Potassium osmate is the
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
with the formula K
2 sO2(OH)4 This diamagnetic purple
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
contains osmium in the VI (6+) oxidation state.
When dissolved in water a pink solution is formed but when dissolved in methanol, the salt gives a blue solution.
[ The salt gained attention as a catalyst for the asymmetric dihydroxylation of olefins.
]
Structure
The complex anion is octahedral
In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at ea ...
. 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
A transition metal oxo complex is a coordination complex containing an oxo ligand. Formally O2-, an oxo ligand can be bound to one or more metal centers, i.e. it can exist as a terminal or (most commonly) as bridging ligands (Fig. 1). Oxo ligan ...
that obeys the 18e rule.
Preparation
The compound was first reported by Edmond Frémy
Edmond Frémy (; 28 February 1814 – 3 February 1894) was a French chemist. He is perhaps best known today for Frémy's salt, a strong oxidizing agent which he discovered in 1845. Fremy's salt is a long-lived free radical that finds use as a s ...
in 1844. Potassium osmate is prepared by reducing osmium tetroxide
Osmium tetroxide (also osmium(VIII) oxide) is the chemical compound with the formula OsO4. The compound is noteworthy for its many uses, despite its toxicity and the rarity of osmium. It also has a number of unusual properties, one being that the ...
with ethanol:[
]
See also
*Sodium hexachloroosmate
Sodium hexachloroosmate is the inorganic compound with the formula . A red solid, it is the disodium salt of the osmium(VI) complex . The anion is an octahedral complex with Os-Cl distance of 2.325(3) Å, as established by X-ray crystallography. ...
References
{{Osmium compounds
Osmium compounds
Oxides
Potassium compounds
Transition metal oxyanions