Formula UF5 Boiling point 530 °C | Molar mass 333.02 g/mol | |
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Uranium pentafluoride is the inorganic compound with the chemical formula UF5. It is a pale yellow paramagnetic solid. The compound has attracted interest because it is related to uranium hexafluoride, which is widely used to produce uranium fuel. It crystallizes in two polymorphs, called α- and β-UF5.
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Synthesis and structure
It can be produced by reduction of the hexafluoride with carbon monoxide at elevated temperatures.
2 UF6 + CO → 2 UF5 + COF2Other reducing agents have been examined.
The α form is a linear coordination polymer consisting of chains of octahedral uranium centers in which one of the five fluoride anion forms a bridge to the next uranium atom. The structure is reminiscent of that for vanadium pentafluoride.
In β form, the uranium centers adopt a square antiprismatic structure. The β polymorph gradually converts to α at 130 °C.
Monomeric UF5
Of theoretical interest, molecular UF5 can be generated as a transient monomer by UV-photolysis of uranium hexafluoride. It is thought to adopt a square pyramidal geometry.