Uranium 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 chemist ...

with the chemical formula UF₅. It is a pale yellow paramagnetic solid. The compound has attracted interest because it is related to

uranium hexafluoride Uranium hexafluoride (), (sometimes called "hex") is an inorganic compound with the formula UF6. Uranium hexafluoride is a volatile white solid that reacts with water, releasing corrosive hydrofluoric acid. The compound reacts mildly with alumin ...

, which is widely used to produce uranium fuel. It crystallizes in two polymorphs, called α- and β-UF₅.

Synthesis and structure

Uranium pentafluoride is an intermediate in the conversion of

uranium tetrafluoride Uranium tetrafluoride is the inorganic compound with the formula UF4. It is a green solid with an insignificant vapor pressure and low solubility in water. Uranium in its tetravalent (uranous) state is important in various technological processe ...

to volatile UF₆: :2UF₄ + F₂ → 2UF₅ :2UF₅ + F₂ → 2UF₆ It can be produced by reduction of the hexafluoride with

carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

at elevated temperatures. : 2UF₆ + CO → 2UF₅ + COF₂ Other reducing agents have been examined. The α form is a linear

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, o ...

consisting of chains of octahedral uranium centers in which one of the five fluoride anion forms a

bridge A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...

to the next uranium atom. The structure is reminiscent of that for

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 ...

. In the β form, the uranium centers adopt a

square antiprism In geometry, the square antiprism is the second in an infinite family of antiprisms formed by an even-numbered sequence of triangle sides closed by two polygon caps. It is also known as an ''anticube''. If all its faces are regular, it is a sem ...

atic

structure A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

. The β polymorph gradually converts to α at 130 °C.

Monomeric UF₅

Of theoretical interest, molecular UF₅ can be generated as a transient

monomer In chemistry, a monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization. Classification Mo ...

by UV-

photolysis Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by photons. It is defined as the interaction of one or more photons with one target molecule. ...

. It is thought to adopt a

square pyramidal In molecular geometry, square pyramidal geometry describes the shape of certain Chemical compound, compounds with the formula where L is a ligand. If the ligand atoms were connected, the resulting shape would be that of a Square pyramid, pyram ...

geometry.

References

{{fluorine compounds Uranium(V) compounds Nuclear materials Fluorides Actinide halides Inorganic polymers Coordination polymers

Synthesis and structure

Monomeric UF5

References

Monomeric UF₅