Manganese(II) iodide is the

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

composed of

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

and

iodide An iodide ion is I−. Compounds with iodine in formal oxidation state −1 are called iodides. In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. Worldwide, iodine deficiency ...

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 ...

MnI₂(H2O)_n. The tetrahydrate is a pink solid while the anhydrous derivative is beige. Both forms feature

octahedral In geometry, an octahedron (: octahedra or octahedrons) is any polyhedron with eight faces. One special case is the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex. Many types of i ...

Mn centers. Unlike MnCl₂(H₂O)₄ and MnBr₂(H₂O)₄ which are cis, MnI₂(H₂O)₄ is trans.

Preparation

Anhydrous MnI₂ is prepared from the elements: : The tetrahydrate can be prepared by treating

manganese(II) carbonate Manganese carbonate is a compound with the chemical formula Mn CO3. Manganese carbonate occurs naturally as the mineral rhodochrosite but it is typically produced industrially. It is a pale pink, water-insoluble solid. Approximately 20,000 met ...

with

hydriodic acid Hydroiodic acid (or hydriodic acid) is a colorless liquid. It is an aqueous solution of hydrogen iodide with the chemical formula . It is a strong acid, in which hydrogen iodide is ionized completely in an aqueous solution. Concentrated aqueou ...

. The anhydrous form can be produced from it by dehydration in a vacuum.

Properties

Samples turn brown in air under the influence of light as a result of the oxidation of the iodide ion to iodine. It has a trigonal crystal structure of the

cadmium iodide Cadmium iodide is an inorganic compound with the formula CdI2. It is a white hygroscopic solid. It also can be obtained as a mono- and tetrahydrate. It has few applications. It is notable for its crystal structure, which is typical for compounds ...

type (polytype 2H) with the space group Pm1 (space group no. 164). It dissolves in water and decomposes. The tetrahydrate has a monoclinic crystal structure with the space group P2₁''/c'' (No. 14).

Applications

It is often used in the lighting industry.

References

{{DEFAULTSORT:Manganese(Ii) Iodide Manganese(II) compounds Iodides Metal halides