Ammonium hexachloroplatinate

Ammonium hexachloroplatinate, also known as ammonium chloroplatinate, is an inorganic compound with the formula (NH₄)₂PtCl₆. 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 0.0028g/100 mL.

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Preparation and structure

The compound consists of separate ammonium cations and octahedral [PtCl₆]^2- anions. It is usually generated by treating a solution of chloroplatinic acid with a solution of an ammonium salt.^[1] The fine yellow salt precipitates. The complex is so poorly soluble that this step is employed in the isolation of platinum from ores and recycled residues.^[2]

Uses and reactions

This yellow powder is used in platinum plating.

Heating (NH₄)₂PtCl₆ under a stream of hydrogen at 200 °C produces platinum sponge. Treatment with chlorine gives H₂PtCl₆.^[1]

References

1. ^ ^{a b} Kauffman, G. B. "Ammonium Hexachloroplatinate" Inorganic Syntheses McGraw-Hill: New York, 1967, IX, pages 182-4.
2. ^ Cotton, S. A. Chemistry of Precious Metals, Chapman and Hall (London): 1997. ISBN 0-7514-0413-6.