Bismuth(III) iodide is the
inorganic compound with the
formula 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 ma ...
.
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Bismuth(III) iodide adopts a distinctive crystal structure, with
iodide
An iodide ion is the ion 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 de ...
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.
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Synthesis
Bismuth(III) iodide forms upon heating an intimate mixture of iodine and bismuth powder:
:2Bi + 3I
2 → 2BiI
3
BiI
3 can also be made by the reaction of
bismuth oxide
Bismuth(III) oxide is perhaps the most industrially important compound of bismuth. It is also a common starting point for bismuth chemistry. It is found naturally as the mineral bismite (monoclinic) and sphaerobismoite (tetragonal, much more rare ...
with aqueous
hydroiodic acid
Hydroiodic acid (or hydriodic acid) is an aqueous solution of hydrogen iodide (HI). It is a strong acid, one that is ionized completely in an aqueous solution. It is colorless. Concentrated solutions are usually 48% to 57% HI.
Reactions
Hy ...
:
:Bi
2O
3(s) + 6HI(aq) → 2BiI
3(s) + 3H
2O(l)
Reactions
Since bismuth(III) iodide is insoluble in water, an aqueous solution can be tested for the presence of Bi
3+ 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 process of transforming a dissolved substance into an insoluble solid from a super-saturated solution. The solid formed is called the precipitate. In case of an inorganic chemical reaction leading ...
of bismuth(III) iodide indicates a positive test.
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]
Bismuth(III) iodide forms iodobismuth(III) anions when heated with halide donors:
[
]
:2
NaI + BiI
3 → Na
2 iI5
Bismuth(III) iodide catalyzes the
Mukaiyama aldol reaction
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 (1927–2018) in 1973. His choice of reactants allows fo ...
. 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 with the symbol Zn and atomic number 30. Zinc 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 periodi ...
or
magnesium
Magnesium is a chemical element with the 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 of the periodic ta ...
.
References
{{Iodides
Bismuth iodide
Bismuth(III) iodide is the inorganic compound with the formula 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.
Bismuth(III) iodide adopts a distinc ...
Iodides
Metal halides