Ammonium hexachloroplatinate

Overview
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.

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. 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.

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.