Osmium dioxide is aninorganic compound with theformulaOsO2. It exists as brown to black crystalline powder, but single crystals are golden and exhibit metallic conductivity. The compound crystallizes in therutile structural motif, i.e. the connectivity is very similar to that in the mineral rutile.
OsO2 can be obtained by the reaction ofosmium with a variety of oxidizing agents, including,sodium chlorate,osmium tetroxide, andnitric oxide at about 600 °C.[3][4] Usingchemical transport, one can obtain large crystals ofOsO2, sized up to 7x5x3 mm3. Single crystals show metallic resistivity of ~15 μΩ cm. A typical transport agent isO 2 via the reversible formation of volatileOsO4:[5]
OsO2 + O2 ⇌ OsO4
It can also be prepared by reducing osmium in higher oxidation states with alcohol, in which it forms a dihydrate. As opposed to the anhydrous dioxide, the dihydrate possesses a bluish black appearance.[6][7]
Compounds of osmium in the +6 oxidation state are dominated by the osmyl species, in whichOsO2 exists as a radical trans-dioxo moiety. These osmyl compounds are all diamagnetic, and stabilized by strong σ-donor and π-donor ligands. Most osmyl compounds are mononuclear and have a linear O=Os=O structure.[6][13]
^A. F. Holleman & E. Wiberg (2001).Inorganic chemistry. Academic Press. p. 1465.ISBN0-12-352651-5.
^Thiele G.; Woditsch P. (1969). "Neutronenbeugungsuntersuchungen am Osmium(IV)-oxid".Journal of the Less Common Metals.17 (4): 459.doi:10.1016/0022-5088(69)90074-5.
^Rogers, D. B.; Butler, S. R.; Shannon, R. D. (1972). "Single Crystals of Transition-Metal Dioxides".Inorganic Syntheses. Vol. XIII. pp. 135–145.doi:10.1002/9780470132449.ch27.ISBN9780470132449.
^Stopinski, Orin (September 1977)."Platinum-Group Metals"(PDF).Environmental Health Effects Research Series. Washington, DC: Environmental Protection Agency:85–86. Retrieved3 July 2025.
^J. E. Greedan; D. B. Willson; T. E. Haas (1968). "Metallic nature of osmium dioxide".Inorg. Chem.7 (11):2461–2463.doi:10.1021/ic50069a059.
^Yen, P (2004). "Growth and characterization ofOsO 2 single crystals".Journal of Crystal Growth.262 (1–4): 271.doi:10.1016/j.jcrysgro.2003.10.021.
