Europium(III) iodide

Europium(III) iodide is an inorganic compound, a salt containing europium and iodine with the chemical formula EuI₃.^[1]

Europium(III) iodide^[1]

Names
IUPAC name Europium(III) iodide
Other names Europium triiodide
Identifiers
CAS Number	13759-90-5
3D model (JSmol)	Interactive image
ChemSpider	23349674
ECHA InfoCard	100.033.941
EC Number	244-721-0
PubChem CID	25210775
CompTox Dashboard (EPA)	DTXSID20929845
InChI InChI=1S/Eu.3HI/h;3*1H/q+3;;;/p-3 Key: OEGMUYNEEQNVBV-UHFFFAOYSA-K
SMILES [I-].[I-].[I-].[Eu+3]
Properties
Chemical formula	EuI 3
Molar mass	532.677 g mol−1
Appearance	colourless crystals[2]
Melting point	decomposes[1]
Structure[1][3][4]
Crystal structure	BiI3
Coordination geometry	octahedral
Related compounds
Other anions	EuF3, EuCl3, EuBr3
Other cations	SmI3, GdI3
Related compounds	EuI2
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

Europium metal reacts directly with iodine to form europium(III) iodide:^[5]

2 Eu + 3 I₂ → 2 EuI₃

Hydrated europium(III) iodide can be prepared dissolving europium(III) oxide or europium(III) carbonate in hydroiodic acid:^[1][6]

Eu₂O₃ + 6 HI + 6 H₂O → 2 EuI₃·9H₂O

Europium powder reacts with iodine in THF to form a THF adduct of europium(III) iodide:^[7][8]

2 Eu + 3 I₂ + 7 THF → [EuI₂(THF)₅][EuI₄(THF)₂]

The adduct can be formulated more simply as EuI₃(THF)_3.5.

Structure

Europium(III) iodide adopts the bismuth(III) iodide (BiI₃) crystal structure type,^[3][4] with octahedral coordination of each Eu³⁺ ion by 6 iodide ions.^[1]

Reactivity

Europium(III) iodide is used as the starting material for two of the main ways of preparing europium(II) iodide:^[9]

Reduction with hydrogen gas at 350 °C:

2 EuI₃ + H₂ → 2 EuI₂ + 2 HI

Thermal decomposition^[1] at 200 °C, a disproportionation reaction:

2 EuI₃ → 2 EuI₂ + 2 I₂

Europium(III) iodide nonahydrate, EuI₃·9H₂O, thermally decomposes to europium(II) iodide dihydrate, EuI₂·H₂O.^[10]