Hexachloroplatinate

Hexachloroplatinate refers to the hexachloroplatinate(IV) anion, [PtCl6]2-, and the family of salts and acids that contain it. The anion consists of a platinum center in the +4 oxidation state coordinated octahedrally by six chloride ligands. Common salts include potassium hexachloroplatinate (K2PtCl6) and ammonium hexachloroplatinate ((NH4)2PtCl6); chloroplatinic acid is often described as H2PtCl6 (H2[PtCl6]).

Structurally, [PtCl6]2- is a low-spin d6 complex and is diamagnetic. Many hexachloroplatinate salts are crystalline and vary in water solubility depending on the counterion; ammonium hexachloroplatinate is notably sparingly soluble and has been used historically for platinum separation and purification by precipitation. The anion is stable in strongly acidic chloride media but can be reduced to platinum(0) under reducing conditions or hydrolyzed under strongly basic conditions.

Applications include use as a precursor to platinum metal and complexes, reagents in inorganic synthesis, catalyst precursors for hydrogenation and oxidation reactions, and in analytical chemistry for gravimetric or qualitative determination of platinum. Handling requires care: platinum compounds may be allergenic or toxic, and chlorinated metal salts should be managed with appropriate laboratory safety measures. Hexachloroplatinate belongs to the broader class of halometallates and is of interest in coordination chemistry and materials processing.