Zinc 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 ZnI
2. It exists both in anhydrous form and as a dihydrate. Both are white and readily absorb water from the atmosphere. It has no major application.
Preparation
It can be prepared by the direct reaction of zinc and iodine in water
or refluxing
ether:
: Zn + I
2 → ZnI
2
Absent a solvent, the elements do not combine directly at room temperature.
Structure as solid, gas, and in solution
The structure of solid ZnI
2 is unusual relative to the dichloride. While zinc centers are tetrahedrally coordinated, as in
ZnCl2, groups of four of these tetrahedra share three vertices to form “super-tetrahedra” of composition , which are linked by their vertices to form a three-dimensional structure.
These "super-tetrahedra" are similar to the
P4O10 structure.
Molecular ZnI
2 is linear as predicted by
VSEPR theory with a Zn-I bond length of 238 pm.
In aqueous solution the following have been detected: Zn(H
2O)
62+,
nI(H2O)5sup>+, tetrahedral ZnI
2(H
2O)
2, ZnI
3(H
2O)
−, and ZnI
42−.
Applications
*Zinc iodide is often used as an
x-ray
An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...
opaque penetrant in
industrial radiography
Industrial radiography is a modality of non-destructive testing that uses ionizing radiation to inspect materials and components with the objective of locating and quantifying defects and degradation in material properties that would lead to the ...
to improve the contrast between the damage and intact composite.
*United States
patent
A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...
4,109,065 describes a rechargeable aqueous zinc-halogen
cell that includes an aqueous electrolytic solution containing a zinc salt selected from the class consisting of
zinc bromide, zinc iodide, and mixtures thereof, in both positive and negative
electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or a gas). In electrochemical cells, electrodes are essential parts that can consist of a varie ...
compartments.
*In combination with
osmium tetroxide, ZnI
2 is used as a stain in electron microscopy.
*As a Lewis acid, zinc iodide catalyzes for the conversion of
methanol
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical compound and the simplest aliphatic Alcohol (chemistry), alcohol, with the chemical formula (a methyl group linked to a hydroxyl group, often ab ...
to
triptane and
hexamethylbenzene.
* It can be used as a topical antiseptic.
References
{{Iodides
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 ...
Metal halides
iodide