Osmium tetroxide

Osmium(VIII) oxide (OsO4)

Physical properties

• monoclinic crystals

• sublimes at room temperature

• pure osmium(VIII) oxide is probably colorless (yellow hue is due to OsO2

impurities)

• OsO4 is 518 times more soluble in carbon tetrachloride than in water.

Physical properties

Synthesis

• OsO4 is formed slowly when osmium powder reacts with O2 at ambient

temperature. Reaction of bulk solid requires heating to 400 °C

• Os + 2 O2 → OsO4

Uses

• Organic synthesis

• Biological staining

• Polymer staining

• Osmeth

• Osmium ore refining

• Buckminsterfullerene adduct

Organic synthesis

• widely used to oxidise alkenes to the vicinal diols

• In combination with sodium periodate, OsO4 is used for the oxidative cleavage of alkenes

Biological staining

• widely used staining agent used in TEM to provide contrast to the image

Osmeth

• OsO4 can be recycled and stored in the form of osmeth

• OsO4 complexed with hexamine

• Use to make solution of OsO4

Osmium ore refining

• intermediate in osmium ore refining

Buckminsterfullerene adduct

• formed from a derivative of OsO4, was C60(OsO4)(4-tert-butylpyridine)2

• The adduct broke the fullerene's symmetry allowing for crystallization and confirmation of the structure of C60