Aluminium iodide

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Aluminium iodide is a chemical compound containing aluminium and iodine. Invariably, the name refers to a compound of the composition $Template:Chem/link$ Script error: No such module "Check for unknown parameters"., formed by the reaction of aluminium and iodine^[1] or the action of [[Hydrogen iodide|Template:Chem/link]] on Template:Chem/link 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, $Template:Chem/link$ Script error: No such module "Check for unknown parameters". is a strong Lewis acid and will absorb water from the atmosphere. It is employed as a reagent for the scission of certain kinds of C-O and N-O bonds. It cleaves aryl ethers and deoxygenates epoxides.^[2]

Structure

Solid $Template:Chem/link$ Script error: No such module "Check for unknown parameters". is dimeric, consisting of Template:Chem/link, similar to that of [[aluminium tribromide|Template:Chem/link]].^[3] The structure of monomeric and dimeric forms have been characterized in the gas phase.^[4] The monomer, $Template:Chem/link$ Script error: No such module "Check for unknown parameters"., is trigonal planar with a bond length of 2.448(6) Å, and the bridged dimer, Template:Chem/link, at 430 K is a similar to [[Aluminium chloride|Template:Chem/link]] and [[Aluminium bromide|Template:Chem/link]] with Template:Chem2 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

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File:06. Директна синтеза на алуминиум јодид.webm

Experiment showing a direct synthesis of aluminum iodide. Few drops of water are added to a homogenised mixture of aluminum powder and powdered iodine. After short time (an induction period) a vigorous reaction occurs followed by emission of intense colored vapors. The purple vapours are due to evaporation of iodine as a consequence of increased temperature of the system, and the brown ones are probably due to smoke of an adduct of the reaction product with excess of iodine. The exergonic reaction Template:Chem2 is at the origin of the phenomenon observed.

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:^[5]