Ammonium hexachloroplatinate


Ammonium hexachloroplatinate, also known as ammonium chloroplatinate, is the inorganic compound with the formula 2. It is a rare example of a soluble platinum 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 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. The complex is so poorly soluble that this step is employed in the isolation of platinum from ores and recycled residues.
As analyzed by X-ray crystallography, the salt crystallizes in a cubic motif reminiscent of the fluorite structure. The 2− centers are octahedral. The NH4+ centers are hydrogen bonded to the chloride ligands.

Uses and reactions

Ammonium hexachloroplatinate is used in platinum plating. Heating 2 under a stream of hydrogen at 200 °C produces platinum sponge. Treating this with chlorine gives H2.