OsO2 Osmium oxide

Ruthenium and osmium have no oxides comparable to those of iron and, indeed, the lowest oxidation state in which they form oxides is 4-4. Ru02 is a blue to black solid, obtained by direct action of the elements at 1000°C, and has the rutile (p. 961) structure. The intense colour has been suggested as arising from the presence of small amounts of Ru in another oxidation state, possibly 4-3. OSO2 is a yellowish-brown solid, usually prepared by heating the metal at 650°C in NO. It, too, has the rutile structure. 

Of the oxides of osmium, OsO, OS2O3, OSO2 and OSO4, the first three are basic in water, the last one nearly neutral or slightly acidic. 

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