Magnus's green salt is the

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...

t(NH₃)₄PtCl₄]. This salt is named after

Heinrich Gustav Magnus Heinrich Gustav Magnus (; 2 May 1802 – 4 April 1870) was a German experimental scientist. His training was mostly in chemistry but his later research was mostly in physics. He spent the great bulk of his career at the University of Berlin, wher ...

, who, in the early 1830s, first reported the compound. The compound is a

linear chain compound 222px, Magnus's green salt is an example of a linear chain compound. In chemistry and materials science, linear chain compounds are materials composed of one-dimensional arrays of metal-metal bonded molecules or ions. Such materials exhibit an ...

, consisting of a chain of platinum atoms. It is dark green, which is unusual for platinum compounds.

Structure

This species has attracted interest in

materials chemistry Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries. The intellectual origins of materials scien ...

and

solid-state physics Solid-state physics is the study of rigid matter, or solids, through methods such as solid-state chemistry, quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state phy ...

because of its one-dimensional structure. It contains a chain of alternating tCl₄sup>2− anions and t(NH₃)₄sup>2+ cations, in which the platinum atoms are separated by 3.25 Å. It is a

semiconductor A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...

Preparation

The compound may be prepared by combining aqueous solutions of t(NH₃)₄sup>2+ and tCl₄sup>2−, which gives a deep green solid precipitate. Under some conditions, this reaction affords a pink polymorph of Magnus's green salt. In this so-called "Magnus's pink salt", the square planar Pt complexes are not stacked.

Related compounds

Magnus's green salt is one of three compounds with the

empirical formula In chemistry, the empirical formula of a chemical compound is the simplest whole number ratio of atoms present in a compound. A simple example of this concept is that the empirical formula of sulfur monoxide, or SO, is simply SO, as is the empir ...

, the others being

cisplatin Cisplatin is a chemical compound with chemical formula, formula ''cis''-. It is a coordination complex of platinum that is used as a chemotherapy medication used to treat a number of cancers. These include testicular cancer, ovarian cancer, c ...

(an important

anticancer drug Chemotherapy (often abbreviated chemo, sometimes CTX and CTx) is the type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) in a standard regimen. Chemotherapy may be given with a cu ...

) and

transplatin ''trans''-Dichlorodiammineplatinum(II) is the trans isomer of the coordination complex with the formula ''trans''-PtCl2(NH3)2, sometimes called ''transplatin''. It is a yellow solid with low solubility in water but good solubility in DMF. The ex ...

. These ''cis'' and ''trans'' compounds are molecules, whereas Magnus's green salt is a polymer. This difference is manifested by the solubility of the molecular complexes in water, whereas Magnus's green salt is insoluble. Magnus's green salt occurred as an impurity in early routes to cisplatin from

potassium tetrachloroplatinate Potassium tetrachloroplatinate(II) is the chemical compound with the chemical formula, formula K2PtCl4. This reddish orange salt (chemistry), salt is an important reagent for the preparation of other Complex (chemistry), coordination complexes of ...

. Modern production avoids contamination by first converting the tetrachloroplatinate to

potassium tetraiodoplatinate Potassium tetraiodoplatinate is the inorganic compound with the formula . It is the potassium salt of tetraiodoplatinate, a square planar complex of platinum(II). The compound crystallizes from water as the dihydrate, whereas the related chlorid ...

, as the iodo

ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...

's stronger

trans effect In inorganic chemistry, the trans effect is the increased Lability#Chemistry, lability of ligands that are Cis-trans isomerism#Inorganic coordination complexes, trans to certain other ligands, which can thus be regarded as trans-directing ligands. ...

favors the ''cis'' molecule over the polymeric salt. Soluble analogues of Magnus's green salt can be prepared by replacing the ammonia with ethylhexylamine. The corresponding palladium compound ( d(NH₃)₄PdCl₄]) is known as " Louis Nicolas Vauquelin, Vauquelin’s salt".

History

Magnus's green salt was one of the first examples of a

metal ammine complex In coordination chemistry, metal ammine complexes are metal complexes containing at least one ammonia () ligand. "Ammine" is spelled this way for historical reasons; in contrast, alkyl or aryl bearing ligands are spelt with a single "m". Almost al ...

References

{{DEFAULTSORT:Magnus's green salt Platinum(II) compounds Metal halides Ammine complexes Chloro complexes Inorganic polymers