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	{{chembox		{{chembox
			| Watchedfields = changed
	| verifiedrevid = 396311264		| verifiedrevid = 441677940
	| ImageFile = Dihydrogen hexachloroplatinate (IV) hexahydrate.svg
		⚫	| ImageFile = Chloroplatinic-acid-2D.svg
	<!-- | ImageSize = 200px -->
			| ImageAlt = Structural formulas of the component ions of chloroplatinic acid
	| ImageName = Dihydrogen hexachloroplatinate (IV) hexahydrate
			| ImageFile2 = (H3O)2PtCl6 structure from Xray diffraction.tif
⚫	| ImageFile1 = Chloroplatinic acid.jpg
			| ImageSize2 = 240
⚫	| IUPACName = Dihydrogen hexachloroplatinate(2–)
			| ImageAlt2 = Xray diffraction structure
	| OtherNames = Hexachloroplatinic acid
			| ImageFile3 = Chloroplatinic_acid_with_label.jpg
⚫	| Section1 = {{Chembox Identifiers
			| ImageAlt3 = Two rough red crystals in a glass tube, next to a worn leathery red and white label saying "platina chloride"
⚫	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
		⚫	| IUPACName = Dihydronium hexachloroplatinate(2–)
			| OtherNames = Hexachloroplatinic acid<br>Hydronium hexachloroplatinate(IV)
		⚫	| Section1 = {{Chembox Identifiers
		⚫	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| ChemSpiderID = 55731		| ChemSpiderID = 55731
	| PubChem = 61859		| PubChem = 61859
	| UNII_Ref = {{fdacite|correct|FDA}}		| UNII_Ref = {{fdacite|correct|FDA}}
	| UNII = Q65224GJ7F		| UNII = Q65224GJ7F
			| UNNumber = 2507
	| InChI = 1/6ClH.Pt/h6*1H;/q;;;;;;+4/p-4/rCl6Pt/c1-7(2,3,4,5)6/q-2/p+2		| InChI = 1/6ClH.Pt/h6*1H;/q;;;;;;+4/p-4/rCl6Pt/c1-7(2,3,4,5)6/q-2/p+2
	| SMILES = ..Cl(Cl)(Cl)(Cl)(Cl)Cl		| SMILES = Cl(Cl)(Cl)(Cl)(Cl)Cl..
	| InChIKey = GBFHNZZOZWQQPA-DUMOQKOKAQ		| InChIKey = GBFHNZZOZWQQPA-DUMOQKOKAQ
	| StdInChI_Ref = {{stdinchicite|correct|chemspider}}		| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
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	| StdInChIKey = GBFHNZZOZWQQPA-UHFFFAOYSA-J		| StdInChIKey = GBFHNZZOZWQQPA-UHFFFAOYSA-J
	| CASNo = 16941-12-1		| CASNo = 16941-12-1
	| CASNo_Ref = {{cascite|correct|CAS}}		| CASNo_Ref = {{cascite|correct|CAS}}
	| RTECS = TP1510000		| RTECS = TP1510000
	| EINECS = 241-010-7		| EINECS = 241-010-7
	}}		}}
	| Section2 = {{Chembox Properties		| Section2 = {{Chembox Properties
	| Formula = H<sub>2</sub>PtCl<sub>6</sub>		| Formula = H<sub>2</sub>Cl<sub>6</sub>Pt
	| MolarMass = 409.81 g/mol		| MolarMass = 409.81 g/mol
	| Appearance = Reddish brown solid		| Appearance = Reddish brown solid
	| Density = 2.431 g/cm<sup>3</sup>		| Density = 2.431 g/cm<sup>3</sup>
	| Solubility = highly soluble		| Solubility = highly soluble
	| MeltingPt = 60 °C (333 K)		| MeltingPtC = 60
			| MeltingPt_notes =
	| BoilingPt = decomp
	| pKa =		| BoilingPt = decomposes
			| pKa =
	}}		}}
	| Section3 = {{Chembox Structure		| Section3 = {{Chembox Structure
	| Coordination = octahedral		| Coordination = octahedral
	| CrystalStruct = Anti-fluorite.		| CrystalStruct = Anti-fluorite.
	| Dipole = 0 ]		| Dipole = 0 ]
	}}		}}
	| Section7 = {{Chembox Hazards		| Section7 = {{Chembox Hazards
			| ExternalSDS =
	| ExternalMSDS =
	| EUIndex = 078-009-00-4		| NFPA-H = 4
		⚫	| NFPA-F = 0
	| EUClass = Toxic ('''T''')<br/>Corrosive ('''C''')
	| NFPA-H = 2		| NFPA-R = 2
	| NFPA-F = 0		| NFPA-S = W
			| GHSPictograms = {{GHS05}}{{GHS06}}{{GHS07}}{{GHS08}}
⚫	| NFPA-R = 1
	| NFPA-O =		| GHSSignalWord = Danger
	| RPhrases = {{R25}}, {{R34}}, {{R42/43}}		| HPhrases = {{H-phrases|301|314|317|334}}
			| PPhrases = {{P-phrases|260|261|264|270|272|280|285|301+310|301+330+331|302+352|303+361+353|304+340|304+341|305+351+338|310|321|330|333+313|342+311|363|405|501}}
	| SPhrases = {{S1/2}}, {{S22}}, {{S26}}, {{S36/37/39}}, {{S45}}
⚫	}}
⚫	| Section8 = {{Chembox Related
⚫	| OtherAnions = Hexachloropalladic acid
⚫	| OtherCations = ],<br /> ],<br /> Rubidium hexachloroplatinate,<br /> Caesium hexachloroplatinate
	| Function = ]
	| OtherFunctn =
	}}		}}
		⚫	| Section8 = {{Chembox Related
		⚫	| OtherAnions = Hexachloropalladic acid
		⚫	| OtherCations = ],<br /> ],<br /> Rubidium hexachloroplatinate,<br /> Caesium hexachloroplatinate
			| OtherFunction_label =
			| OtherFunction =
		⚫	}}
	}}		}}
	'''Chloroplatinic acid''' or '''hexachloroplatinic acid''' is the ] usually found as the hexahydrate with the formula H<sub>2</sub>PtCl<sub>6</sub>·(H<sub>2</sub>O)<sub>6</sub>. This is one of the most readily available soluble compounds of ]. It is rarely obtained in the pure state. The commercial product is the ] salt of the hexachloroplatinate(IV) anion. Therefore, the correct formula is <sub>2</sub>·4H<sub>2</sub>O.<ref name=SchweizerThermalDecomp/><ref>{{cite book | author = Holleman, Wiberg | title = Inorganic Chemistry | edition = First | publisher = Academic Press | location = New York | year = 2001 | isbn = 0123526515}}</ref> The related palladium compound, <sub>2</sub> is extremely unstable and has not been isolated in pure form.<ref>{{cite book | author = Greenwood, N.N.; Earnshaw, A. | title = Chemistry of the Elements | edition = Second | publisher = Elsevier Butterworth-Heinemann | location = New York | year = 1997 | isbn = 978-0750633659}}</ref>		'''Chloroplatinic acid''' (also known as '''hexachloroplatinic acid''') is an ] with the formula <sub>2</sub>(H<sub>2</sub>O)<sub>''x''</sub> (0 ≤ ''x'' ≤ 6). A red solid, it is an important commercial source of ], usually as an aqueous solution. Although often written in shorthand as H<sub>2</sub>PtCl<sub>6</sub>, it is the ] (H<sub>3</sub>O<sup>+</sup>) salt of the hexachloroplatinate anion ({{chem|PtCl|6|2-}}).<ref name=SchweizerThermaldecomposes/><ref>{{cite book | author = Holleman |author2=Wiberg | title = Inorganic Chemistry | edition = First | publisher = Academic Press | location = New York | year = 2001 | isbn = 0-12-352651-5}}</ref><ref>{{cite book | last1= Greenwood |first1=N. N. |last2=Earnshaw |first2=A. | title = Chemistry of the Elements | edition = Second | publisher = Elsevier Butterworth-Heinemann | location = New York | year = 1997 | isbn = 978-0-7506-3365-9}}</ref> Hexachloroplatinic acid is highly ].
	==Production==		==Production==
	]		]
			Hexachloroplatinic acid may be produced via a variety of methods. The most common of these methods involves dissolution of platinum in ]. Other methods include exposing an aqueous suspension of platinum particles to chlorine gas, or via electrolysis.
	Chloroplatinic acid is produced by dissolving platinum ] in ]. This reaction is rumored to produce nitrogen-containing platinum compounds, but the product is H<sub>2</sub>PtCl<sub>6</sub>. Chloroplatinic acid is brownish-red, and can be isolated by evaporating this solution to a syrup.<ref>{{cite journal | title = Ammonium Hexachloroplatinate(IV) | author = ] | year = 1967 | journal = ] | volume = 9 | pages = 182–185 | doi = 10.1002/9780470132401.ch51 | last2 = Thurner | first2 = Joseph J. | last3 = Zatko | first3 = David A.}}</ref>
			When produced by the aqua regia route, hexachloroplatinic acid is thought to arise by the following equation: <ref name="IS">{{cite book | chapter = Ammonium Hexachloroplatinate(IV) | first= George B. |last=Kauffman | title= Inorganic Syntheses | year = 1967 | series = ] | volume = 9 | pages = 182–185 | doi = 10.1002/9780470132401.ch51| isbn= 9780470132401 }}</ref><ref name=Brauer>{{cite book|first=H. |last=Grube |chapter=Hexachloroplatinic(IV) Acid |title=Handbook of Preparative Inorganic Chemistry |edition=2nd |editor-first=G. |editor-last=Brauer |publisher=Academic Press |date=1963 |location=New York |volume=2 |page=1569}}</ref>
⚫	: Pt + 4 HNO<sub>3</sub> + 6 HCl → H<sub>2</sub>PtCl<sub>6</sub> + 4 NO<sub>2</sub> + 4 H<sub>2</sub>O
		⚫	{{block indent|Pt + 4&nbsp;HNO<sub>3</sub> + 6&nbsp;HCl → H<sub>2</sub>PtCl<sub>6</sub> + 4&nbsp;NO<sub>2</sub> + 4&nbsp;H<sub>2</sub>O}}
⚫	Alternative methods have been heavily investigated, but the older literature can be unreliable.<ref>{{cite journal | title = The Preparation of Hydrochloroplatinic Acid by means of Hydrogen Peroxide | year = 1917 | author = Paul Rudnick and R. D. Cooke | journal = ] | volume = 39 | issue = 4 | pages = 633–635 | doi = 10.1021/ja02249a011}}</ref>
			The resulting orange/red solution can be evaporated to produce brownish red crystals. Some authors suggest that hexachloroplatinic acid produced using this method is contaminated with nitrosonium hexachloroplatinate. Newer literature indicates that this is not the case, and that once the nitric acid has been driven off, samples prepared via this method contain no detectable nitrogen.
⚫	==Reactions==
⚫	When hexachloroplatinic acid is heated, it decomposes through ], ], to elemental platinum, although the reactions do not occur stepwise, cleanly:<ref name=SchweizerThermalDecomp>{{cite journal | author = A. E. Schweizer, G. T. Kerr | title = Thermal Decomposition of Hexachloroplatinic Acid | journal = ] | year = 1978 | volume = 17 | issue = 8 | pages = 2326–2327 | doi = 10.1021/ic50186a067}}</ref>
		⚫	Alternative methods have been investigated and described, often motivated by the avoidance of nitrogen contamination.<ref>{{cite journal | title = The Preparation of Hydrochloroplatinic Acid by Means of Hydrogen Peroxide | year = 1917 | first1= Paul |last1=Rudnick |first2=R. D. |last2=Cooke | journal = ] | volume = 39 | issue = 4 | pages = 633–635 | doi = 10.1021/ja02249a011| url = https://zenodo.org/record/1429058 }}</ref>
⚫	: (H<sub>3</sub>O)<sub>2</sub>PtCl<sub>6</sub>&middot;''n'' H<sub>2</sub>O {{eqm}} PtCl<sub>4</sub> + 2 HCl + (''n'' + 2) H<sub>2</sub>O
	: PtCl<sub>4</sub> {{eqm}} PtCl<sub>2</sub> + Cl<sub>2</sub>
	: PtCl<sub>2</sub> {{eqm}} Pt + Cl<sub>2</sub>
		⚫	==Reactions==
	All three reactions are reversible.
		⚫	When heated, hexachloroplatinic acid decomposes to ].<ref name=SchweizerThermaldecomposes>{{cite journal | first1= A. E. |last1=Schweizer |first2=G. T. |last2=Kerr | title = Thermal Decomposition of Hexachloroplatinic Acid | journal = ] | year = 1978 | volume = 17 | issue = 8 | pages = 2326–2327 | doi = 10.1021/ic50186a067}}</ref>
		⚫	{{block indent|(H<sub>3</sub>O)<sub>2</sub>PtCl<sub>6</sub>·''n''H<sub>2</sub>O → PtCl<sub>4</sub> + 2&nbsp;HCl + (''n''&nbsp;+&nbsp;2)&nbsp;H<sub>2</sub>O}}
	==Applications==		==Applications==
	===Potassium determination===		===Potassium determination===
	{{see also|Potassium hexachloroplatinate}}		{{see also|Potassium hexachloroplatinate}}
	Chloroplatinic acid was popularized for the determination of potassium. The potassium is selectively precipitated as potassium chloroplatinate. Determinations were done in 85% (v/v) alcohol solutions with excess platinate ions, and the precipitated product was weighed. Potassium could be detected for solutions as dilute as 0.02 to 0.2% (m/v).<ref>{{cite journal | author = G. F. Smith, J. L. Gring | title = The Separation and Determination of the Alkali Metals Using Perchloric Acid. V. Perchloric Acid and Chloroplatinic Acid in the Determination of Small Amounts of Potassium in the Presence of Large Amounts of Sodium | journal = ] | year = 1933 | volume = 55 | issue = 10 | pages = 3957–3961 | doi = 10.1021/ja01337a007}}</ref>		Chloroplatinic acid was popularized for the ] of potassium. The potassium is selectively precipitated from ] as potassium hexachloroplatinate. Determinations were done in 85% (v/v) alcohol solutions with excess platinate ions, and the precipitated product was weighed. Potassium could be detected for solutions as dilute as 0.02 to 0.2% (m/v).<ref name="Smith 1933">{{cite journal | first1= G. Frederick |last1=Smith |first2=J. L.|last2= Gring | title = The Separation and Determination of the Alkali Metals Using Perchloric Acid. V. Perchloric Acid and Chloroplatinic Acid in the Determination of Small Amounts of Potassium in the Presence of Large Amounts of Sodium | journal = ] | year = 1933 | volume = 55 | issue = 10 | pages = 3957–3961 | doi = 10.1021/ja01337a007}}</ref>
	This method for determination of potassium was advantageous vs. the cobaltinitrite method used previously, since it required a single ] reaction.{{Fact|date=October 2007}} Today, the concentration of potassium is determined with an ]. These modern methods remain subject to interference.		This method for determination of potassium was advantageous compared to the ] method used previously, since it required a single ] reaction.<ref name="Smith 1933"/> ] analysis of precipitated products has been supplanted by modern ] methods such as ]s, ], ] or ].
	===Purification of platinum===		===Purification of platinum===
	{{see also|Ammonium hexachloroplatinate}}		{{see also|Ammonium hexachloroplatinate}}
	Treatment with an ammonium salt, such as ], gives ],<ref name=Kauuf>{{cite journal | title = Ammonium Hexachloroplatinate(IV) | author = ] | year = 1967 | journal = ] | volume = 9 | pages = 182–185 | doi = 10.1002/9780470132401.ch51 | last2 = Thurner | first2 = Joseph J. | last3 = Zatko | first3 = David A.}}</ref> which is very insoluble in ammonium solutions. Heating the ammonium salt in hydrogen reduces it to elemental platinum. Platinum is often isolated from ores or recycled from residues thus.<ref>Cotton, S. A. Chemistry of Precious Metals, Chapman and Hall (London): 1997. ISBN 0-7514-0413-6.</ref>		Upon treatment with an ammonium salt, such as ], chloroplatinic acid converts to ], which precipitates as a solid.<ref name=IS/> Upon heating in an atmosphere of ], the ammonium salt converts to elemental platinum. Platinum is often isolated from ores or recycled from residues using this method.<ref>{{cite book|last=Cotton |first=S. A. |title=Chemistry of Precious Metals |publisher=Chapman and Hall |location=London |date=1997 |isbn=0-7514-0413-6}}</ref>
	===Catalysis===		===Catalysis===
	Like many platinum compounds, chloroplatinic acid is used in catalysis. This compound was first reported by John Speier and colleagues from ] to catalyze the reaction of silyl hydrides with olefins, hydrosilylation.(3) Typical of his reactions, Speier used isopropanol solutions containing trichlorosilane (SiHCl<sub>3</sub>), and methyldichlorosilane (CH<sub>3</sub>HSiCl<sub>2</sub>), with pentenes. Prior work on the addition of silanes to alkenes required radical reactions that were inefficient.<ref>{{cite journal | author = J. L. Speier, J. A. Webster, G. H. Barnes | title = The Addition of Silicon Hydrides to Olefinic Double Bonds. Part II. The Use of Group VIII Metal Catalysts | journal = ] | year = 1957 | volume = 79 | issue = 4 | pages = 974–979 | doi = 10.1021/ja01561a054}}</ref><ref>{{cite journal | author = John C. Saam, John L. Speier | title = The Addition of Silicon Hydrides to Olefinic Double Bonds. Part III. The Addition to Non-terminal Olefins in the Presence of Chloroplatinic Acid | journal = ] | year = 1958 | volume = 80 | issue = 15 | pages = 4104–4106 | doi = 10.1021/ja01548a073}}</ref> It is generally agreed that chloroplatinic acid is a catalyst precursor, and more recent discussions have considered a possible role for colloidal platinum or zero-valent complexes.<ref>{{cite journal | author = L. N. Lewis, K. G. Sy, G. L. Bryant and P. E. Donahue | title = Platinum-catalyzed hydrosilylation of alkynes | year = 1991 | journal = ] | volume = 10 | issue = 10 | pages = 3750–3759 | doi = 10.1021/om00056a055}}</ref>		Like many platinum compounds, chloroplatinic acid is a catalyst (or precatalyst) for ] and related reactions. As first reported by John Speier and colleagues from ], it catalyzes the addition of hydrosilanes to olefins, i.e. ]. Early demonstration reactions used isopropanol solutions of ] (SiHCl<sub>3</sub>) with ]s. Prior work on the addition of silanes to alkenes required radical reactions that were inefficient.<ref>{{cite journal | first1= J. L.|last1= Speier |first2=J. A. |last2=Webster |first3=G. H. |last3=Barnes | title = The Addition of Silicon Hydrides to Olefinic Double Bonds. Part II. The Use of Group VIII Metal Catalysts | journal = ] | year = 1957 | volume = 79 | issue = 4 | pages = 974–979 | doi = 10.1021/ja01561a054}}</ref><ref>{{cite journal |first1=John C. |last1=Saam |first2=John L. |last2=Speier | title = The Addition of Silicon Hydrides to Olefinic Double Bonds. Part III. The Addition to Non-terminal Olefins in the Presence of Chloroplatinic Acid | journal = ] | year = 1958 | volume = 80 | issue = 15 | pages = 4104–4106 | doi = 10.1021/ja01548a073}}</ref> As well as with ], Speier's catalyst enjoys widespread use for hydrosilylation, the main drawback is the deliquescent properties of the catalyst.<ref>{{cite encyclopedia |first= Mukund P. |last= Sibi |chapter= Hydrogen Hexachloroplatinate(IV) |encyclopedia= Encyclopedia of Reagents for Organic Synthesis |year= 2001 |publisher= John Wiley & Sons |doi= 10.1002/047084289X.rh038|isbn= 0471936235 }}</ref>
			It is generally agreed that chloroplatinic acid is a precursor to the actual catalyst. A possible role for colloidal platinum or ] complexes has also been considered.<ref>{{cite journal | first1= L. N. |last1=Lewis |first2=K. G. |last2=Sy |first3=G. L. |last3=Bryant |first4= P. E. |last4=Donahue | title = Platinum-catalyzed hydrosilylation of alkynes | year = 1991 | journal = ] | volume = 10 | issue = 10 | pages = 3750–3759 | doi = 10.1021/om00056a055}}</ref>
	==Related compounds==		==Related compounds==
	Chloroplatinic acid prepared from ] is occasionally contaminated with (NO)<sub>2</sub>PtCl<sub>6</sub>. This species is obtained by the reaction of ] and Pt metal.<ref>{{cite journal | author = R. T. Moravek, G. B. Kauffman and T. Mahmood | title = Nitrosyl Hexachloroplatinate(IV) | year = 1967 | journal = ] | volume = 9 | issue = | pages = 217–220 | doi = 10.1002/9780470132555.ch63}}</ref>		Chloroplatinic acid prepared from ] is proposed to contain nitrosonium hexachloroplatinate, (NO)<sub>2</sub>PtCl<sub>6</sub>. Nitrosonium hexachloroplatinate is obtained by the reaction of ] (NOCl) and platinum metal.<ref>{{cite book | first1= R. T.|last1= Moravek |first2=G. B. |last2=Kauffman |first3=T. |last3=Mahmood | title = Nitrosyl Hexachloroplatinate(IV) | year = 1967 | series = ] | volume = 9 | pages = 217–220 | doi = 10.1002/9780470132555.ch63|isbn= 9780470132555 }}</ref> Nitrosonium hexachloroplatinate has been found to react vigorously with water and hydrochloric acid, making contamination of chloroplatinic acid prepared with aqua regia with nitrosonium hexachloroplatinate unlikely.{{cn|date=September 2023}}
	==References==		==References==
	{{reflist}}		{{reflist}}
		⚫	{{Platinum compounds}}
	{{Hydrogen compounds}}		{{Hydrogen compounds}}
	]		]
	]		]
⚫	]
	]
	]
	]
	]
	]
	]
	]
	]
	]
	]