potassium osmate
{{Chembox
| ImageFile = K2OsO2(OH)4.png
| ImageSize =
| ImageAlt =
| ImageFile1 = Potassium osmate(VI) dihydrate.jpg
| IUPACName =
| OtherNames = Potassium osmate(VI) dihydrate
|Section1={{Chembox Identifiers
| CASNo = 10022-66-9
| ChemSpiderID = 21241360
| EINECS = 243-247-1
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 5M2BWQ2TYJ
| PubChem = 53393272
| SMILES = [K+].[K+].[O-][Os](O)(O)(O)(O)[O-]
| StdInChI = InChI=1S/2K.4H2O.2O.Os/h;;4*1H2;;;/q2*+1;;;;;2*-1;+4/p-4
| StdInChIKey = DDTIHYGDUUGVNU-UHFFFAOYSA-J
}}
|Section2={{Chembox Properties
| Formula = H4K2O6Os
| MolarMass = 368.42
| Appearance = purple solid
| Density =
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|Section3={{Chembox Hazards
| GHSPictograms = {{GHS06}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|301|311|330|331}}
| PPhrases = {{P-phrases|260|261|264|270|271|280|284|301+310|302+352|304+340|310|311|312|320|321|322|330|361|363|403+233|405|501}}
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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.{{cite book|title=Advanced Inorganic Chemistry: A Comprehensive Treatise|url=https://archive.org/details/advancedinorgani00cott|url-access=registration|author1=F. Albert Cotton|author-link=F. Albert Cotton|author2=Geoffrey Wilkinson|author2-link=Geoffrey Wilkinson|year=1966|page=[https://archive.org/details/advancedinorgani00cott/page/1007 1007]|publisher=New York, Interscience Publishers }} When dissolved in water a red solution is formed. When dissolved in dilute alcohols, 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.{{cite journal|author1=Li, Guigen |author2=Chang, Han-Ting |author3=Sharpless, K. Barry |title=Catalytic Asymmetric Aminohydroxylation (AA) of Olefins|journal=Angew. Chem. Int. Ed. Engl.|year=1996|volume=35|issue=4 |pages=451–4|doi=10.1002/anie.199604511}}
Structure
The complex anion is octahedral. Like related d2 dioxo complexes, the oxo ligands are trans.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}} 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.Frémy, E. "Ueber das Osmium" Journal für Praktische Chemie 1844 vol.33, 406-416. {{doi| 10.1002/prac.18440330160}} Potassium osmate is prepared by reducing osmium tetroxide with ethanol:{{cite book|title=Potassium Tetrahydroxodioxoosmate(VI) and trans-Bis(Ethylenediamine)Dioxoosmium(VI) Chloride|series=Inorganic Syntheses|volume=20|year=1980|author=John M. Malin|chapter=Potassium Tetrahydroxodioxoosmate(VI) and trans ‐Bis(Ethylenediamine)Dioxoosmium(VI) Chloride |pages=61–63|doi =10.1002/9780470132517.ch18|isbn=9780470132517}}
:2 OsO4 + C2H5OH + 5 KOH → CH3CO2K + 2 K2[OsO2(OH)4]
Alkaline oxidative fusion of osmium metal also affords this salt.
See also
References
{{Reflist}}
{{potassium compounds}}
{{Osmium compounds}}