Uranium pentabromide

Uranium pentabromide
Identifiers

CAS Number	13775-16-1
PubChem CID	139592
CompTox Dashboard (EPA)	DTXSID40160298
Properties
Chemical formula	UBr₅
Molar mass	637.549 g/mol
Appearance	dark brown, hygroscopic crystalline solid
Solubility in water	decomposes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Chemical compound

Uranium pentabromide is an inorganic chemical compound with the formula U₂Br₁₀.

Synthesis

The compound is made by reacting the elements in an acetonitrile solvent, or by reacting bromine with uranium metal or uranium tetrabromide at 55 °C (131 °F; 328 K).^[1]

Properties

Uranium pentabromide is a hygroscopic dark brown solid that decomposes in water and most organic solvents, the exceptions being acetonitrile or dichloromethane.^[1] The compound is rather unstable and difficult to purify,^[2] decomposing at 80 °C (176 °F; 353 K) into its constituent elements.^[3] The crystal structure is the same as that of β-UCl₅, which is triclinic and consists of U₂Br₁₀ dimers.^[4]

Complexes

Stable complexes of the form UBr₅L are known with such ligands as triphenylphosphine oxide and hexamethylphosphoramide, and are obtained by brominating UBr₄ in the presence of the desired ligand.^[2] In addition, it is possible to obtain a hexabromouranate(V) salt by reacting UBr₅ with a monovalent bromide in thionyl bromide:^[1]

U₂Br₁₀ + 2MBr → 2M⁺[UBr₆]⁻

References

^ ^a ^b ^c Morss, L. R.; Edelstein, Norman M.; Fuger, Jean (2010-10-21). The Chemistry of the Actinide and Transactinide Elements (Set Vol.1-6): Volumes 1-6. Springer Science & Business Media. p. 526. ISBN 978-94-007-0211-0. Retrieved 29 May 2021.
^ ^a ^b Brown, D.; Holah, D. G.; Rickard, C. E. F. (1968-01-01). "The stabilisation of plutonium tetrabromide and uranium pentabromide". Chemical Communications (11): 651–652. doi:10.1039/C19680000651. ISSN 0009-241X.
^ Blair, A.; Ihle, H. (1973-11-01). "The thermal decomposition and thermodynamic properties of uranium pentabromide". Journal of Inorganic and Nuclear Chemistry. 35 (11): 3795–3803. doi:10.1016/0022-1902(73)80071-5. ISSN 0022-1902. Retrieved 29 May 2021.
^ Levy, J.H.; Taylor, J.C.; Wilson, P.W. (1978-01-01). "The crystal structure of uranium pentabromide by powder neutron diffraction". Journal of Inorganic and Nuclear Chemistry. 40 (6): 1055–1057. doi:10.1016/0022-1902(78)80507-7. ISSN 0022-1902. Retrieved 29 May 2021.