Holmium(III) iodide

Holmium(III) iodide is an iodide of holmium, with the chemical formula of HoI3. It is used as a component of metal halide lamps.[5]

Holmium(III) iodide
Names
Other names
Holmium iodide
Holmium triiodide
Identifiers
3D model (JSmol)
ECHA InfoCard 100.034.050
EC Number
  • 237-470-3
  • InChI=1S/Ho.3HI/h;3*1H/q+3;;;/p-3
    Key: KXCRAPCRWWGWIW-UHFFFAOYSA-K
  • [Ho+3].[I-].[I-].[I-]
Properties
HoI3
Appearance Pale-yellow solid[1][2]
Density 5.4 g/cm3[3]
Melting point 994 °C[2]
Boiling point 1300 °C[4]
soluble in water[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Preparation

Holmium(III) iodide can be obtained by directly reacting holmium and iodine:[4]

2 Ho + 3 I2 → 2 HoI3

Holmium(III) iodide can also be obtained via the direct reaction between holmium and mercury(II) iodide:

2 Ho + 3 HgI2 → 2 HoI3 + 3 Hg

The mercury produced in the reaction can be removed by distillation.[6]

Holmium(III) iodide hydrate can be converted to the anhydrous form by dehydration with a large excess of ammonium iodide (since the compound is prone to hydrolysis).[4]

Properties

Holmium(III) iodide is a highly hygroscopic substance that dissolves in water.[7][3][2] It forms yellow hexagonal crystals with a crystal structure similar to bismuth(III) iodide.[4] In air, it quickly absorbs moisture and forms hydrates. The corresponding oxide iodide is also readily formed at elevated temperature.[4]

References
  1. Jantsch, G.; Jawurek, H.; Skalla, N.; Gawalowski, H. (1932). "Zur Kenntnis der Halogenide der seltenen Erden. VI. Über die Halogenide der Terbin- und Erbinerdengruppe" [Halides of the rare earths. VI. Halides of the terbium and erbium earth groups]. Zeitschrift für Anorganische und Allgemeine Chemie (in German). 207 (4): 353–367. doi:10.1002/zaac.19322070404.
  2. "13635 Holmium(III) iodide, ultra dry, 99.99% (REO)". Alfa Aesar. Retrieved 2022-08-20.
  3. Carl L. Yaws (2015). The Yaws Handbook of Physical Properties for Hydrocarbons and Chemicals. Gulf Professional Publishing. p. 301. ISBN 978-0128011461. Retrieved 2017-08-28.
  4. Georg Brauer (Hrsg.), unter Mitarbeit von Marianne Baudler u. a.: Handbuch der Präparativen Anorganischen Chemie. 3., umgearbeitete Auflage. Band I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6, S. 1077.
  5. Flesch, Peter G. (2007). Light and Light Sources: High-Intensity Discharge Lamps. Springer. p. 45. ISBN 978-3540326854.
  6. Asprey, L. B.; Keenan, T. K.; Kruse, F. H. (1964). "Preparation and crystal data for lanthanide and actinide triiodides". Inorganic Chemistry. 3 (8): 1137–1141. doi:10.1021/ic50018a015.
  7. "Holmium triiodide". WebElements. Retrieved 2022-08-20.
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