Potassium osmate

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 Y
CompTox Dashboard (EPA)	DTXSID80693853
InChI InChI=1S/2K.4H2O.2O.Os/h;;4*1H2;;;/q2*+1;;;;;2*-1;+4/p-4 Key: DDTIHYGDUUGVNU-UHFFFAOYSA-J
SMILES [K+].[K+].[O-][Os](O)(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 [77 °F], 100 kPa). Infobox references

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.^[1] When dissolved in water a pink solution is formed but when dissolved in methanol, the salt gives a blue solution.^[1] The salt gained attention as a catalyst for the asymmetric dihydroxylation of olefins.^[2]

Structure

The complex anion is octahedral. Like related d² dioxo complexes, the oxo ligands are trans.^[3] 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.^[4] Potassium osmate is prepared by reducing osmium tetroxide with ethanol:^[5]

2 OsO₄ + C₂H₅OH + 5 KOH → CH₃CO₂K + 2 K₂[OsO₂(OH)₄]

Alkaline oxidative fusion of osmium metal also affords this salt.^[1]

See also

• Sodium hexachloroosmate

References