ammonium hexachloroplatinate
{{chembox
| Watchedfields = changed
| verifiedrevid = 443387206
| Name = Ammonium hexachloroplatinate
| ImageFile = (NH4)2PtCl6.svg
| ImageSize = 200px
| ImageName = Ammonium hexachloroplatinate
| ImageFile2 = (NH4)2PtCl6Xray.tif
| ImageSize2 = 320px
| ImageName2 = Ammonium hexachloroplatinate
| IUPACName = Ammonium hexachloroplatinate(IV)
| OtherNames = ammonium chloroplatinate
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 10628022
| PubChem = 16211460
| EINECS = 240-973-0
| InChI = 1/6ClH.2H3N.Pt/h6*1H;2*1H3;/q;;;;;;;;+4/p-4/rCl6Pt.2H3N/c1-7(2,3,4,5)6;;/h;2*1H3/q-2;;/p+2
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 59604
| SMILES = [NH4+].[NH4+].Cl[Pt-2](Cl)(Cl)(Cl)(Cl)Cl
| InChIKey = PCCGQTHFYHJATL-WPAIPAOFAY
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/6ClH.2H3N.Pt/h6*1H;2*1H3;/q;;;;;;;;+4/p-4
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = PCCGQTHFYHJATL-UHFFFAOYSA-J
| CASNo_Ref = {{cascite|correct|??}}
| CASNo = 16919-58-7
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 1653N9XMIC
}}
|Section2={{Chembox Properties
| Formula = (NH4)2PtCl6
| MolarMass = 443.87 g/mol
| Odor = odorless
| Appearance = yellow crystals
| Density = 3.065 g/cm3
| MeltingPtC = 380
| MeltingPt_notes = decomposes
| Solubility = 0.289 g/100ml (0 °C)
0.7 g/100ml (15 °C){{cite web|url=http://chemister.ru/Database/properties-en.php?dbid=1&id=7145 |title=ammonium hexachloroplatinate(IV) |publisher=Chemister.ru |date=2007-03-19 |accessdate=2014-06-03}}
0.499 g/100ml (20 °C)
3.36 g/100ml (100 °C)}}
| Section7 = {{Chembox Hazards
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| GHSPictograms = {{GHS05}}{{GHS06}}{{GHS08}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|290|301|317|318|334}}
| PPhrases = {{P-phrases|234|261|264|270|272|280|285|301+310|302+352|304+341|305+351+338|310|321|330|333+313|342+311|363|390|404|405|501}}
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| LD50 = 195 mg/kg rat
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Ammonium hexachloroplatinate, also known as ammonium chloroplatinate, is the inorganic compound with the formula (NH4)2[PtCl6]. It is a rare example of a soluble platinum(IV) salt that is not hygroscopic. It forms intensely yellow solutions in water. In the presence of 1M NH4Cl, its solubility is only 0.0028 g/100 mL.
Preparation and structure
The compound consists of separate tetrahedral ammonium cations and octahedral [PtCl6]2− anions. It is usually generated as a fine yellow precipitate by treating a solution of hexachloroplatinic acid with a solution of an ammonium salt.{{cite book | chapter = Ammonium Hexachloroplatinate(IV) | author = George B. Kauffman | title = Inorganic Syntheses | author-link = George B. Kauffman | year = 1967 | volume = 9 | pages = 182–185 | doi = 10.1002/9780470132401.ch51 | isbn = 978-0-470-13240-1}} The complex is so poorly soluble that this step is employed in the isolation of platinum from ores and recycled residues.Cotton, S. A. Chemistry of Precious Metals, Chapman and Hall (London): 1997. {{ISBN|0-7514-0413-6}}.
As analyzed by X-ray crystallography, the salt crystallizes in a cubic motif reminiscent of the fluorite structure. The [PtCl6]2− centers are octahedral. The NH4+ centers are hydrogen bonded to the chloride ligands.Verde-Gómez, Y.; Alonso-Nuñez, G.; Cervantes, F.; Keer, A. "Aqueous solution reaction to synthesize ammonium hexachloroplatinate and its crystallographic and thermogravimetric characterization" Materials Letters, 2003, volume 57, p 4667-4672. {{doi|10.1016/S0167-577X(03)00381-1}}
Uses and reactions
Ammonium hexachloroplatinate is used in platinum plating. Heating (NH4)2[PtCl6] under a stream of hydrogen at 200 °C produces platinum sponge. Treating this with chlorine gives H2[PtCl6].
Ammonium hexachloroplatinate decomposes to yield platinum sponge when heated to high temperatures:{{cite book|title=Modern Descriptive Chemistry|last1=Rochow|first1=Eugene George|year=1977|publisher=W. B. Saunders Company|page=202|isbn=9780721676289|url=https://archive.org/details/moderndescriptiv0000roch/mode/1up}}
:3(NH4)2PtCl6 → 3Pt(s) + 2NH4Cl(g) + 16HCl(g) + 2N2(g)
Safety
Dust containing ammonium hexachloroplatinate can be highly allergenic. "Symptoms range from irritation of skin and mucous membranes to life-threatening attacks of asthma."{{cite book |doi=10.1002/14356007.a21_075|chapter=Platinum Group Metals and Compounds |title=Ullmann's Encyclopedia of Industrial Chemistry |year=2001 |last1=Renner |first1=Hermann |last2=Schlamp |first2=Günther |last3=Kleinwächter |first3=Ingo |last4=Drost |first4=Ernst |last5=Lüschow |first5=Hans Martin |last6=Tews |first6=Peter |last7=Panster |first7=Peter |last8=Diehl |first8=Manfred |last9=Lang |first9=Jutta |last10=Kreuzer |first10=Thomas |last11=Knödler |first11=Alfons |last12=Starz |first12=Karl Anton |last13=Dermann |first13=Klaus |last14=Rothaut |first14=Josef |last15=Drieselmann |first15=Ralf |last16=Peter |first16=Catrin |last17=Schiele |first17=Rainer |isbn=3527306730 }}