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
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.037.233
EC Number
  • 240-973-0
UNII
Properties
(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
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 pictograms
GHS Signal word Danger
H290, H301, H317, H318, H334
P234, P261, P264, P270, P272, P280, P285, P301+310, P302+352, P304+341, P305+351+338, P310, P321, P330, P333+313, P342+311, P363, P390, P404, P405, P501
Lethal dose or concentration (LD, LC):
195 mg/kg rat
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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]

References
  1. "ammonium hexachloroplatinate(IV)". Chemister.ru. 2007-03-19. Retrieved 2014-06-03.
  2. George B. Kauffman (1967). "Ammonium Hexachloroplatinate(IV)". Inorganic Syntheses. Inorganic Syntheses. 9: 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
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