Cerium diiodide is an

iodide An iodide ion is the ion 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 defic ...

cerium Cerium is a chemical element with the symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the +3 o ...

, with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

of CeI₂.

Preparation

Cerium diiodide can be obtained from the reduction of

cerium(III) iodide Cerium(III) iodide (CeI3) is the compound formed by cerium(III) cations and iodide An iodide ion is the ion I−. Compounds with iodine in formal oxidation state −1 are called iodides. In everyday life, iodide is most commonly encountered a ...

with metallic

under vacuum at 800 °C to 900 °C. : It can also be formed from the reaction of cerium and

ammonium iodide Ammonium iodide is the chemical compound NH4I. It is used in photographic chemicals and some medications.Holleman, A. F.; Wiberg, E. ''Inorganic Chemistry'' Academic Press: San Diego, 2001. . It can be prepared by the action of hydroiodic acid on a ...

in liquid

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...

at −78 °C. The reaction forms an ammonia complex of cerium diiodide, which decomposes to cerium diiodide under vacuum at 200 °C. : It was first created by John D. Corbett in 1961.

Properties

Cerium diiodide is an opaque dark solid with a metal-like appearance and properties. There is no cerium(II) in cerium diiodide, and its real structure is Ce³⁺(I⁻)₂e⁻. It is easily

hydrolyzed Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...

to form the corresponding iodide oxide. Like lanthanum diiodide and praseodymium diiodide, the cerium diiodide forms in the MoSi₂-type structure, with

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it unchan ...

''I''4/''mmm'' (No. 139).

References

{{Lanthanide halides Cerium compounds Iodides Substances discovered in the 1960s Electrides