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Aluminium iodide

Names
Preferred IUPAC name Aluminium iodide
Other names Aluminium(III) iodide Aluminum iodide Aluminium triiodide Aluminum triiodide
Identifiers
CAS Number	7784-23-8 (anhydrate) 10090-53-6 (hexahydrate)
3D model (JSmol)	Interactive image dimer: Interactive image
ChemSpider	74202 (anhydrate)
ECHA InfoCard	100.029.140
EC Number	232-054-8
PubChem CID	82222 (anhydrate)
UNII	L903Z8J9VR (anhydrate) VWS43EUO9V (hexahydrate)
UN number	UN 3260
CompTox Dashboard (EPA)	DTXSID0064838
InChI Key: CECABOMBVQNBEC-UHFFFAOYSA-K Key: CECABOMBVQNBEC-DFZHHIFOAE
SMILES I(I)I dimer: I1(I)(1)(I)I
Properties
Chemical formula	AlI3, AlI3·6H2O (hexahydrate)
Molar mass	407.695 g/mol (anhydrous) 515.786 g/mol (hexahydrate)
Appearance	white (anhydrous) or yellow powder (hexahydrate)
Density	3.98 g/cm (anhydrous) 2.63 g/cm (hexahydrate)
Melting point	188.28 °C (370.90 °F; 461.43 K) (anhydrous) 185 °C, decomposes (hexahydrate)
Boiling point	382 °C (720 °F; 655 K) anhydrous, sublimes
Solubility in water	very soluble, partial hydrolysis
Solubility in alcohol, ether	soluble (hexahydrate)
Structure
Crystal structure	Monoclinic, mP16
Space group	P21/c, No. 14
Lattice constant	a = 1.1958 nm, b = 0.6128 nm, c = 1.8307 nmα = 90°, β = 90°, γ = 90°
Formula units (Z)	8
Thermochemistry
Heat capacity (C)	98.7 J/(mol·K)
Std molar entropy (S298)	195.9 J/(mol·K)
Std enthalpy of formation (ΔfH298)	-302.9 kJ/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). N verify (what is  ?) Infobox references

Aluminium iodide is a chemical compound containing aluminium and iodine. Invariably, the name refers to a compound of the composition AlI
₃, formed by the reaction of aluminium and iodine 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, AlI
₃ 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.

Structure

Solid AlI
₃ is dimeric, consisting of Al
₂I
₆, similar to that of AlBr
₃. The structure of monomeric and dimeric forms have been characterized in the gas phase. The monomer, AlI
₃, is trigonal planar with a bond length of 2.448(6) Å, and the bridged dimer, Al
₂I
₆, at 430 K is a similar to Al
₂Cl
₆ and Al
₂Br
₆ 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 D_2h.

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:

${\displaystyle {\ce {3AlI -> AlI3 + 2Al}}}$

An illustrative derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine, Al
₄I
₄(NEt
₃)
₄.

References

1. ^ Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, Florida: CRC Press. p. 4.45. ISBN 1-4398-5511-0.
2. ^ Perry, Dale L. (19 April 2016). Handbook of Inorganic Compounds, Second Edition. CRC Press. p. 8. ISBN 978-1-4398-1462-8.
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.219.2.88.26320. S2CID 101603507.
4. Watt, George W; Hall, James L; Taylor, William Lloyd; Kleinberg, Jacob (1953). "Aluminum Iodide". Inorganic Syntheses. Vol. 4. pp. 117–119. doi:10.1002/9780470132357.ch39. ISBN 9780470132357.
5. Gugelchuk, M. (2004). "Aluminum Iodide". In L. Paquette (ed.). Encyclopedia of Reagents for Organic Synthesis. New York: J. Wiley & Sons. doi:10.1002/047084289X.ra083. ISBN 0471936235.
6. Hargittai, Magdolna; Réffy, Balázs; Kolonits, Mária (2006). "An Intricate Molecule: Aluminum Triiodide. Molecular Structure of AlI₃and Al₂I₆ from Electron Diffraction and Computation". The Journal of Physical Chemistry A. 110 (10): 3770–3777. doi:10.1021/jp056498e. PMID 16526661.
7. Dohmeier, C.; Loos, D.; Schnöckel, H. (1996). "Aluminum(I) and Gallium(I) Compounds: Syntheses, Structures, and Reactions". Angewandte Chemie International Edition. 35 (2): 129–149. doi:10.1002/anie.199601291.

External links

• Media related to Aluminium iodide at Wikimedia Commons

• Iodides
• Aluminium compounds
• Metal halides