Uranium pentabromide

The compound is made by reacting the elements in an acetonitrile solvent, or by reacting bromine with uranium metal or uranium tetrabromide at {{convert|55|C|F K}}.

Uranium pentabromide is a hygroscopic dark brown solid that decomposes in water and most organic solvents, the exceptions being acetonitrile or dichloromethane.{{cite book |last1=Morss |first1=L. R. |last2=Edelstein |first2=Norman M. |last3=Fuger |first3=Jean |title=The Chemistry of the Actinide and Transactinide Elements (Set Vol.1-6): Volumes 1-6 |date=2010-10-21 |publisher=Springer Science & Business Media |isbn=978-94-007-0211-0 |page=526 |url=https://books.google.com/books?id=9vPuV3A0UGUC&pg=PA526 |access-date=29 May 2021 |language=en}} The compound is rather unstable and difficult to purify,{{cite journal |last1=Brown |first1=D. |last2=Holah |first2=D. G. |last3=Rickard |first3=C. E. F. |title=The stabilisation of plutonium tetrabromide and uranium pentabromide |journal=Chemical Communications |date=1968-01-01 |issue=11 |pages=651–652 |doi=10.1039/C19680000651 |url=https://pubs.rsc.org/en/content/articlelanding/1968/c1/c19680000651 |language=en |issn=0009-241X|url-access=subscription }} decomposing at {{convert|80|C|F K}} into its constituent elements.{{cite journal |title=The thermal decomposition and thermodynamic properties of uranium pentabromide |journal=Journal of Inorganic and Nuclear Chemistry |date=1973-11-01 |volume=35 |issue=11 |pages=3795–3803 |doi=10.1016/0022-1902(73)80071-5 |url=https://www.sciencedirect.com/science/article/abs/pii/0022190273800715 |access-date=29 May 2021 |language=en |issn=0022-1902|last1=Blair |first1=A. |last2=Ihle |first2=H. |url-access=subscription }} The crystal structure is the same as that of β-uranium pentachloride, which is triclinic and consists of {{chem2|U2Br10}} dimers.{{cite journal |title=The crystal structure of uranium pentabromide by powder neutron diffraction |journal=Journal of Inorganic and Nuclear Chemistry |date=1978-01-01 |volume=40 |issue=6 |pages=1055–1057 |doi=10.1016/0022-1902(78)80507-7 |url=https://www.sciencedirect.com/science/article/abs/pii/0022190278805077 |access-date=29 May 2021 |language=en |issn=0022-1902|last1=Levy |first1=J.H. |last2=Taylor |first2=J.C. |last3=Wilson |first3=P.W. |url-access=subscription }}

Stable complexes of the form {{chem2|UBr5L}} are known with such ligands as triphenylphosphine oxide and hexamethylphosphoramide, and are obtained by brominating {{chem2|UBr4}} in the presence of the desired ligand. In addition, it is possible to obtain a hexabromouranate(V) salt by reacting {{chem2|UBr5}} with a monovalent bromide in thionyl bromide:

:{{chem2|U2Br10 + 2MBr -> 2M+[UBr6]-}}

{{reflist}}

{{uranium compounds}}

{{Bromides}}

{{Actinide halides}}

Category:Uranium(V) compounds

Category:Bromides

Category:Actinide halides