Europium(II) iodide is the iodide salt of divalent

europium Europium is a chemical element with the symbol Eu and atomic number 63. Europium is the most reactive lanthanide by far, having to be stored under an inert fluid to protect it from atmospheric oxygen or moisture. Europium is also the softest lanth ...

cation.

Preparation

Europium(II) iodide can be prepared in a handful of ways, including:
Reduction of

europium(III) iodide Europium(III) iodide is an inorganic compound containing europium and iodine with the chemical formula . Preparation Europium metal reacts directly with iodine to form europium(III) iodide: : Hydrated europium(III) iodide can be prepared dissolv ...

with

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

gas at 350 °C: : Thermal decomposition of

at 200 °C: : Reaction of europium with

mercury(II) iodide Mercury(II) iodide is a chemical compound with the molecular formula Hg I2. It is typically produced synthetically but can also be found in nature as the extremely rare mineral coccinite. Unlike the related mercury(II) chloride it is hardly solu ...

: : Reaction of europium with ammonium iodide: :

Structure

Europium(II) iodide has several polymorphs. It adopts a

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystal, crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric pat ...

in space group P 2₁/c (no. 14). It also adopts an orthorhombic polymorph in space group ''Pbca'' (no. 61). This form is isostructural with strontium iodide. A third polymorph of europium(II) iodide is formed if it is prepared from europium and ammonium iodide at low temperatures (200 K) 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 wast ...

. This low-temperature phase is orthorhombic and in space group ''Pnma'' (no. 62). This is the same structure as modification IV of strontium iodide.

References

Europium(II) compounds Iodides Lanthanide halides {{Inorganic-compound-stub