AlI3

Aluminum iodide, often written as AlI3, is an ionic compound formed between aluminum and iodine. In its anhydrous form, it is a colorless solid. When exposed to air, particularly moist air, it readily hydrolyzes to form aluminum oxide and hydrogen iodide. This reactivity makes it challenging to handle and store in its pure, anhydrous state. AlI3 is soluble in several organic solvents, including ethanol and acetone. It can be prepared by the direct reaction of aluminum metal with iodine, often in the presence of a catalyst or under specific temperature conditions. Another method involves the reaction of aluminum trichloride with sodium iodide. The structure of solid aluminum iodide is polymeric, featuring bridging iodide ligands. In the gaseous state, it exists as discrete AlI3 molecules. Aluminum iodide finds some limited applications as a Lewis acid catalyst in organic synthesis. Its hygroscopic nature and tendency to decompose upon exposure to moisture necessitate careful handling and storage, typically under an inert atmosphere.