Editing Indium (section)

==Compounds==
{{See also|Indium chalcogenides|Category:Indium compounds}}

===Indium(III)===
[[File:Kristallstruktur Chrom(III)-chlorid.png|thumb|right|upright=1|[[Indium trichloride|InCl<sub>3</sub>]] ''(structure pictured)'' is a common compound of indium.]]
[[Indium(III) oxide]], In<sub>2</sub>O<sub>3</sub>, forms when indium metal is burned in air or when the hydroxide or nitrate is heated.<ref name="downs">{{Cite book| title = Chemistry of aluminium, gallium, indium, and thallium| author = Anthony John Downs| publisher = Springer| year = 1993| isbn = 978-0-7514-0103-5}}</ref> In<sub>2</sub>O<sub>3</sub> adopts a structure like [[alumina]] and is amphoteric, that is able to react with both acids and bases. Indium reacts with water to reproduce soluble [[indium(III) hydroxide]], which is also amphoteric; with alkalis to produce indates(III); and with acids to produce indium(III) salts:

:In(OH)<sub>3</sub> + 3&nbsp;HCl → InCl<sub>3</sub> + 3&nbsp;H<sub>2</sub>O

The analogous sesqui-chalcogenides with [[sulfur]], [[selenium]], and [[tellurium]] are also known.<ref name="Greenwood286">Greenwood and Earnshaw, p. 286</ref> Indium forms the expected [[indium halides|trihalides]]. Chlorination, bromination, and iodination of In produce colorless [[indium(III) chloride|InCl<sub>3</sub>]], [[indium(III) bromide|InBr<sub>3</sub>]], and yellow InI<sub>3</sub>. The compounds are [[Lewis acid]]s, somewhat akin to the better known aluminium trihalides. Again like the related aluminium compound, InF<sub>3</sub> is polymeric.<ref name="Greenwood263">Greenwood and Earnshaw, pp. 263–7</ref>

Direct reaction of indium with the [[pnictogen]]s produces the gray or semimetallic III–V [[semiconductor]]s. Many of them slowly decompose in moist air, necessitating careful storage of semiconductor compounds to prevent contact with the atmosphere. Indium nitride is readily attacked by acids and alkalis.<ref name="Greenwood288">Greenwood and Earnshaw, p. 288</ref>

===Indium(I)===
Indium(I) compounds are not common. The chloride, [[indium(I) bromide|bromide]], and iodide are deeply colored, unlike the parent trihalides from which they are prepared. The fluoride is known only as an unstable gas.<ref name="Greenwood270">Greenwood and Earnshaw, pp. 270–1</ref> Indium(I) oxide black powder is produced when indium(III) oxide decomposes upon heating to 700&nbsp;°C.<ref name="downs" />

===Other oxidation states===
Less frequently, indium forms compounds in oxidation state +2 and even fractional oxidation states. Usually such materials feature In–In bonding, most notably in the [[indium halides|halides]] In<sub>2</sub>X<sub>4</sub> and [In<sub>2</sub>X<sub>6</sub>]<sup>2−</sup>,<ref name="can82">{{cite journal| doi =10.1139/v82-102| title =Neutral complexes of the indium dihalides| date =1982| last1 =Sinclair| first1 =Ian| last2 =Worrall| first2 =Ian J.| journal =Canadian Journal of Chemistry| volume =60| issue =6| pages =695–698| doi-access =free}}</ref> and various subchalcogenides such as In<sub>4</sub>Se<sub>3</sub>.<ref name="Greenwood287">Greenwood and Earnshaw, p. 287</ref> Several other compounds are known to combine indium(I) and indium(III), such as In<sup>I</sup><sub>6</sub>(In<sup>III</sup>Cl<sub>6</sub>)Cl<sub>3</sub>,<ref>{{cite journal |doi = 10.1002/anie.199108241 |title = In7Cl9—A New"Old" Compound in the System In-Cl |date = 1991 |last1 = Beck |first1 = Horst Philipp |last2 = Wilhelm |first2 = Doris |journal = Angewandte Chemie International Edition in English |volume = 30 |issue = 7 |pages = 824–825}}</ref> In<sup>I</sup><sub>5</sub>(In<sup>III</sup>Br<sub>4</sub>)<sub>2</sub>(In<sup>III</sup>Br<sub>6</sub>),<ref>{{cite journal| doi =10.1002/anie.199511261| title =Synthesis, Structure, and Decay of In4Br7| date =1995| last1 =Dronskowski| first1 =Richard| journal =Angewandte Chemie International Edition in English| volume =34| issue =10| pages =1126–1128}}</ref> and In<sup>I</sup>In<sup>III</sup>Br<sub>4</sub>.<ref name="can82" />

===Organoindium compounds===
Organoindium compounds feature In–C bonds. Most are In(III) derivatives, but [[cyclopentadienylindium(I)]] is an exception. It was the first known organoindium(I) compound,<ref>{{cite journal| doi =10.1002/ange.19570692008| title =Metall-cyclopentadienyle des Indiums| date =1957| last1 =Fischer| first1 = E. O.| last2 =Hofmann| first2 = H. P.| journal =Angewandte Chemie| volume =69| issue =20| pages =639–640| bibcode =1957AngCh..69..639F| language =de}}</ref> and is polymeric, consisting of zigzag chains of alternating indium atoms and [[cyclopentadienyl complex]]es.<ref>{{cite journal | title = Synthesis, characterization and structural studies of In(C<sub>5</sub>H<sub>4</sub>Me) by x-ray diffraction and electron diffraction techniques and a reinvestigation of the crystalline state of In(C<sub>5</sub>H<sub>5</sub>) by x-ray diffraction studies |author1=Beachley O. T. |author2=Pazik J. C. |author3=Glassman T. E. |author4=Churchill M. R. |author5=Fettinger J.C. |author6=Blom R. | journal = Organometallics | year = 1988| volume = 7 | issue = 5 | pages = 1051–1059 | doi = 10.1021/om00095a007 }}</ref> Perhaps the best-known organoindium compound is [[trimethylindium]], In(CH<sub>3</sub>)<sub>3</sub>, used to prepare certain semiconducting materials.<ref>{{cite journal | doi = 10.1016/S0022-0248(02)01854-7 | title = Correlation of vapor pressure equation and film properties with trimethylindium purity for the MOVPE grown III–V compounds | year = 2003 | last1 = Shenai | first1 = Deo V. | last2 = Timmons | first2 = Michael L. | last3 = Dicarlo | first3 = Ronald L. | last4 = Lemnah | first4 = Gregory K. | last5 = Stennick | first5 = Robert S. | journal = Journal of Crystal Growth | volume = 248 | pages = 91–98 | bibcode=2003JCrGr.248...91S}}</ref><ref name="shenai2004">{{cite journal | doi = 10.1016/j.jcrysgro.2004.09.006 | title = Correlation of film properties and reduced impurity concentrations in sources for III/V-MOVPE using high-purity trimethylindium and tertiarybutylphosphine | last1 = Shenai | first1 = Deodatta V. | last2 = Timmons | first2 = Michael L. | last3 = Dicarlo | first3 = Ronald L. | last4 = Marsman | first4 = Charles J. | journal = Journal of Crystal Growth | volume = 272 | issue = 1–4 | pages = 603–608 | bibcode=2004JCrGr.272..603S | date= 2004}}</ref>