Osmium iodides

Osmium iodide refers to compounds of osmium with the formula OsIn. Several have been mentioned in the literature, but only the triiodide has been verified by X-ray crystallography.[1][2]

Osmium(I) iodide

Osmium(I) iodide is the iodide of osmium with the formula OsI. It is a metallic grey solid produced by the reaction of osmium tetroxide and hydroiodic acid heated in a water bath for 48 hours in a carbon dioxide atmosphere. This compound is amorphous.[2]

Osmium(II) iodide

Osmium(II) iodide is the iodide of osmium with the formula OsI2. It is a black solid[3] produced by the reaction of osmium tetroxide and hydroiodic acid at 250 °C in nitrogen:[2]

OsO4 + HI → OsI2 + H2O

This compound decomposes in contact with water.[3]

When a solution of osmium tetroxide in hydrochloric acid is reduced with potassium iodide, so-called osmium hydroiodide (OsI2•2HI) is formed,[4][5] which possesses a strong green color. It reacts with oxidizers such as hypoiodites to yield osmates.

OsO4 + 10HCl + 10KI → OsI2•2HI + 4H2O + 10KCl + 2I2

Osmium(III) iodide

Osmium(III) iodide is the iodide of osmium with the formula OsI3. This black solid is produced by heating hexaiodoosmic acid(H2OsI6).[2] This compound is insoluble in water.[3]

Osmium(IV) iodide

What was claimed to be osmium(IV) iodide was produced by the reaction of osmic acid (OsO2•2H2O) and hydroiodic acid.[6] However on attempted reproduction, this substance was found to be dihydroxonium hexaiodoosmate ((H3O+)2OsI62–). When heated this did not form a tetraiodo compound, and instead formed mono, di, and tri-iodo osmium compounds.[2]

References

  1. ^ Köhler, J. (2014). "Halides: Solid-State Chemistry". Encyclopedia of Inorganic and Bioinorganic Chemistry. pp. 1–22. doi:10.1002/9781119951438.eibc0078.pub2. ISBN 9781119951438.
  2. ^ a b c d e Fergusson, J. E.; Robinson, B. H.; Roper, W. R. (1962). "405. Iodides of osmium and rhenium". Journal of the Chemical Society (Resumed): 2113. doi:10.1039/JR9620002113.
  3. ^ a b c George K. Schweitzer; Lester L. Pesterfield (2009). The Aqueous Chemistry of the Elements (Ebook). Oxford University Press. p. 321. ISBN 9780199742196. Retrieved 11 November 2021.
  4. ^ J. Newton Friend (1920). "Osmium and its compounds". A textbook of inorganic chemistry, vol.IX Part I Cobalt, Nickel, and The Elements of The Platinum Group (PDF). London: Charles Griffin and Company, Limited. p. 218. Retrieved 17 June 2025.
  5. ^ Prakash Satya (2013). "Platinum Metals-IV:Osmium". Advanced Chemistry of Rare Elements, 5th Ed. India: S Chand and Company Limited. p. 710.
  6. ^ "The Chemistry of Osmium". the Sciences. Vol. 35, no. 904supp. Scientific American. 1893. pp. 14453–14454. doi:10.1038/scientificamerican04291893-14453supp.
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