Platinum(IV) chloride
Encyclopedia
Platinum chloride is the inorganic compound
of platinum
and chlorine
with the empirical formula PtCl4. This brown solid features platinum in the 4+ oxidation state.
, {PtCl6}. This geometry is achieved by forming a polymer wherein half of the chloride ligands bridge between the platinum centers. Because of its polymeric structure, PtCl4 dissolves only upon breaking the chloride bridging ligand
s. Thus, addition of HCl give H2PtCl6. Lewis base adduct
s of Pt(IV) of the type cis-PtCl4L2 are known, but most are prepared by oxidation of the Pt(II) derivatives.
. Heating H2PtCl6 gives PtCl4:
If excess acids are removed, PtCl4 crystallizes from aqueous solutions in large red crystals of pentahydrate PtCl4·5(H2O), which can be dehydrated by heating to about 300 °C in a current of dry chlorine. The pentahydrate is stable and is used as the commercial form of PtCl4.
Treatment of PtCl4 with aqueous base gives the [Pt(OH)6]2− ion. With methyl Grignard reagents followed by partial hydrolysis, PtCl4 converts to the cuboidal cluster [Pt(CH3)3(OH)]4. Upon heating PtCl4 evolves chlorine
to give PtCl2
:
The heavier halides, PtBr4 and PtI4, are also known.
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
of platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
and chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
with the empirical formula PtCl4. This brown solid features platinum in the 4+ oxidation state.
Structure
Typical of Pt(IV), the metal centers adopt an octahedral coordination geometryOctahedral molecular geometry
In chemistry, octahedral molecular geometry describes the shape of compounds where in six atoms or groups of atoms or ligands are symmetrically arranged around a central atom, defining the vertices of an octahedron...
, {PtCl6}. This geometry is achieved by forming a polymer wherein half of the chloride ligands bridge between the platinum centers. Because of its polymeric structure, PtCl4 dissolves only upon breaking the chloride bridging ligand
Bridging ligand
A bridging ligand is a ligand that connects two or more atoms, usually metal ions. The ligand may be atomic or polyatomic. Virtually all complex organic compounds can serve as bridging ligands, so the term is usually restricted to small ligands such as pseudohalides or to ligands that are...
s. Thus, addition of HCl give H2PtCl6. Lewis base adduct
Adduct
An adduct is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components. The resultant is considered a distinct molecular species...
s of Pt(IV) of the type cis-PtCl4L2 are known, but most are prepared by oxidation of the Pt(II) derivatives.
| |
Crystal structure In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry... of platinum(IV) chloride |
Formation and reactions
PtCl4 is mainly encountered in the handling of chloroplatinic acid, obtained by dissolving of Pt metal in aqua regiaAqua regia
Aqua regia or aqua regis is a highly corrosive mixture of acids, fuming yellow or red solution, also called nitro-hydrochloric acid. The mixture is formed by freshly mixing concentrated nitric acid and hydrochloric acid, usually in a volume ratio of 1:3, respectively...
. Heating H2PtCl6 gives PtCl4:
- H2PtCl6 → PtCl4 + 2 HCl
If excess acids are removed, PtCl4 crystallizes from aqueous solutions in large red crystals of pentahydrate PtCl4·5(H2O), which can be dehydrated by heating to about 300 °C in a current of dry chlorine. The pentahydrate is stable and is used as the commercial form of PtCl4.
Treatment of PtCl4 with aqueous base gives the [Pt(OH)6]2− ion. With methyl Grignard reagents followed by partial hydrolysis, PtCl4 converts to the cuboidal cluster [Pt(CH3)3(OH)]4. Upon heating PtCl4 evolves chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
to give PtCl2
Platinum(II) chloride
Platinum chloride is the chemical compound PtCl2. It is an important precursor used in the preparation of other platinum compounds. It exists in two crystalline forms, but the main properties are somewhat similar: dark brown, insoluble in water, diamagnetic, and odorless.-Structure:The...
:
- PtCl4 → PtCl2 + Cl2
The heavier halides, PtBr4 and PtI4, are also known.