Gold(III) chloride: Difference between revisions

{{short description|Chemical compound}}

{{About-distinguish|the trichloride|chloroauric acid}}

{{good article}}

{{Use British English|date=June 2021}}

{{Chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 443849746

| ImageFile1 = AuCl3 structure.svg

| ImageSize1 =

| ImageCaption1 =

| ImageFile2 = Gold(III)-chloride-dimer-3D-balls.png

| ImageSize2 =

| ImageCaption2 = [[Ball-and-stick model]] of AuCl₃

| ImageFile3 = Gold(III)-chloride-xtal-3D-SF-B.png

| ImageSize3 =

| ImageCaption3 = Crystal structure of AuCl₃

| IUPACName = Gold(III) trichloride

| OtherNames = Auric chloride<br />Gold trichloride

|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 24244

| PubChem = 26030

| SMILES = Cl[Au-]1(Cl)[Cl+][Au-]([Cl+]1)(Cl)Cl <!-- [Cl-][Au+3]1([Cl-])[Cl-][Au+3]([Cl-]1)([Cl-])[Cl-] and Cl[Au+3]1(Cl)[Cl-3][Au+3]([Cl-3]1)(Cl)Cl have the right structure, but in those SMILES, the gold isn't in the +III oxidation state. -->

| CASNo_Ref = {{cascite|correct|CAS}}

| RTECS = MD5420000

}}

|Section2={{Chembox Properties

| Formula = {{chem2|AuCl3}}<br />(exists as {{chem2|Au2Cl6}})

| MolarMass = 606.6511&nbsp;g/mol

| Appearance = Red crystals (anhydrous); golden, yellow crystals (monohydrate)<ref name="wiberg_holleman"/>

| Density = 4.7&nbsp;g/cm³

| Solubility = 68&nbsp;g/100 ml (20 °C)

| SolubleOther = soluble in [[diethyl ether|ether]] and [[ethanol]], slightly soluble in liquid [[ammonia]], insoluble in [[benzene]]

| MeltingPtC = 160

| MeltingPt_notes = (decomposes)

| MagSus = −112·10⁻⁶ cm³/mol

}}

|Section3={{Chembox Structure

| Coordination = Square planar

| CrystalStruct = [[monoclinic]]

| SpaceGroup = P2₁/C

| PointGroup =

| LattConst_a = 6.57 Å

| LattConst_b = 11.04 Å

| LattConst_c = 6.44 Å

| LattConst_alpha =

| LattConst_beta = 113.3

| LattConst_gamma =

| LattConst_ref =<ref name="crys" />

}}

| Section4 = {{Chembox Thermochemistry

| Thermochemistry_ref =

| HeatCapacity =

| Entropy =

| DeltaHform = −117.6&nbsp;kJ/mol<ref>{{Cite book |title=CRC Handbook of Chemistry and Physics: A Ready-reference Book of Chemical and Physical Data |date=2016 |editor-first1=William M.|editor-last1= Haynes|editor-first2= David R.|editor-last2= Lide|editor-first3= Thomas J.|editor-last3= Bruno |isbn=978-1-4987-5428-6 |edition=95th |location=Boca Raton, Florida |oclc=930681942 |page=5-5}}</ref>

| DeltaGfree =

| DeltaHcombust =

| DeltaHfus =

| DeltaHvap =

| DeltaHsublim =

| HHV =

| LHV =

}}

|Section7={{Chembox Hazards

| Hazards_ref =<ref name=sds>{{cite web|title =Gold Chloride|url=https://www.americanelements.com/gold-chloride-13453-07-1|publisher = [[American Elements]]|access-date = July 22, 2019}}</ref>

| ExternalSDS =

| GHSPictograms = {{GHS07}}

| GHSSignalWord = Warning

| HPhrases = {{H-phrases|315|319|335}}

| PPhrases = {{P-phrases|261|264|271|280|302+352|305+351+338}}

| MainHazards = Irritant

}}

|Section8={{Chembox Related

| OtherAnions = [[Gold(III) fluoride]]<br />[[Gold(III) bromide]]

| OtherCations = [[Gold(I) chloride]]<br />[[Silver(I) chloride]]<br />[[Platinum(II) chloride]]<br />[[Mercury(II) chloride]]}}

'''Gold(III) chloride''', traditionally called '''auric chloride''', is an [[inorganic compound]] of [[gold]] and [[chlorine]] with the [[molecular formula]] {{chem2|Au2[[Chloride|Cl]]6}}. The "III" in the name indicates that the gold has an [[oxidation state]] of +3, typical for many gold compounds. It has two forms, the monohydrate (AuCl₃·H₂O) and the anhydrous form, which are both [[hygroscopic]] and light-sensitive solids. This compound is a [[Dimer (chemistry)|dimer]] of {{chem2|AuCl3}}. This compound has a few uses, such as an oxidizing agent and for [[Catalysis|catalyzing]] various [[Organic chemistry|organic reactions]].

{{chem2|AuCl3}} exists as a [[bridging ligand|chloride-bridged]] [[Wiktionary:dimer|dimer]] both as a [[solid]] and [[vapour]], at least at low temperatures.<ref name="crys">{{cite journal | author = E. S. Clark | author2 = D. H. Templeton | author3 = C. H. MacGillavry | year = 1958 | title = The crystal structure of gold(III) chloride | journal = [[Acta Crystallogr.]] | volume = 11 | issue = 4| pages = 284–288 | doi = 10.1107/S0365110X58000694 | url = http://scripts.iucr.org/cgi-bin/paper?S0365110X58000694 | access-date = 2010-05-21| doi-access = free }}</ref> [[Gold(III) bromide]] behaves analogously.<ref name="wiberg_holleman"/> The structure is similar to that of [[iodine(III) chloride]].

Each gold center is [[square planar]] in gold(III) chloride, which is typical of a metal complex with a [[d electron count|d⁸ electron count]]. The bonding in {{chem2|AuCl3}} is considered somewhat [[covalent bond|covalent]].<ref name="wiberg_holleman"/><!--, reflecting the high oxidation state and relatively high (for a metal) [[electronegativity]] of gold. So Au(II) is less covalent?--> <!--Reply to comment: yes. Think about how you can't get oxo compounds of most low oxidation state transition metals but can with higher OS.-->

==Properties==

Gold(III) chloride is a [[diamagnetic]] light-sensitive red crystalline solid that forms the orange monohydrate, AuCl₃ · H₂O; the anhydrous and monohydrate are both [[hygroscopic]]. The anhydrous form absorbs moisture from the air to form the monohydrate which can be reversed by the addition of [[thionyl chloride]].<ref name="encyclo" />

Gold(III) chloride was first prepared in 1666 by [[Robert Boyle]] by the reaction of metallic gold and [[chlorine]] gas at 180 °C:<ref name="wiberg_holleman">{{Cite book

| author1 = Egon Wiberg | author2 = Nils Wiberg | author3 = A. F. Holleman | year = 2001 | title = Inorganic Chemistry| edition = 101 | publisher = [[Academic Press]]| isbn = 978-0-12-352651-9| pages = 1286–1287

}}</ref><ref>{{cite book |author1=Robert Boyle |author1-link=Robert Boyle |title=The origine of formes and qualities |date=1666 |page=370 |url=http://name.umdl.umich.edu/A29017.0001.001 |language=en}}</ref><ref>{{cite journal |author1=Thomas Kirke Rose |title=The dissociation of chloride of gold |journal=Journal of the Chemical Society, Transactions |date=1895 |volume=67 |pages=881–904 |doi=10.1039/CT8956700881 |url=https://zenodo.org/record/1784163 |language=en}}</ref>

:{{chem2|2 Au + 3 Cl2 → Au2Cl6}}

This method is the most common method of preparing gold(III) chloride. It can also be prepared by reacting gold powder with [[iodine monochloride]]:<ref name="encyclo" />

:2 Au + 6 ICl → 2 AuCl₃ + 3 I₂

The [[Halogenation|chlorination reaction]] can be conducted in the presence of [[tetrabutylammonium chloride]], the product being the [[lipophilic]] salt tetrabutylammonium tetrachloraurate.<ref>{{cite journal |doi=10.1071/C97029|title=Reduction of &#91;NBu4&#93;&#91;AuCl4&#93; to &#91;NBu4&#93;&#91;AuCl2&#93; with Sodium Acetylacetonate|year=1997|last1=Buckley|first1=Robbie W.|last2=Healy|first2=Peter C.|last3=Loughlin|first3=Wendy A.|journal=[[Australian Journal of Chemistry]]|volume=50|issue=7|page=775}}</ref>

Another method of preparation is via [[chloroauric acid]], which is obtained by first dissolving the gold powder in [[aqua regia]] to give chloroauric acid:<ref>{{cite book |doi=10.1002/9780470132357.ch4|chapter=Gold Powder and Potassium Tetrabromoaurate(III)|series=[[Inorganic Syntheses]]|year=1953|volume=4|last1=Block|first1=B. P.|title=Inorganic Syntheses |pages=14–17|isbn=9780470132357}}</ref>

:{{chem2|Au + HNO3 + 4 HCl → H[AuCl4] + 2 H2O + NO}}

The resulting chloroauric acid is subsequently heated in an inert atmosphere at around 100&nbsp;°C to give {{chem2|Au2Cl6}}:<ref name="decomp">{{cite journal |author1=Ya-jie Zheng |author2=Wei Guo |author3=Meng Bai |author4=Xing-wen Yang |title=Preparation of chloroauric acid and its thermal decomposition |journal=The Chinese Journal of Nonferrous Metals |date=2006 |volume=16 |issue=11 |pages=1976–1982 |url=http://ysxb.csu.edu.cn/previewFile?id=36231978&type=pdf&lang=en |archive-url= https://web.archive.org/web/20240327045836/http://ysxb.csu.edu.cn/previewFile?id=36231978&type=pdf&lang=en|archive-date= March 27, 2024|language=chinese}}</ref><ref name="aero" />

:{{chem2|2 H[AuCl4] → Au2Cl6 + 2 HCl}}

[[File:Gold(III) chloride solution.jpg|220px|right|thumb|Concentrated aqueous solution of gold(III) chloride]]

===Decomposition===

[[Anhydrous]] {{chem2|AuCl3}} begins to decompose to [[gold(I) chloride|AuCl]] (gold(I) chloride) at around {{convert|160|°C}}, however, this, in turn, undergoes [[disproportionation]] at higher temperatures to give gold metal and AuCl₃:<ref name="encyclo">{{cite journal |author1=Michael J. Coghlan |author2=Rene-Viet Nguyen |author3=Chao-Jun Li |author4=Daniel Pflästerer |author5=A. Stephen K. Hashmi |title=Gold(III) Chloride |journal=Encyclopedia of Reagents for Organic Synthesis |date=2015 |pages=1–24 |doi=10.1002/047084289X.rn00325.pub3|isbn=9780470842898 }}</ref><ref name="decomp" />

:{{chem2|AuCl3 → AuCl + Cl2}} (160&nbsp;°C)

:{{chem2|3 AuCl → AuCl3 + 2 Au}} (>210&nbsp;°C)

Due to the disproportionation of AuCl, above 210&nbsp;°C, most of the gold is in the form of elemental gold.<ref name="vapor">{{cite journal |author1=Yiqin Chen |author2=Xuezeng Tian |author3=Wei Zeng |author4=Xupeng Zhu |author5=Hailong Hu |author6=Huigao Duan |title=Vapor-phase preparation of gold nanocrystals by chloroauric acid pyrolysis |journal=Journal of Colloid and Interface Science |date=2015 |volume=439 |pages=21–27 |doi=10.1016/j.jcis.2014.10.017 |publisher=Elsevier |pmid=25463171 |bibcode=2015JCIS..439...21C |language=en}}</ref><ref name="aero">{{cite journal |author1=Robert G. Palgrave |author2=Ivan P. Parkin |title=Aerosol Assisted Chemical Vapor Deposition of Gold and Nanocomposite Thin Films from Hydrogen Tetrachloroaurate(III) |journal=Chemistry of Materials |date=2007 |volume=19 |issue=19 |pages=4639–4647 |doi=10.1021/cm0629006 |publisher=ACS Publications |language=en}}</ref>

Gold(III) chloride is more stable in a chlorine atmosphere and can sublime at around 200&nbsp;°C without any decomposition. In a chlorine atmosphere, AuCl₃ decomposes at 254&nbsp;°C yielding AuCl which in turn decomposes at 282&nbsp;°C to elemental gold.<ref name="crys" /><ref name="aucl">{{cite journal |author1=E.M.W. Janssen |author2=J.C.W. Folmer |author3=G.A. Wiegers |title=The preparation and crystal structure of gold monochloride, AuCl |journal=Journal of the Less Common Metals |date=1974 |volume=38 |issue=1 |pages=71–76 |doi=10.1016/0022-5088(74)90204-5 |language=en}}</ref> This fact that no gold chlorides can exist above 400 °C is used in the [[Miller process]].<ref name="Ullmann">{{Cite book|title=Ullmann's Encyclopedia of Industrial Chemistry|author1=Hermann Renner |author2=Günther Schlamp|year=2000|isbn=978-3-527-30673-2|chapter=Gold, Gold Alloys, and Gold Compounds|pages=106–107 |doi=10.1002/14356007.a12_499}}</ref>

===Other reactions===

{{chem2|AuCl3}} is a [[Lewis acid]] and readily forms [[Complex (chemistry)|complexes]]. For example, it reacts with [[hydrochloric acid]] to form chloroauric acid ({{chem2|H[AuCl4]}}):<ref name="greenwood" />

:{{chem2|HCl + AuCl3 → H+ + [AuCl4]−}}

[[Chloroauric acid]] is the product formed when gold dissolves in [[aqua regia]].<ref name="greenwood" />

On contact with water, {{chem2|AuCl3}} forms [[hydrates|acidic hydrates]] and the [[conjugate base]] {{chem2|[AuCl3(OH)]−}}. A {{chem2|[[iron|Fe]](2+)}} ion may reduce it, causing elemental gold to be [[Precipitation (chemistry)|precipitated]] from the solution.<ref name="wiberg_holleman"/><ref name="Cotton">Cotton, F.A.; Wilkinson, G.; Murillo, C.A.; Bochmann, M. ''Advanced Inorganic Chemistry''; John Wiley & Sons: New York, 1999; pp. 1101-1102</ref>

Other chloride sources, such as [[Potassium chloride|KCl]], also convert {{chem2|AuCl3}} into {{chem2|[AuCl4]−}}. [[Aqueous]] solutions of {{chem2|AuCl3}} react with an aqueous base such as [[sodium hydroxide]] to form a precipitate of {{chem2|Au(OH)3}}, which will dissolve in excess NaOH to form sodium aurate ({{chem2|NaAuO2}}). If gently heated, {{chem2|Au(OH)3}} decomposes to [[gold(III) oxide]], {{chem2|Au2O3}}, and then to gold metal.<ref name="greenwood">{{cite book |author1=N. N. Greenwood |author2=A. Earnshaw |title=Chemistry of the Elements |date=1997 |publisher=[[Butterworth-Heinemann]] |location=Oxford, UK |isbn=9780750633659 |pages=1184–1185 |edition=2 |language=en}}</ref><ref name="MerckIndex">''The [[Merck Index]]. An Encyclopaedia of Chemicals, Drugs and Biologicals''. 14. Ed., 2006, p. 780, {{ISBN|978-0-911910-00-1}}.</ref><ref>H. Nechamkin, ''The Chemistry of the Elements'', [[McGraw-Hill]], New York, 1968, p. 222</ref><ref>A. F. Wells, ''Structural Inorganic Chemistry'', 5th ed., [[Oxford University Press]], Oxford, UK, 1984, p. 909</ref>

Gold(III) chloride is the starting point for the [[chemical synthesis]] of many other gold compounds. For example, the reaction with [[potassium cyanide]] produces the water-soluble complex, {{chem2|K[Au(CN)4]}}:<ref>{{cite journal |author1=Henry K. Lutz |title=Synthesis and Analyses of KAu(CN)4 |journal=Honors Theses. |date=1961 |url=https://digitalworks.union.edu/theses/1986 |publisher=Union Digital Works |language=en}}</ref>

:{{chem2|AuCl3 + 4 KCN → K[Au(CN)4] + 3 KCl}}

[[Gold(III) fluoride]] can be also produced from gold(III) chloride by reacting it with [[bromine trifluoride]].<ref name="greenwood" />

Gold(III) chloride reacts with [[benzene]] under mild conditions (reaction times of a few minutes at room temperature) to produce the dimeric phenylgold(III) dichloride; a variety of other [[arenes]] undergo a similar reaction:<ref>{{Cite journal|last1=Li|first1=Zigang|last2=Brouwer|first2=Chad|last3=He|first3=Chuan|date=2008-08-01|title=Gold-Catalyzed Organic Transformations|journal=[[Chemical Reviews]]|volume=108|issue=8|pages=3239–3265|doi=10.1021/cr068434l|pmid=18613729|issn=0009-2665}}</ref>

:{{chem2|2 PhH + Au2Cl6 → [PhAuCl2]2 + 2 HCl}}

Gold(III) chloride reacts with [[carbon monoxide]] in a variety of ways. For example, the reaction of anhydrous AuCl₃ and carbon monoxide under SOCl₂ produces [[gold(I,III) chloride]] with Au(CO)Cl as an intermediate:<ref>{{cite journal |author1=Daniela Belli Dell'Amico |author2=Fausto Calderazzo |author3=Fabio Marchetti |author4=Stefano Merlino |author5=Giovanni Perego |title=X-Ray crystal and molecular structure of Au4Cl8, the product of the reduction of Au2Cl6 by Au(CO)Cl |journal=Journal of the Chemical Society, Chemical Communications |date=1977 |pages=31–32 |doi=10.1039/C39770000031 |language=en}}</ref><ref>{{cite journal |author1=Daniela Belli Dell'Amico |author2=Fausto Calderazzo |author3=Fabio Marchetti |author4=Stefano Merlino |title=Synthesis and molecular structure of [Au4Cl8], and the isolation of [Pt(CO)Cl5]– in thionyl chloride |journal=Journal of the Chemical Society, Dalton Transactions |date=1982 |issue=11 |pages=2257–2260 |doi=10.1039/DT9820002257 |language=en}}</ref>

:2 AuCl₃ + 2 CO → Au₄Cl₈ + 2 COCl₂

If carbon monoxide is in excess, Au(CO)Cl is produced instead.<ref>{{cite book |chapter=Carbonylchlorogold(I) |date=1986 |volume=24 |pages=236–238 |doi=10.1002/9780470132555.ch66 |title=Inorganic Syntheses |last1=Dell'Amico |first1=D. Belli |last2=Calderazzo |first2=F. |last3=Murray |first3=H. H. |author4-link=John P. Fackler Jr. |last4=Fackler |first4=J. P. |isbn=9780470132555 }}</ref><ref name="cocl2" />

However, under [[tetrachloroethylene]] and at 120&nbsp;°C, gold(III) chloride is first reduced to gold(I) chloride, which further reacts to form Au(CO)Cl. AuCl₃ is also known to catalyze the production of [[phosgene]].<ref name="cocl2">{{cite book |author1=T.A. Ryan |author2=E.A. Seddon |author3=K.R. Seddon |author4=C. Ryan |title=Phosgene And Related Carbonyl Halides |date=1996 |publisher=Elsevier Science |isbn=9780080538808 |pages=242–243 |language=en}}</ref><ref>{{cite journal |author1=M. S. Kharasch |author2=H. S. Isbell |title=The Chemistry of Organic Gold Compounds. I. Aurous Chloride Carbonyl and a Method of Linking Carbon to Carbon |journal=Journal of the American Chemical Society |date=1930 |volume=52 |issue=7 |pages=2919–2927 |doi=10.1021/ja01370a052 |language=en}}</ref>

==Applications==

Although gold(III) chloride has no commercial uses, it has many uses in the laboratory.<ref name="encyclo" />

===Organic synthesis===

Since 2003, {{chem2|AuCl3}} has attracted the interest of organic chemists as a mild acid catalyst for various reactions,<ref>G. Dyker, ''An Eldorado for Homogeneous Catalysis?'', in ''Organic Synthesis Highlights V'', H.-G. Schmaltz, T. Wirth (eds.), pp 48–55, [[Wiley-VCH]], Weinheim, 2003</ref> although no transformations have been commercialised. Gold(III) [[salt (chemistry)|salts]], especially [[sodium tetrachloroaurate|{{chem2|Na[AuCl4]}}]], provide an alternative to [[mercury (element)|mercury]](II) salts as catalysts for reactions involving [[alkynes]]. An illustrative reaction is the hydration of terminal alkynes to produce [[acetyl]] compounds.<ref>{{cite journal |author1=Y. Fukuda |author2=K. Utimoto | title = Effective transformation of unactivated alkynes into ketones or acetals with a gold(III) catalyst | journal = [[J. Org. Chem.]] | year = 1991 | volume = 56 | issue = 11 | doi = 10.1021/jo00011a058 | page = 3729}}</ref>

:[[File:Example of gold-catalyzed alkyne hydration reaction.svg|300px]]

Gold catalyses the [[alkylation]] of certain [[aromatic rings]] and the conversion of [[furans]] to [[phenols]]. Some alkynes undergo [[amination]] in the presence of gold(III) catalysts. For example, a mixture of [[acetonitrile]] and gold(III) chloride catalyses the alkylation of [[2-methylfuran]] by [[3-buten-2-one|methyl vinyl ketone]] at the 5-position:<ref name="tosyl"/>

:[[File:Alkylation reaction of 2-methylfuran with methyl vinyl ketone.svg|450px]]

The efficiency of this [[Organogold chemistry|organogold reaction]] is noteworthy because both the furan and the ketone are sensitive to side reactions such as polymerisation under acidic conditions. In some cases where alkynes are present, phenols sometimes form (Ts is an abbreviation for [[tosyl]]):<ref name="tosyl">{{cite journal |author1=A. S. K. Hashmi |author2=T. M. Frost |author3=J. W. Bats | title = Highly Selective Gold-Catalyzed Arene Synthesis | journal = [[J. Am. Chem. Soc.]] | year = 2000 | volume = 122 | issue = 46 | doi = 10.1021/ja005570d | pages = 11553}}</ref>

:[[File:AuCl3 phenol synthesis.svg|400px]]

This reaction involves a rearrangement that gives a new aromatic ring.<ref>{{cite journal |author1=A. Stephen |author2=K. Hashmi |author3=M. Rudolph |author4=J. P. Weyrauch |author5=M. Wölfle |author6=W. Frey |author7=J. W. Bats | title = Gold Catalysis: Proof of Arene Oxides as Intermediates in the Phenol Synthesis | journal = [[Angewandte Chemie International Edition]]| year = 2005 | volume = 44 | issue = 18 | doi = 10.1002/anie.200462672 | pages = 2798–801 | pmid = 15806608}}</ref>

Another example of an AuCl₃ catalyzed reaction is a hydroarylation, which is basically a [[Friedel-Crafts reaction]] using metal-alkyne complexes. Example, the reaction of [[mesitylene]] with [[phenylacetylene]]:<ref>{{Cite journal | doi = 10.1002/ejoc.200300260| title = Gold-Catalyzed Hydroarylation of Alkynes| journal = European Journal of Organic Chemistry| volume = 2003| issue = 18| pages = 3485–3496| year = 2003| last1 = Reetz | first1 = M. T. | last2 = Sommer | first2 = K. }}</ref>

:[[File:Hydroarylation_reetz.png|500x500px]]

Gold(III) chloride can be used for the direct oxidation of primary [[amines]] into ketones, such as the oxidation of [[cyclohexylamine]] to [[cyclohexanone]].<ref name="encyclo" />

:[[File:Example of oxidation by AuCl3.png|300px]]

This reaction is pH sensitive, requiring a mildly acidic pH to proceed, however, it does not require any additional steps.<ref name="encyclo" />

In the production of organogold(III) compounds, AuCl₃ is used as a source of gold. A main example of this is the production of monoarylgold(III) complexes, which are produced by direct [[electrophilic]] auration of arenes by gold(III) chloride.<ref>{{Cite journal|last1=Kharasch|first1=M. S.|last2=Isbell|first2=Horace S.|title=The Chemistry of Organic Gold Compounds. III. Direct Introduction of Gold into the Aromatic Nucleus (Preliminary Communication)|date=1931-08-01|journal=Journal of the American Chemical Society|volume=53|issue=8|pages=3053–3059|doi=10.1021/ja01359a030|issn=0002-7863}}</ref>

===Gold nanoparticles===

Gold(III) chloride is used in the synthesis of [[Colloidal gold|gold nanoparticles]], which are extensively studied for their unique size-dependent properties and applications in fields such as electronics, optics, and biomedicine. Gold nanoparticles can be prepared by reducing gold(III) chloride with a reducing agent such as [[sodium tetrafluoroborate]], followed by stabilization with a capping agent.<ref name="nano">{{cite journal |author1=M. Lin |author2=C. M. Sorensen |author3=K. J. Klabunde |title=Ligand-Induced Gold Nanocrystal Superlattice Formation in Colloidal Solution |journal=Chemistry of Materials |date=1999 |volume=11 |issue=2 |pages=198–202 |doi=10.1021/cm980665o |language=en}}</ref>

===Photography===

Gold(III) chloride has been used historically in the [[photography]] industry as a sensitizer in the production of photographic films and papers. However, with the advent of digital photography, its use in this field has diminished.<ref name="photo">{{cite journal |author1=Philip Ellis |title=Gold in photography |journal=Gold Bulletin |date=1975 |volume=8 |pages=7–12 |doi=10.1007/BF03215055 |s2cid=136538890 |language=en|doi-access=free }}</ref>

==Natural occurrence==

This compound does not occur naturally; however, a similar compound with the formula AuO(OH,Cl)·''n''H₂O is known as a product of natural gold oxidation.<ref>{{cite web |title=UM1995-16-O:AuClH |url=https://www.mindat.org/min-53581.html |website=mindat.org |access-date=27 April 2023}}</ref><ref>{{cite journal |author1=John L. Jambor |author2=Nikolai N. Pertsev |author3=Andrew C. Roberts |title=New Mineral Names |journal=American Mineralogist |date=1996 |volume=81 |page=768 |url=http://www.minsocam.org/msa/ammin/toc/Articles_Free/1996/Jambor_p766-770_96.pdf |language=en}}</ref>

==External links==

*{{Commons category-inline}}

{{Chlorides}}

[[Category:Gold(III) compounds]]

[[Category:Deliquescent materials]]

[[Category:Gold–halogen compounds]]