Uranium pentabromide

Uranium pentabromide
Identifiers
Properties
UBr5
Molar mass 637.549 g/mol
Appearance dark brown, hygroscopic crystalline solid
decomposes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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

  1. ^ 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.
  2. ^ 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.
  3. ^ 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.
  4. ^ 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.