Europium(II) iodide explained

Europium(II) iodide is the iodide salt of divalent europium cation.

Preparation

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

Reduction of europium(III) iodide with hydrogen gas at 350 °C:^[1]

Thermal decomposition of europium(III) iodide at 200 °C:^[1]

Reaction of europium with mercury(II) iodide:^[1]

Reaction of europium with ammonium iodide:^[1]

Structure

Europium(II) iodide has several polymorphs.^[2] It adopts a monoclinic crystal structure in space group P 2₁/c (no. 14).^{[3] [4]}

It also adopts an orthorhombic polymorph in space group Pbca (no. 61). This form is isostructural with strontium iodide.^[5]

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. This low-temperature phase is orthorhombic and in space group Pnma (no. 62). This is the same structure as modification IV of strontium iodide.^[6]

Notes and References

1. Book: Brauer, Georg. Georg Brauer. 1975. Handbook of Preparative Inorganic Chemistry. 3-432-02328-6.
2. Book: A. F. . Wells . Structural Inorganic Chemistry . 5th . 1984 . Oxford University Press . 978-0-19-965763-6 . 415–416 .
3. H. . Bärnighausen . Hartmut Bärnighausen . H. . Beck . H. W. . Grueninger . E. T. . Rietschel . N. . Schultz . Neue AB₂-strukturtypen mit siebenfach koordiniertem kation . . 1969 . 128 . 430 .
4. H. . Bärnighausen . N. . Schulz . Die Kristallstruktur der monoklinen Form von Europium(II)-jodid EuJ₂ . . 1969 . 25 . 1104–1110 . 10.1107/S0567740869003591 .
5. H. . Bärnighausen . H. P. . Beck . H. W. . Grueninger . Search Results - Access Structures . Rare Earths Mod. Sci. Technol. . 1971 . 9 . 74– .
6. M. . Krings . M. . Wessel . R. . Dronskowski . EuI₂, a low-temperature europium(II) iodide phase . . 2009 . 65 . i66–i68 . 10.1107/S0108270109038542 .