Aluminium iodide

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Aluminium iodide
Ball and stick model of aluminium iodide dimer
Jodid hlinitý.PNG
Preferred IUPAC name
Aluminium iodide
Other names
Aluminium(III) iodide

Aluminum iodide
Aluminium triiodide

Aluminum triiodide
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
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).
N 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]


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[edit]

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.


  1. ^ G. W. Watt; J. L. Hall (1953). Inorganic Syntheses IV. pp. 117–119. 
  2. ^ M. Gugelchuk (2004). Aluminum Iodide, in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette). New York: J. Wiley & Sons. doi:10.1002/047084289X.ra083. 
  3. ^ Troyanov, Sergey I.; Krahl, Thoralf; Kemnitz, Erhard (2004). "Crystal structures of GaX3(X= Cl, Br, I) and AlI3". Zeitschrift für Kristallographie 219 (2-2004): 88–92. doi:10.1524/zkri. ISSN 0044-2968. 
  4. ^ Hargittai, Magdolna; Réffy, Balázs; Kolonits, Mária (2006). "An Intricate Molecule: Aluminum Triiodide. Molecular Structure of AlI3and Al2I6from Electron Diffraction and Computation". The Journal of Physical Chemistry A 110 (10): 3770–3777. doi:10.1021/jp056498e. ISSN 1089-5639. 
  5. ^ Dohmeier, C.; Loos, D.; Schnöckel, H. (1996). "Aluminum(I) and Gallium(I) Compounds: Syntheses, Structures, and Reactions". Angewandte Chemie International Edition 35: 129–149. doi:10.1002/anie.199601291.