganic compound with the chemical formula VF5. It is a colorless volatile liquid. It is a highly reactive compound, as indicated by its ability to fluorinate organic substances. Properties and structure The comp ...

. Chromium pentafluoride is strongly oxidizing, able to fluorinate the noble gas

xenon Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

and oxidize

dioxygen There are several known allotropes of oxygen. The most familiar is molecular oxygen (O2), present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen. Another is the highly reactive ozone (O3). Others are: * ...

dioxygenyl The dioxygenyl ion, , is a rarely-encountered oxycation in which both oxygen atoms have a formal oxidation state of . It is formally derived from oxygen by the removal of an electron: :O2 → + e− The energy change for this process is call ...

. Due to this property, it decomposes readily in the presence of reducing agents, and easily

hydrolyses Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...

chromium(III) Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal. Chromium metal is valued for its high corrosion resistance and hardne ...

and chromium(VI).

Reactions

Chromium pentafluoride can react with

Lewis bases A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any spe ...

such as

caesium fluoride Caesium fluoride or cesium fluoride is an inorganic compound with the formula CsF and it is a hygroscopic white salt. Caesium fluoride can be used in organic synthesis as a source of the fluoride anion. Caesium also has the highest electropositivi ...

and

nitryl fluoride Nitryl fluoride, NO2F, is a colourless gas and strong oxidizing agent, which is used as a fluorinating agent and has been proposed as an oxidiser in rocket propellants (though never flown). It is a molecular species, not ionic, consistent with it ...

to give the respective hexafluorochromate(V) salt. :CrF₅ + CsF → CsCrF₆ Chromium pentafluoride can also react with the Lewis acid

antimony pentafluoride Antimony pentafluoride is the inorganic compound with the formula Sb F5. This colourless, viscous liquid is a valuable Lewis acid and a component of the superacid fluoroantimonic acid, formed when mixing liquid HF with liquid SbF5 in a 2:1 ratio ...

to give the CrF₅·2SbF₅

adduct An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all co ...

. The adduct was found to be a strong oxidizing agent, liquid at room temperature with a melting point of −23 °C.

References

Chromium–halogen compounds Fluorides Metal halides Chromium(V) compounds {{inorganic-compound-stub

Reactions

See also

References