Aluminium iodide

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Aluminium iodide
Ball and stick model of aluminium iodide dimer
200px
Names
Preferred IUPAC name
Aluminium iodide
Other names
Aluminium(III) iodide

Aluminum iodide
Aluminium triiodide

Aluminum triiodide
Identifiers
7784-23-8 (anhydrate) YesY
10090-53-6 (hexahydrate) YesY
ChemSpider 74202 (anhydrate) YesY
EC Number 232-054-8
Jmol 3D model Interactive image
PubChem 82222 (anhydrate)
UN number UN 3260
  • InChI=1S/Al.3HI/h;3*1H/q+3;;;/p-3 YesY
    Key: CECABOMBVQNBEC-UHFFFAOYSA-K YesY
  • InChI=1/Al.3HI/h;3*1H/q+3;;;/p-3
    Key: CECABOMBVQNBEC-DFZHHIFOAE
  • I[Al](I)I
Properties
AlI3
Molar mass 407.69495 g/mol (anhydrous)
515.786 g/mol (hexahydrate)
Appearance colorless powder
but impure samples
are often brown
Density 3.98 g/cm3 (anhydrous)
2.63 g/cm3 (hexahydrate)
Melting point 189.4 °C (372.9 °F; 462.5 K) (anhydrous)
185 °C, decomposes (hexahydrate)
Boiling point 360 °C (680 °F; 633 K) , sublimes
reacts violently (anhydrous)
soluble (hexahydrate)
Solubility in alcohol, ether soluble (hexahydrate)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Aluminium iodide is any chemical compound containing only aluminium and iodine. Invariably, the name refers to a compound of the composition AlI3, formed by the reaction of aluminium and iodine[1] or the action of HI on Al 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, AlI3 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 AlI3 is dimeric, consisting of Al2I6, similar to that of AlBr3.[3] The structure of monomeric and dimeric forms have been characterized in the gas phase.[4] The monomer, AlI3 is trigonal planar with a bond length of 2.448(6) Å, and the bridged dimer, Al2I6 at 430 K is a similar to Al2Cl6 and Al2Br6 with Al-I 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 D2h.

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[5]

3 AlI → AlI3 + 2 Al

An illustrative derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine, AI4I4(NEt3)4.

References

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