Editing Iron (section)

===Binary compounds===
====Oxides and sulfides====
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| caption1 = Ferrous or iron(II) oxide, {{chem2|FeO}}
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| caption2 = Ferric or iron(III) oxide {{chem2|Fe2O3}}
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| caption3 = Ferrosoferric or iron(II,III) oxide {{chem2|Fe3O4}}
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Iron forms various [[iron oxide|oxide and hydroxide compounds]]; the most common are [[iron(II,III) oxide]] (Fe<sub>3</sub>O<sub>4</sub>), and [[iron(III) oxide]] (Fe<sub>2</sub>O<sub>3</sub>). [[Iron(II) oxide]] also exists, though it is unstable at room temperature. Despite their names, they are actually all [[non-stoichiometric compound]]s whose compositions may vary.{{sfn|Greenwood|Earnshaw|1997|p=1079}} These oxides are the principal ores for the production of iron (see [[bloomery]] and blast furnace). They are also used in the production of [[Ferrite (magnet)|ferrites]], useful [[magnetic storage]] media in computers, and pigments. The best known sulfide is [[iron pyrite]] (FeS<sub>2</sub>), also known as fool's gold owing to its golden luster.<ref name="HollemanAF" /> It is not an iron(IV) compound, but is actually an iron(II) [[polysulfide]] containing Fe<sup>2+</sup> and {{chem|S|2|2-}} ions in a distorted [[sodium chloride]] structure.{{sfn|Greenwood|Earnshaw|1997|p=1079}}

[[File:Pourbaix Diagram of Iron.svg|thumb|right|[[Pourbaix diagram]] of iron]]

====Halides====
[[File:Iron(III) chloride hexahydrate.jpg|thumb|upright=0.7|alt=Some canary-yellow powder sits, mostly in lumps, on a laboratory watch glass.|Hydrated iron(III) chloride (ferric chloride)]]
The binary ferrous and ferric [[halide]]s are well-known. The ferrous halides typically arise from treating iron metal with the corresponding [[hydrohalic acid]] to give the corresponding hydrated salts.<ref name="HollemanAF" />
:Fe + 2 HX → FeX<sub>2</sub> + H<sub>2</sub> (X = F, Cl, Br, I)
Iron reacts with fluorine, chlorine, and bromine to give the corresponding ferric halides, [[ferric chloride]] being the most common.{{sfn|Greenwood|Earnshaw|1997|pp=1082–84}}
:2 Fe + 3 X<sub>2</sub> → 2 FeX<sub>3</sub> (X = F, Cl, Br)
[[Ferric iodide]] is an exception, being thermodynamically unstable due to the oxidizing power of Fe<sup>3+</sup> and the high reducing power of I<sup>−</sup>:{{sfn|Greenwood|Earnshaw|1997|pp=1082–84}}
:2 I<sup>−</sup> + 2 Fe<sup>3+</sup> → I<sub>2</sub> + 2 Fe<sup>2+</sup> (E<sup>0</sup> = +0.23 V)

Ferric iodide, a black solid, is not stable in ordinary conditions, but can be prepared through the reaction of [[iron pentacarbonyl]] with [[iodine]] and [[carbon monoxide]] in the presence of [[hexane]] and light at the temperature of −20 °C, with oxygen and water excluded.{{sfn|Greenwood|Earnshaw|1997|pp=1082–84}} Complexes of ferric iodide with some soft bases are known to be stable compounds.<ref>Siegfried Pohl, Ulrich Bierbach, Wolfgang Saak; "FeI3SC(NMe2)2, a Neutral Thiourea Complex of Iron(III) Iodide", Angewandte Chemie International Edition in English (1989) 28 (6), 776–777. https://doi.org/10.1002/anie.198907761</ref><ref>Nicholas A. Barnes, Stephen M.Godfrey, Nicholas Ho, Charles A.McAuliffe, Robin G.Pritchard; "Facile synthesis of a rare example of an iron(III) iodide complex, [FeI3(AsMe3)2], from the reaction of Me3AsI2 with unactivated iron powder", Polyhedron (2013) 55, 67–72. https://doi.org/10.1016/j.poly.2013.02.066</ref>