Aluminum iodide is a chemical compound consisting of aluminum and iodine . Invariably, the name refers to a compound of the composition Ali Al3, formed by the reaction of aluminum and iodine  or by the action of HI on Al metal . Hexahydrate is obtained from the reaction between metallic aluminum or aluminum hydroxide with hydrogen iodide or hydroiodic acid . Like the related chlorides and bromides, Ali3Is a strong Lewis acid and will absorb water from the atmosphere. It serves as a reagent for the dissociation of certain types of CO and NO bonds . It cleaves to aryl ether and deoxygenates to epoxide .
solid ali3is dimeric, containing Al2I6, similar to AlBr 3.  The structure of the monomeric and dimeric forms is illustrated in the gas phase.  Monomer, Ali3is a triangular planar with a bond length of 2.448(6), and the bridge dimer, Al2I6Similar to Al 2 Cl 6 and Al 2 Br 6 with Al-I bond lengths of 2.456 (6) (terminal) and 2.670 (8) Al (bridging) at 430 K. The dimer is described as floppy with an equilibrium geometry of D2H .
Aluminum (I) Iodide
The name “aluminum 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 is unstable at room temperature relative to the Li triiodide:
3 Ali → Ali3+ 2 Ali
An example derivative of aluminum monoiodide is the cyclic adduct formation triethylamine, Al .4I4(NET3)4.