Uranium pentabromide is an inorganic

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the formula .

Synthesis

The compound is made by reacting the elements in an acetonitrile solvent, or by reacting

bromine Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table (halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simila ...

with

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

metal or uranium tetrabromide at .

Properties

Uranium pentabromide is a

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...

dark brown solid that decomposes in water and most organic solvents, the exceptions being

acetonitrile Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formula and structure . This colourless liquid is the simplest organic nitrile (hydrogen cyanide is a simpler nitrile, but the cyanide anion is not clas ...

dichloromethane Dichloromethane (DCM or methylene chloride, methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible with ...

. The compound is rather unstable and difficult to purify, decomposing at into its constituent elements. The crystal structure is the same as that of β- , which is triclinic and consists of dimers.

Complexes

Stable complexes of the form are known with such

ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...

s as triphenylphosphine oxide and hexamethylphosphoramide, and are obtained by brominating in the presence of the desired ligand. In addition, it is possible to obtain a hexabromouranate(V) salt by reacting with a monovalent bromide in

thionyl bromide Thionyl bromide is the chemical compound SOBr2. It is less stable and less widely used than its chloride analogue, thionyl chloride. It is prepared by the action of hydrogen bromide on thionyl chloride, a characteristic reaction where a stronger ac ...

: :

References

{{Actinide halides Uranium(V) compounds Bromides Actinide halides