Ammonium hexachloroplatinate

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.

Ammonium hexachloroplatinate

Names
IUPAC name Ammonium hexachloroplatinate(IV)
Other names ammonium chloroplatinate
Identifiers
CAS Number	16919-58-7 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:59604 Y
ChemSpider	10628022 Y
ECHA InfoCard	100.037.233
EC Number	240-973-0
PubChem CID	16211460
UNII	1653N9XMIC Y
CompTox Dashboard (EPA)	DTXSID10893445
InChI InChI=1S/6ClH.2H3N.Pt/h6*1H;2*1H3;/q;;;;;;;;+4/p-4 Y Key: PCCGQTHFYHJATL-UHFFFAOYSA-J Y 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 Key: PCCGQTHFYHJATL-WPAIPAOFAY
SMILES [NH4+].[NH4+].Cl[Pt-2](Cl)(Cl)(Cl)(Cl)Cl
Properties
Chemical formula	(NH4)2PtCl6
Molar mass	443.87 g/mol
Appearance	yellow crystals
Odor	odorless
Density	3.065 g/cm3
Melting point	380 °C (716 °F; 653 K) decomposes
Solubility in water	0.289 g/100ml (0 °C) 0.7 g/100ml (15 °C)[1] 0.499 g/100ml (20 °C) 3.36 g/100ml (100 °C)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H290, H301, H317, H318, H334
Precautionary statements	P234, P261, P264, P270, P272, P280, P285, P301+P310, P302+P352, P304+P341, P305+P351+P338, P310, P321, P330, P333+P313, P342+P311, P363, P390, P404, P405, P501
Lethal dose or concentration (LD, LC):
LD50 (median dose)	195 mg/kg rat
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

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.^[2] The complex is so poorly soluble that this step is employed in the isolation of platinum from ores and recycled residues.^[3]

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.^[4]

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].^[2]

Ammonium hexachloroplatinate decomposes to yield platinum sponge when heated to high temperatures:^[2][5]

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."^[6]

Related compounds

• Potassium hexachloroplatinate

References

1. "ammonium hexachloroplatinate(IV)". Chemister.ru. 2007-03-19. Retrieved 2014-06-03.
2. George B. Kauffman (1967). "Ammonium Hexachloroplatinate(IV)". Inorganic Syntheses. Vol. 9. pp. 182–185. doi:10.1002/9780470132401.ch51. ISBN 978-0-470-13240-1.
3. Cotton, S. A. Chemistry of Precious Metals, Chapman and Hall (London): 1997. ISBN 0-7514-0413-6.
4. 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
5. Rochow, Eugene George (1977). Modern Descriptive Chemistry. W. B. Saunders Company. p. 202. ISBN 9780721676289.
6. Renner, Hermann; Schlamp, Günther; Kleinwächter, Ingo; Drost, Ernst; Lüschow, Hans Martin; Tews, Peter; Panster, Peter; Diehl, Manfred; Lang, Jutta; Kreuzer, Thomas; Knödler, Alfons; Starz, Karl Anton; Dermann, Klaus; Rothaut, Josef; Drieselmann, Ralf; Peter, Catrin; Schiele, Rainer (2001). "Platinum Group Metals and Compounds". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a21_075. ISBN 3527306730.