Aluminium iodide is a
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
containing
aluminium
Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...
and
iodine
Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...
. Invariably, the name refers to a compound of the composition , formed by the reaction of aluminium and iodine or the action of
on metal. The hexahydrate is obtained from a reaction between metallic aluminum or
aluminum hydroxide with
hydrogen iodide or
hydroiodic acid. Like the related chloride and bromide, is a strong
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 will absorb water from the atmosphere. It is employed as a
reagent
In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...
for the scission of certain kinds of C-O and N-O bonds. It cleaves aryl
ether
In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R� ...
s and deoxygenates
epoxides.
Structure
Solid is dimeric, consisting of , similar to that of
.
The structure of monomeric and dimeric forms have been characterized in the gas phase.
The monomer, , is trigonal planar with a bond length of 2.448(6) Å, and the bridged dimer, , at 430 K is a similar to
and
with bond lengths of 2.456(6) Å (terminal) and 2.670(8) Å (bridging). The dimer is described as floppy with an equilibrium geometry of D
2h.
Aluminium(I) iodide
The name "aluminium iodide" is widely assumed to describe the triiodide or its dimer. In fact, a monoiodide also enjoys a role in the Al–I system, although the compound AlI is unstable at room temperature relative to the triiodide:
:
An illustrative derivative of aluminium monoiodide is the cyclic
adduct
In chemistry, an adduct (; alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components. The resultant is ...
formed with
triethylamine, .
References
External links
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{{Use dmy dates, date=March 2018
Iodides
iodide
Metal halides