OsO4 OSMIUM TETROXIDE - YELLOW

OSmium(IV) oxide (osmium tetroxide OSO4) A volatile yellow crystalline solid with a penetrating odor, used as an oxidizing agent and, in aqueous solution, as a catalyst for organic reactions. 

Oleic acid, C17H33.COOH, m.p. 6° C., is the most widely distributed of all the fatty acids. The free acid is a colourless liquid that turns yellow on exposure to air and light. It is a typical example of an unsaturated compound, and its presence in glycerides is shown by its property of reducing osmium tetroxide ( osmic acid ), OSO4, with the formation of a black deposit, easily recognised in histological preparations. 

The most interesting oxides of Ru and Os, however, are the volatile, yellow tetroxides, RUO4 (mp 25°C, bp 130°C< 3>) and OSO4 (mp 40°C, bp 130°C). They are tetrahedral molecules and the latter is perhaps the best-known compound of osmium. It is produced by aerial oxidation of the heated metal or by oxidizing other compounds of osmium with... 

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