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Potassium osmate

Names
Other names Potassium osmate(VI) dihydrate
Identifiers
CAS Number	10022-66-9
3D model (JSmol)	Interactive image
ChemSpider	21241360
ECHA InfoCard	100.157.189
EC Number	243-247-1
PubChem CID	53393272
UNII	5M2BWQ2TYJ
CompTox Dashboard (EPA)	DTXSID80693853
InChI InChI=1S/2K.4H2O.2O.Os/h;;4*1H2;;;/q2*+1;;;;;2*-1;+4/p-4Key: DDTIHYGDUUGVNU-UHFFFAOYSA-J
SMILES ..(O)(O)(O)(O)
Properties
Chemical formula	H4K2O6Os
Molar mass	368.42
Appearance	purple solid
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H311, H330, H331
Precautionary statements	P260, P261, P264, P270, P271, P280, P284, P301+P310, P302+P352, P304+P340, P310, P311, P312, P320, P321, P322, P330, P361, P363, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references

Potassium osmate is the inorganic compound with the formula K₂. 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 d 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

Alkaline oxidative fusion of osmium metal also affords this salt.

See also

• Sodium hexachloroosmate

References

1. ^ F. Albert Cotton; Geoffrey Wilkinson (1966). Advanced Inorganic Chemistry: A Comprehensive Treatise. New York, Interscience Publishers. p. 1007.
2. Li, Guigen; Chang, Han-Ting; Sharpless, K. Barry (1996). "Catalytic Asymmetric Aminohydroxylation (AA) of Olefins". Angew. Chem. Int. Ed. Engl. 35 (4): 451–4. doi:10.1002/anie.199604511.
3. R. K. Murmann, C. L. Barnes "Redetermination of the crystal structure of potassium trans-(dioxo)-tetra(hydroxo)osmate(VI), K₂" Z. Kristallogr. NCS 217, 2002, pp. 303–304. doi:10.1524/ncrs.2002.217.jg.303
4. Frémy, E. "Ueber das Osmium" Journal für Praktische Chemie 1844 vol.33, 406-416. doi:10.1002/prac.18440330160
5. John M. Malin (1980). "Potassium Tetrahydroxodioxoosmate(VI) and trans ‐Bis(Ethylenediamine)Dioxoosmium(VI) Chloride". Potassium Tetrahydroxodioxoosmate(VI) and trans-Bis(Ethylenediamine)Dioxoosmium(VI) Chloride. Inorganic Syntheses. Vol. 20. pp. 61–63. doi:10.1002/9780470132517.ch18. ISBN 9780470132517.

• Osmium compounds
• Oxides
• Potassium compounds
• Transition metal oxyanions