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.[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]
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Other names
Potassium osmate(VI) dihydrate | |
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3D model (JSmol) |
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ECHA InfoCard | 100.157.189 |
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CompTox Dashboard (EPA) |
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Properties | |
H4K2O6Os | |
Molar mass | 368.42 |
Appearance | purple solid |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Infobox references | |
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 perosmates using alcohol:[5]
- 2 OsO4 + C2H5OH + 3 KOH → CH3CO2K + 2 K2[OsO2(OH)4]
Alkaline oxidative fusion of osmium metal also affords this salt.[1]
References
- F. Albert Cotton; Geoffrey Wilkinson (1966). Advanced Inorganic Chemistry: A Comprehensive Treatise. p. 1007.
- Li, Guigen; Chang, Han-Ting; Sharpless, K. Barry (1996). "Catalytic Asymmetric Aminohydroxylation (AA) of Olefins". Angew. Chem. Int. Ed. Engl. 35: 451–4. doi:10.1002/anie.199604511.CS1 maint: uses authors parameter (link)
- R. K. Murmann, C. L. Barnes "Redetermination of the crystal structure of potassium trans-(dioxo)-tetra(hydroxo)osmate(VI), K2[Os(OH)4(O)2]" Z. Kristallogr. NCS 217, 2002, pp. 303–304. doi:10.1524/ncrs.2002.217.jg.303
- Frémy, E. "Ueber das Osmium" Journal für Praktische Chemie 1844 vol.33, 406-416. doi: 10.1002/prac.18440330160
- John M. Malin (1980). "Potassium Tetrahydroxodioxoosmate(VI) and trans-Bis(Ethylenediamine)Dioxoosmium(VI) Chloride". Inorganic Syntheses. 20: 61–63. doi:10.1002/9780470132517.ch18.