Iron(II) iodide
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| IUPAC name
Iron(II) iodide
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| Other names
Ferrous iodide
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.029.119 |
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PubChemCID
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| UNII | |
CompTox Dashboard(EPA)
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| 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 | |
| +13,600·10−6cm3/mol | |
| Related compounds | |
Otheranions
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Iron(II) fluoride Iron(II) chloride Iron(II) bromide |
Othercations
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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).
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Iron(II) iodideis aninorganic compoundwith thechemical formulaFeI2.[1][2]It is used as a catalyst in organic reactions.
Preparation
[edit]Iron(II) iodide can be synthesised by the reaction ofironwithiodineat 500 °C:[1][3]
- Fe + I2→ FeI2
This is in contrast to the other iron(II) halides, which are best prepared by reaction of heated iron with the appropriatehydrohalic acid.
- Fe + 2 HX → FeX2+ H2
Alternatively, the synthesis can be carried out by treating freshly reduced iron with concentratedhydriodic acidunder anitrogenatmosphere inmethanol.The initially obtained hexamethanol solvate is then thermally decomposed to anhydrous iodide:
- Fe + 2 HI + 6 MeOH → FeI2·6MeOH + H2
- FeI2·6 MeOH → FeI2+ 6 MeOH
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]
Chemical properties
[edit]Iron(II) iodide is a hygroscopic red-violet to black solid that is soluble inwater,ethanolanddiethyl 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 acidis another route to aqueous solutions of iron(II) iodide. Crystalline hydrates precipitate from these solutions.[1][clarification needed]
Physical properties
[edit]Iron(II) iodide adopts the samecrystal structureascadmium iodide(CdI2).[1]It crystallizes in thetrigonal crystal systemof thecadmium hydroxidetype with thespace groupP3m1(space group no. 164) andlattice constantsa= 404 pm,c= 675 pm.[3][6]
Applications
[edit]Iron(II) iodide is used as an ingredient inhomeopathicmedicines. 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]
See also
[edit]- Iron(III) iodide,FeI3,unstable
References
[edit]- ^abcdeGreenwood, Norman N.;Earnshaw, Alan (1997).Chemistry of the Elements(2nd ed.).Butterworth-Heinemann.pp. 1083–1084.ISBN978-0-08-037941-8.
- ^University of Akron Chemical DatabaseArchived2012-12-12 atarchive.today
- ^abcHandbuch der präparativen anorganischen Chemie. 3(3., umgearb. Aufl ed.). Stuttgart: Enke. 1981.ISBN978-3-432-87823-2.
- ^Wren, J.C; Glowa, G.A; Merritt, J (1999). "Corrosion of stainless steel by gaseous I2".Journal of Nuclear Materials.265(1–2): 161–177.doi:10.1016/s0022-3115(98)00504-2.ISSN0022-3115.
- ^Lautenschläger, Karl-Heinz; Schröter, Werner; Wanninger, Andrea (2007).Taschenbuch der Chemie(20., überarb. u. erw. Aufl., [Ausg. mit CD-ROM] ed.). Frankfurt am Main: Deutsch.ISBN978-3-8171-1760-4.
- ^abAns, Jan d'; Ans, Jan d' (1998).Elemente, anorganische Verbindungen und Materialien.Taschenbuch für Chemiker und Physiker / D'Ans (4., neubearb. u. rev. Aufl ed.). Ort nicht ermittelbar: Verlag nicht ermittelbar.ISBN978-3-540-60035-0.