• Source: Potassium osmate

Potassium osmate is the inorganic compound with the formula K2[OsO2(OH)4]. This diamagnetic purple salt contains osmium in the VI (6+) oxidation state. When dissolved in water a red solution is formed. When dissolved in ethanol, the salt gives a pink solution, and it gives a blue solution when dissolved in methanol. The salt gained attention as a catalyst for the asymmetric dihydroxylation of olefins.




Structure


The complex anion is octahedral. Like related d2 dioxo complexes, the oxo ligands are trans. The Os=O and Os-OH distances are 1.75(2) and 1.99(2) Å, respectively. It is a relatively rare example of a metal oxo complex that obeys the 18e rule.




Preparation


The compound was first reported by Edmond Frémy in 1844. Potassium osmate is prepared by reducing osmium tetroxide with ethanol:

2 OsO4 + C2H5OH + 5 KOH → CH3CO2K + 2 K2[OsO2(OH)4]
Alkaline oxidative fusion of osmium metal also affords this salt.




See also


Sodium hexachloroosmate




References

Kata Kunci Pencarian:

• Potassium osmate
• AD-mix
• Osmium
• Sharpless asymmetric dihydroxylation
• Osmium tetroxide
• Diol
• Bisulfite
• Lurtotecan
• Danishefsky Taxol total synthesis