Chloroplatinates

Chloroplatinates are a family of coordination compounds in which platinum is coordinated to chloride ligands. The best-known member is the hexachloroplatinate(IV) anion, [PtCl6]2−, in which platinum is in the +4 oxidation state and is octahedrally coordinated by six chloride ligands. Salts formed with alkali metals such as Na+, K+, and Cs+ (for example Na2PtCl6, K2PtCl6, Cs2PtCl6) are typical representatives of the chloroplatinate class. The term can also refer to related solid or solution species derived from hexachloroplatinate chemistry.

Structure and properties: In [PtCl6]2−, the Pt center enjoys an octahedral geometry with high overall symmetry. Chloroplatinate salts are typically soluble in water and can undergo ligand substitution to form a wide range of Pt(II) and Pt(IV) complexes. The chlorido ligands effectively stabilize platinum in multiple oxidation states used in inorganic and coordination chemistry.

Preparation and occurrence: Hexachloroplatinate arises when platinum metal or Pt residues are dissolved in aqua regia and then treated with chloride sources to yield hexachloroplatinic acid, H2PtCl6. Neutralization or ion exchange provides the corresponding alkali metal chloroplatinate salts. H2PtCl6 serves as a common precursor in platinum chemistry for subsequent complex formation.

Applications: Chloroplatinate salts are widely used as convenient platinum sources for the synthesis of coordination and organometallic complexes, including Pt(II) and Pt(IV) derivatives. They are also employed in analytic and preparative chemistry and, in some contexts, as precursors for the electrodeposition of platinum.

Safety: Compounds of platinum and chloride should be handled with appropriate care, as with other heavy metal salts, following standard laboratory safety guidelines.