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Platinum(II) chloride
Names
	IUPAC name Platinum(II) chloride
	Other names Platinous chloride
Identifiers
CAS Number	10025-65-7 ;
3D model (JSmol)	monomer: Interactive image; hexamer: Interactive image;
ChEBI	CHEBI:49801 ;
ChemSpider	2668 ;
ECHA InfoCard	100.030.019
EC Number	233-034-1;
Gmelin Reference	1744965
PubChem CID	2770;
UNII	896SQ4TDHW ;
CompTox Dashboard (EPA)	DTXSID6064901 ;
	InChI InChI=1S/2ClH.Pt/h21H;/q;;+2/p-2 Key: CLSUSRZJUQMOHH-UHFFFAOYSA-L ; InChI=1/2ClH.Pt/h21H;/q;;+2/p-2 Key: CLSUSRZJUQMOHH-NUQVWONBAP;
	SMILES monomer: Cl[Pt]Cl; hexamer: [Cl+]0[Pt-2]12[Cl+][Pt-2]34[Cl+][Pt-2]05[Cl+][Pt-2]6([Cl+]1)[Cl+][Pt-2]([Cl+]2)([Cl+]3)[Cl+][Pt-2]([Cl+]4)([Cl+]5)[Cl+]6;
Properties
Chemical formula	PtCl2
Molar mass	265.99 g/mol
Appearance	dark brown powder
Density	6.05 g/cm3, solid
Melting point	581 °C (1,078 °F; 854 K)
Boiling point	decomposes
Solubility in water	insoluble
Solubility	insoluble in alcohol, ether ; soluble in HCl, ammonia
Magnetic susceptibility (χ)	−54.0·10−6 cm3/mol
Structure
Crystal structure	hexagonal
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314, H315, H317, H319, H334
Precautionary statements	P260, P261, P264, P272, P280, P285, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P304+P341, P305+P351+P338, P310, P321, P332+P313, P333+P313, P337+P313, P342+P311, P362, P363, P405, P501
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	3423 mg/kg (rat, oral)
Related compounds
Other anions	Platinum(II) bromide ; Platinum(II) sulfide
Other cations	Palladium(II) chloride
Related compounds	Platinum(IV) chloride
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Platinum(II) chloride describes the inorganic compounds with the formula Pt Cl₂. They are precursor used in the preparation of other platinum compounds. Platinum(II) chloride exists in two crystalline forms (polymorphs), but the main properties are somewhat similar: dark brown, insoluble in water, diamagnetic, and odorless.

Structure

The structures of PtCl₂ and PdCl₂ are similar. These dichlorides exist in both polymeric, or "α", and hexameric, or "β" structures. The β form converts to the α form at 500 °C. In the β form, the Pt-Pt distances are 3.32–3.40 Å, indicative of some bonding between the pairs of metals. In both forms of PtCl₂, each Pt center is four-coordinate, being surrounded by four chloride ligands. Complementarily, each Cl center is two-coordinate, being connected to two platinum atoms.^[2] The structure of α-PtCl₂ is reported to be disordered and contain edge- and/or corner-sharing square-planar PtCl₄ units.^[3]

Preparation

β-PtCl₂ is prepared by heating chloroplatinic acid to 350 °C in air.^[4]

H₂PtCl₆ → PtCl₂ + Cl₂ + 2 HCl

This method is convenient since the chloroplatinic acid is generated readily from Pt metal. Aqueous solutions of H₂PtCl₆ can also be reduced with hydrazinium salts, but this method is more laborious than the thermal route of Kerr and Schweizer.

Although PtCl₂ can form when platinum metal contacts hot chlorine gas, this process suffers from over-chlorination to give PtCl₄. Berzelius and later Wöhler and Streicher showed that upon heating to 450 °C, this Pt(IV) compound decomposes to the Pt(II) derivative:^[5]^[6]

PtCl₄ → PtCl₂ + Cl₂

Transformations such as this are "driven" by entropy, the free energy gained upon the release of a gaseous product from a solid. Upon heating to still higher temperatures, PtCl₂ releases more chlorine to give metallic Pt. This conversion is the basis of the gravimetric assay of the purity of the PtCl₂ product.

Reactions

Most reactions of PtCl₂ proceed via treatment with ligands (L) to give molecular derivatives. These transformations entail depolymerization via cleavage of Pt-Cl-Pt linkages:

PtCl₂ + 2 L → PtCl₂L₂

Addition of ammonia gives initially "PtCl₂(NH₃)₂", "Magnus's green salt", also described as [Pt(NH₃)₄][PtCl₄].

Many complexes have been described, the following are illustrative:^[7]

pink K₂PtCl₄, a widely employed water-soluble derivative.
colorless cis-PtCl₂(NH₃)₂, better known as cisplatin.
colorless cis-PtCl₂(P(C₆H₅)₃)₂, a common precursor to other complexes of the type PtX(Cl)(P(C₆H₅)₃)₂ (X = H, CH₃, etc.).
yellow trans-PtCl₂(P(C₆H₅)₃)₂, a metastable relative of the cis- isomer.
colorless dichloro(cycloocta-1,5-diene)platinum(II) (Pt(cod)Cl₂), an "organic-soluble" compound containing a labile organic ligand.

Several of these compounds are of interest in homogeneous catalysis in the service of organic synthesis or as anti-cancer drugs.

References

^ "Platinum(II) chloride". pubchem.ncbi.nlm.nih.gov. Retrieved 27 December 2021.
^ Holleman, A. F.; Wiberg, E. Inorganic Chemistry Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
^ Krebs, Bernt; Brendel, Claus; Schäfer, Harald (1988). "Neue Untersuchungen an α-Platindichlorid Darstellung und Struktur". Z. Anorg. Allg. Chem. 561 (1): 119–131. doi:10.1002/zaac.19885610113.
^ Kerr, G. T.; Schweizer, A. E. (2007). "β-Platinum(II) Chloride". Inorganic Syntheses. Vol. 20. pp. 48–49. doi:10.1002/9780470132517.ch14. ISBN 978-0-470-13251-7. {{cite book}}: |journal= ignored (help)
^ Wöhler, L.; Streicher, S. (1913). "Über das Beständigkeitsgebiet von vier wasserfreien Platinchloriden, über die Flüchtigkeit des Metalls im Chlorgas und die Darstellung sauerstoff-freien Chlors". Chem. Ber. 46 (2): 1591–1597. doi:10.1002/cber.19130460252.
^ A. E. Schweizer; G. T. Kerr (1978). "Thermal decomposition of hexachloroplatinic acid". Inorganic Chemistry. 17 (8): 2326–2327. doi:10.1021/ic50186a067.
^ Cotton, S. A. Chemistry of Precious Metals, Chapman and Hall (London): 1997. ISBN 0-7514-0413-6