Aluminium iodide
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| Names | |
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| Preferred IUPAC name
Aluminium iodide | |
| Other names
Aluminium(III) iodide
Aluminum iodide | |
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3D model (JSmol)
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| ChemSpider |
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| ECHA InfoCard | 100.029.140 |
| EC Number |
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PubChem CID
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| UN number | UN 3260 |
CompTox Dashboard (EPA)
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| 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).
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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
- ^ G. W. Watt, J. L. Hall (1953). Inorganic Syntheses. Vol. IV. pp. 117–119.
- ^ 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.
- ^ 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.219.2.88.26320. ISSN 0044-2968.
- ^ 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.
- ^ 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.
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