Bismuth(III) iodide is the

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 ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...

Bi I₃. This gray-black salt is the product of the reaction of bismuth and iodine, which once was of interest in

qualitative inorganic analysis Classical qualitative inorganic analysis is a method of analytical chemistry which seeks to find the elemental composition of inorganic compounds. It is mainly focused on detecting ions in an aqueous solution, therefore materials in other forms m ...

. Bismuth(III) iodide adopts a distinctive crystal structure, with

iodide An iodide ion is I−. Compounds with iodine in formal oxidation state −1 are called iodides. In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. Worldwide, iodine deficiency ...

centres occupying a hexagonally closest-packed lattice, and bismuth centres occupying either none or two-thirds of the octahedral holes (alternating by layer), therefore it is said to occupy one third of the total octahedral holes.

Synthesis

Bismuth(III) iodide forms upon heating an intimate mixture of iodine and bismuth powder: :2Bi + 3I₂ → 2BiI₃ BiI₃ can also be made by the reaction of

bismuth oxide Bismuth(III) oxide is a compound of bismuth, and a common starting point for bismuth chemistry. It is found naturally as the mineral bismite (monoclinic) and sphaerobismoite (tetragonal, much more rare), but it is usually obtained as a by-product ...

with aqueous

hydroiodic acid Hydroiodic acid (or hydriodic acid) is a colorless liquid. It is an aqueous solution of hydrogen iodide with the chemical formula . It is a strong acid, in which hydrogen iodide is ionized completely in an aqueous solution. Concentrated aqueous ...

: :Bi₂O₃(s) + 6HI(aq) → 2BiI₃(s) + 3H₂O(l)

Reactions

Since bismuth(III) iodide is insoluble in water, an aqueous solution can be tested for the presence of Bi³⁺ ions by adding a source of iodide such as

potassium iodide Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are u ...

. A black

precipitate In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemic ...

of bismuth(III) iodide indicates a positive test. Bismuth(III) iodide forms iodobismuth(III) anions when heated with halide donors: :2 NaI + BiI₃ → Na₂ iI₅ Bismuth(III) iodide catalyzes the

Mukaiyama aldol reaction In organic chemistry, the Mukaiyama aldol addition is an organic reaction and a type of aldol reaction between a silyl enol ether () and an aldehyde () or formate (). The reaction was discovered by Teruaki Mukaiyama in 1973. His choice of reacta ...

. Bi(III) is also used in a Barbier type allylation of carbonyl compounds in combination with a reducing agent such as

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

References

{{Iodides Bismuth iodide Iodides Metal halides