Bismuth tribromide is an inorganic compound of

bismuth Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs ...

and

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 simi ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...

BiBr₃.

Preparation

It may be formed by the reaction of bismuth oxide and hydrobromic acid. : Bismuth tribromide can also be produced by the direct oxidation of bismuth in bromine. :

Structure

Bismuth tribromide adopts two different structures in the solid state: a low-temperature polymorph α-BiBr₃ that is stable below 158 °C and a high-temperature polymorph β-BiBr₃ that is stable above this temperature. Both polymorphs are monoclinic but α-BiBr₃ is in

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it uncha ...

''P''2₁/a whereas β-BiBr₃ is in ''C''2/m. α-BiBr₃ consists of

pyramidal A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilater ...

molecules whereas β-BiBr₃ is polymeric and adopts the AlCl₃ structure. BiBr₃ is the only

group 15 A pnictogen ( or ; from grc, πνῑ́γω "to choke" and -gen, "generator") is any of the chemical elements in group 15 of the periodic table. Group 15 is also known as the nitrogen group or nitrogen family. Group 15 consists of the ...

trihalide that can adopt both molecular and polymeric structures.

Reactivity

Bismuth bromide is highly water-soluble. It is a Lewis acid and accepts bromide ions to form monomeric and oligomeric anionic complexes (bromobismuthates), e.g. iBr₆sup>3−, i₂Br₁₀sup>4−, ()_''n'' and ()_''n''.

References

Bismuth compounds Bromides Metal halides {{inorganic-compound-stub