Aluminium iodide

From Wikipedia, the free encyclopedia
Jump to: navigation, search
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
CAS number 7784-23-8 (anhydrate) YesY
10090-53-6 (hexahydrate)
ChemSpider 74202 (anhydrate) YesY
EC number 232-054-8
Jmol-3D images 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 noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY verify (what isYesY/N?)
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.