Bismuth tribromide is an

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

bismuth Bismuth is a chemical element; it has 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 nat ...

and

bromine Bromine is a chemical element; it has chemical symbol, symbol Br and atomic number 35. It is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between th ...

with the

chemical formula 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 symbols, such as pare ...

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 a repeating pattern in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of the pattern that ...

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

pyramidal A pyramid () is a structure whose visible surfaces are triangular in broad outline and converge toward the top, making the appearance roughly a pyramid in the geometric sense. The base of a pyramid can be of any polygon shape, such as triangu ...

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

group 15 , - ! colspan=2 style="text-align:left;" , ↓ Period , - ! 2 , , - ! 3 , , - ! 4 , , - ! 5 , , - ! 6 , , - ! 7 , , - , colspan="2", ---- ''Legend'' A pnictogen ( or ; from "to choke" and -gen, "generator") is any ...

trihalide that can adopt both molecular and polymeric structures.

Reactivity

Bismuth bromide is highly water-soluble. It is a

Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any ...

and accepts bromide ions to form monomeric and oligomeric anionic complexes (bromobismuthates), e.g. iBr₆sup>3−, i₂Br₁₀sup>4−, ()_''n'' and ()_''n''.

References

{{DEFAULTSORT:Bismuth Bromide Bismuth compounds Bromides Metal halides