| Names | |
|---|---|
| IUPAC name Iron(II) iodide | |
| Other names Ferrous iodide | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider | |
| ECHA InfoCard | 100.029.119 |
| EC Number |
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| UNII | |
| |
| |
| Properties | |
| FeI2 | |
| Molar mass | 309.65 g/mol |
| Appearance | White to off-white or grey[1] powder |
| Density | 5.315 g/cm3 |
| Melting point | 587 °C (1,089 °F; 860 K) |
| Boiling point | 827 °C (1,521 °F; 1,100 K) |
| soluble | |
| +13,600·10−6 cm3/mol | |
| Related compounds | |
Otheranions | Iron(II) fluoride Iron(II) chloride Iron(II) bromide |
Othercations | Manganese(II) iodide Cobalt(II) iodide |
| Iron(III) iodide | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Iron(II) iodide is aninorganic compound with thechemical formula FeI2.[1][2] It is used as a catalyst in organic reactions.
Iron(II) iodide can be synthesised by the reaction ofiron withiodine at 500 °C:[1][3]
This is in contrast to the other iron(II) halides, which are best prepared by reaction of heated iron with the appropriatehydrohalic acid.
Alternatively, the synthesis can be carried out by treating freshly reduced iron with concentratedhydriodic acid under anitrogen atmosphere inmethanol. The initially obtained hexamethanol solvate is then thermally decomposed to anhydrous iodide:
Extremely finely divided iron(II) iodide is obtained by thermal decomposition of tetracarbonyldiiodidoiron(II) (Fe(CO)4I2).[3]
In contrast to the ferrous fluoride, chloride and bromide, which form known hydrates, the diiodide is speculated to form a stable tetrahydrate but it not been characterized directly.[4]
Iron(II) iodide is a hygroscopic red-violet to black solid that is soluble inwater,ethanol anddiethyl ether. Rapid oxidation occurs in solution and in moist air.[5] It turns whitish when exposed to air. The solution in water is colorless.
Dissolving iron metal inhydroiodic acid is another route to aqueous solutions of iron(II) iodide. Crystalline hydrates precipitate from these solutions.[1][clarification needed]
Iron(II) iodide adopts the samecrystal structure ascadmium iodide (CdI2).[1] It crystallizes in thetrigonal crystal system of thecadmium hydroxide type with thespace groupP3m1 (space group no. 164) andlattice constantsa = 404 pm,c = 675 pm.[3][6]
Iron(II) iodide is used as an ingredient inhomeopathic medicines. In the field of application it is known asFerrum jodatum. However, the attributed effect, particularly against glandular diseases, has not been scientifically confirmed.
It is also used for the production of alkali iodides.[6]
