Aluminium iodide

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[Al](I)I; dimer: I[Al-]1(I)[I+][Al-]([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/cm3 (anhydrous) 2.63 g/cm3 (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 nm α = 90°, β = 90°, γ = 90°
Formula units (Z)	8
Thermochemistry
Heat capacity (C)	98.7 J/(mol·K)
Std molar; entropy (S⦵298)	195.9 J/(mol·K)
Std enthalpy of; formation (ΔfH⦵298)	−302.9 kJ/mol
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Aluminium iodide is the inorganic compound with the composition AlI₃. It also exists a various hydrates formed by exposure of the anhydrous material to water.^[4] For example the hexahydrate is obtained from a reaction between metallic aluminum or aluminum hydroxide with 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.^[5]

Preparation

Aluminium iodide is formed by the reaction of aluminium and iodine^[6] or the action of HI on Al metal.

Structure

Solid $AlI 3$ is dimeric, consisting of Al
₂I
₆, similar to that of AlBr
₃.^[3] The structure of monomeric and dimeric forms have been characterized in the gas phase.^[7] 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:^[8]

3 AlI \to AlI 3 + 2 Al

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

References

^ ^a ^b ^c ^d ^e ^f 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.
^ ^a ^b Perry, Dale L. (19 April 2016). Handbook of Inorganic Compounds, Second Edition. CRC Press. p. 8. ISBN 978-1-4398-1462-8.
^ ^a ^b Troyanov, Sergey I.; Krahl, Thoralf; Kemnitz, Erhard (2004). "Crystal structures of $GaX 3 (X= Cl, Br, I)$ and $AlI 3$ ". Zeitschrift für Kristallographie. 219 (2–2004): 88–92. doi:10.1524/zkri.219.2.88.26320. S2CID 101603507.
^ Schmidt, Horst; Hennings, Erik; Voigt, Wolfgang (2014). "Crystal structures of hydrates of simple inorganic salts. III. Water-rich aluminium halide hydrates: AlCl₃·15H₂O, AlBr₃·15H₂O, AlI₃·15H₂O, AlI₃·17H₂O and AlBr₃·9H₂O". Acta Crystallographica Section C Structural Chemistry. 70 (9): 882–888. doi:10.1107/S2053229614014302. PMID 25186362.
^ 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.
^ 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. {{cite book}}: ISBN / Date incompatibility (help)
^ Hargittai, Magdolna; Réffy, Balázs; Kolonits, Mária (2006). "An Intricate Molecule: Aluminum Triiodide. Molecular Structure of $AlI 3$ and $Al 2 I 6$ from Electron Diffraction and Computation". The Journal of Physical Chemistry A. 110 (10): 3770–3777. doi:10.1021/jp056498e. PMID 16526661.
^ 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

[b92-1] ^ ^a ^b ^c ^d ^e ^f 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.

[Perry2016-2] Perry, Dale L. (19 April 2016). Handbook of Inorganic Compounds, Second Edition. CRC Press. p. 8. ISBN 978-1-4398-1462-8.

[TroyanovKrahl2004-3] Troyanov, Sergey I.; Krahl, Thoralf; Kemnitz, Erhard (2004). "Crystal structures of $GaX 3 (X= Cl, Br, I)$ and $AlI 3$ ". Zeitschrift für Kristallographie. 219 (2–2004): 88–92. doi:10.1524/zkri.219.2.88.26320. S2CID 101603507.

[4] Schmidt, Horst; Hennings, Erik; Voigt, Wolfgang (2014). "Crystal structures of hydrates of simple inorganic salts. III. Water-rich aluminium halide hydrates: AlCl₃·15H₂O, AlBr₃·15H₂O, AlI₃·15H₂O, AlI₃·17H₂O and AlBr₃·9H₂O". Acta Crystallographica Section C Structural Chemistry. 70 (9): 882–888. doi:10.1107/S2053229614014302. PMID 25186362.

[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] 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. {{cite book}}: ISBN / Date incompatibility (help)

[HargittaiRéffy2006-7] Hargittai, Magdolna; Réffy, Balázs; Kolonits, Mária (2006). "An Intricate Molecule: Aluminum Triiodide. Molecular Structure of $AlI 3$ and $Al 2 I 6$ from Electron Diffraction and Computation". The Journal of Physical Chemistry A. 110 (10): 3770–3777. doi:10.1021/jp056498e. PMID 16526661.

[8] 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.

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