chloroplatinate

Chloroplatinate is a term used for coordination compounds that contain the hexachloroplatinate(IV) anion, [PtCl6]2-. The most common members are hexachloroplatinate salts such as potassium hexachloroplatinate (K2PtCl6) and chloroplatinic acid (H2PtCl6). The [PtCl6]2- ion has a platinum(IV) center coordinated by six chloride ligands in an octahedral arrangement.

Preparation and structure: The hexachloroplatinate ion is formed in chloride-rich media by oxidation of platinum in the presence of chloride, yielding H2PtCl6, which can be isolated as various salts (for example, K2PtCl6 and Na2PtCl6). In aqueous solution the ion exists as [PtCl6]2-, and the chloride ligands can be partly displaced by other ligands to give a family of Pt chloride complexes and related Pt coordination compounds.

Reactivity: In concentrated chloride solutions, [PtCl6]2- is relatively stable and supports ligand exchange under suitable conditions. Substitution reactions can replace chloride ligands with other donors, generating species such as PtCl5L− and PtCl4L2. Reduction of hexachloroplatinate salts yields metallic platinum, often observed as finely divided Pt or black deposits.

Applications: Chloroplatinate salts serve as convenient sources of platinum for synthesis and catalysis. They are used in electroplating baths to deposit platinum coatings and as starting materials for preparing a range of Pt complexes in inorganic chemistry. In teaching and qualitative analysis, salts such as K2PtCl6 are standard Pt reagents due to their well-characterized chemistry.