Platinum(IV) chloride is the
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
of
platinum
Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish , a diminutive of "silver".
Platinu ...
and
chlorine
Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
with the empirical formula PtCl
4. This brown solid features platinum in the 4+ oxidation state.
Structure
Typical of Pt(IV), the metal centers adopt an
octahedral coordination geometry
In chemistry, octahedral molecular geometry, also called square bipyramidal, describes the shape of compounds with six atoms or groups of atoms or ligands symmetrically arranged around a central atom, defining the vertices of an octahedron. The oc ...
, . This geometry is achieved by forming a polymer wherein half of the chloride ligands bridge between the platinum centers. Because of its polymeric structure, PtCl
4 dissolves only upon breaking the chloride
bridging ligand
In coordination chemistry, 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 r ...
s. Thus, addition of HCl give H
2PtCl
6.
Lewis base
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...
adduct
An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all co ...
s of Pt(IV) of the type cis-PtCl
4L
2 are known, but most are prepared by oxidation of the Pt(II) derivatives.
Formation and reactions
PtCl
4 is mainly encountered in the handling of
chloroplatinic acid
Chloroplatinic acid (also known as hexachloroplatinic acid) is an inorganic compound with the formula 3Osub>2 tCl6H2O)''x'' (0 ≤ ''x'' ≤ 6). A red solid, it is an important commercial source of platinum, usually as an aqueous solution. Alth ...
, obtained by dissolving of Pt metal in
aqua regia. Heating H
2PtCl
6 gives PtCl
4:
:H
2PtCl
6 → PtCl
4 + 2 HCl
If excess acids are removed, PtCl
4 crystallizes from aqueous solutions in large red crystals of pentahydrate PtCl
4·5(H
2O), 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 PtCl
4.
Treatment of PtCl
4 with aqueous base gives the
6">t(OH)6sup>2− ion. With methyl
Grignard reagent
A Grignard reagent or Grignard compound is a chemical compound with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromide ...
s followed by partial hydrolysis, PtCl
4 converts to the cuboidal cluster
3)3(OH)">t(CH3)3(OH)sub>4.
[Greenwood, N. N.; & Earnshaw, A. (1997). ''Chemistry of the Elements'' (2nd Edn.), Oxford:Butterworth-Heinemann. .] Upon heating PtCl
4 evolves
chlorine
Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
to give
PtCl2:
:PtCl
4 → PtCl
2 + Cl
2
The heavier halides, PtBr
4 and PtI
4, are also known.
References
* Cotton, S. A. ''Chemistry of Precious Metals'', Chapman and Hall (London): 1997. .
Chlorides
Chlorides,4
Platinum group halides
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