Iron(III) iodide is an inorganic compound with the chemical formula FeI3. It is a thermodynamically unstable compound that is difficult to prepare. Nevertheless, iron(III) iodide has been synthesised in small quantities in the absence of air and water.[1]
Names | |
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IUPAC name
Iron(III) iodide
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Other names
Ferric iodide
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Identifiers | |
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3D model (JSmol)
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ChemSpider |
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PubChem CID
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CompTox Dashboard (EPA)
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Properties | |
FeI3 | |
Molar mass | 436.56 g/mol |
Appearance | Black solid |
decomposes | |
Solubility | sparingly soluble in dichloromethane |
Related compounds | |
Other anions
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FeF3, FeCl3, FeBr3 |
Other cations
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ScI3, TiI3, VI3, MoI3, WI3, RhI3, BiI3 |
Related compounds
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FeI2 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
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Iron(III) and iodide tend to undergo a redox reaction[1] in which Fe3+ is reduced to Fe2+ and I− is oxidised to I2. This reaction can be avoided and iron(III) iodide can be synthesised by a photochemical reaction. Iron pentacarbonyl reacts with excess iodine in hexane under argon, releasing carbon monoxide and forming the complex diiodotetracarbonyliron(II), Fe(CO)4I2, as a light red solution.[1][2]
This complex then undergoes oxidative photodecarbonylation at −20 °C in the presence of further iodine and actinic light. A black film of FeI3 is deposited as further carbon monoxide is evolved.[1][2]
Iron(III) iodide is prone to light-induced decomposition to iron(II) iodide and iodine.[2][3][4]
Donor solvents such as tetrahydrofuran, acetonitrile, pyridine and water also promote this reaction: iron(III) iodide is extremely hygroscopic. It is sparingly soluble in dichloromethane. It reacts with iodide to form the tetraiodoferrate(III) ion.[2]
Iron(III) iodide undergoes ligand exchange or metathesis with certain alkyl chlorides to reversibly form iron(III) chloride and the corresponding alkyl iodides.[2]
Adducts of FeI3 are well known. An orange complex can be prepared from FeI2 and I2 in the presence of thiourea.[5][6] Iron powder reacts with iodine-containing proligands to also give adducts of ferric iodide.[7]