Thulium(III) iodide explained

Thulium(III) iodide is an iodide of thulium, with the chemical formula of TmI₃. Thulium(III) iodide is used as a component of metal halide lamps.^[1]

Preparation

Mercury(II) iodide can be heated with thulium to obtain thulium(III) iodide:^[2]

2 Tm + 3 HgI₂ → 2 TmI₃ + 3 Hg

The mercury produced in the reaction can be removed by distillation.^[3]

The thulium(III) iodide hydrate crystallized from solution can be heated with ammonium iodide to obtain the anhydrous form.^[4]

Properties

Thulium(III) iodide is a yellow, highly hygroscopic solid with a bismuth(III) iodide-type crystal structure. It forms in the hexagonal crystal system. Its hydrate can be heated in air to obtain TmOI. Its anhydrous form can be heated with thulium to obtain TmI₂:^[5]

2 TmI₃ + Tm → 3 TmI₂

Notes and References

1. Book: Peter G. . Flesch. Light and Light Sources: High-Intensity Discharge Lamps. Springer. 2007. 45. 9783540326847.
2. [Georg Brauer]
3. Asprey, L. B.; Keenan, T. K.; Kruse, F. H. Preparation and crystal data for lanthanide and actinide triiodides. Inorg. Chem., 1964. 3 (8): 1137-1240
4. 无机化学丛书 第七卷 钪 稀土元素. 科学出版社. pp 211
5. Divalent thulium. Thulium di-iodide. 32–35. Journal of Inorganic and Nuclear Chemistry. 13. 1–2. 2018-04-13. 10.1016/0022-1902(60)80232-1. L.B. Asprey, F.H. Kruse. 1960 . 2018-06-09. https://web.archive.org/web/20180609163225/https://linkinghub.elsevier.com/retrieve/pii/0022190260802321. live. （注：此文献指出Tm+HgI₂的反应生成TmI₂）