Osmium tetrachloride

Osmium tetroxide is obtained as an intermediate during recovery of osmium metal from osmiridium or other noble metal minerals (See Osmium). In general, oxidation of an aqueous solution of an osmium salt or complex, such as sodium osmate with nitric acid, yields the volatile tetroxide which may be distilled out from the solution. In the laboratory, the compound can be prepared by oxidation of the osmium tetrachloride, OsCh, or other halide solutions with sodium hypochlorite followed by distdlation. 

Osmium Trichloride, OsC.l3, is obtained1 by heating osmium, obtained by reduction of the dioxide in hydrogen, in chlorine at about 1050° C., and cooling the vapour rapidly. It then contains some admixed osmium tetrachloride. 

Osmium Tetrachloride, OsCl4, is obtained as a reddish brown sublimate when metallic osmium is heated in chlorine (Berzelius) between 650° and 700° C.1... 

Osmium tetrachloride yields a series of double salts known as osmichlorides or chlorosmates, M2OsClg. Of these the potassium, sodium, and ammonium salts are best known. 

Osmium tetrachloride is formed when an excess of Cl2 is used at temperatures above 650°C otherwise a mixture with the trichloride is formed. The latter is obtained when OsC is decomposed at 470°C in a flow system with a low pressure of chlorine. Osmium tetrachloride in its orthorhombic high-temperature form has infinite chains of octahedra sharing opposite edges with no structural indication of metal-metal bonding. 

Osmocene, Os( sHo)2, has recently been made, in 20% yield, by the interaction of cyclopentadienyl sodium and osmium tetrachloride (47). It forms colorless crystals which melt at 230° again, it dissolves in organic solvents water, however, has no action on it, nor does it dissolve. The hydrogen atoms in the cyclopentadienyl rings, like those in ferrocene and ruthenocene, can undergo substitution this property has not been described for other metal cyclopentadienyl compounds, except in one... 

Osmium(viii).—From studies of the extraction of OSO4 from alkaline aqueous solutions by carbon tetrachloride, it has been suggested that the anion [0s04(0H)] may exist in these media. Similar evidence was found for the presence of [OsOjN]" in aqueous ammonia solutions of 0s04. Examination of the i.r. spectra of a series of metal complexes of the ligand 8-amino-7-hydroxy-4-methylcoumarin, including [OsO LjjClj, indicate a correlation between certain vibrational bands, e.g. v(M—N), and the stability of the compounds. ... 

Elemental composition Os 74.82%, 0 25.18%. The compound can be identified by its physical properties, such as, odor, color, density, melting-, and boiling points. Its acrid odor is perceptible at concentrations of 0.02 mg/hter in air. The oxide also produces an orange color when a small amount of the compound or its aqueous solution is mixed with an aqueous solution of ammonia in KOH (see Reactions). Aqueous solution of the tetroxide may be analyzed for osmium by AA or ICP spectrometry (see Osmium). Vapors of the tetroxide may be purged from an aqueous solution by helium, adsorbed over a trap, and desorbed thermally by helium onto a GC. Alternatively, a benzene or carbon tetrachloride solution may be injected onto the GC and the compound peak identified by mass spectrometry. The characteristic mass ions for its identification should be 190 and 254. 

Ruthenium tetraoxide is a powerful oxidant it is more reactive than osmium tetraoxide, and combines explosively with ether or benzene, so that it is generally used as a dilute solution in carbon tetrachloride. Beynon et al.155 first demonstrated the usefulness of this reagent in carbohydrate chemistry by converting methyl 4,6-0-benzylidene-2-deoxy-a-D-n bo- and -D-uraZu rao-hexopyranosides into methyl 4,6-0-benzylidene-2-deoxy-a-D-eryt/zro-hexopyranosid-3-ulose. 

On the other hand, iridium yields a tetrachloride, IrCl4, and this, with chlorides of the alkali metals, produces a series of salts known as hexachlor-iridates, of general formula M2IrClG, isomorphous with the analogous derivatives of osmium, ruthenium, palladium, and platinum. These form an interesting link between these metals. 

Fluorine is without action in the cold, but upon warming combination takes place. Chlorine attacks osmium at high temperatures, the tetrachloride, OsC l4. resulting at 650° to 700° C. Bromine vapour, however, is without action upon the metal.1... 

When heated with potassium chloride in a current of chlorine, osmium yields the tetrachloride, OsCl4. 

It is particularly hazardous to the eyes because of its ready reaction with organic matter, a property exploited in electron microscopy in order to stain and fix biological tissues. Although osmium is a d8 transition metal, its tetroxide is a coordinatively unsaturated 16-electron species and has a tetrahedral structure3. It is highly soluble in carbon tetrachloride (375 g/ 100 g), less so in benzene, and moderately soluble in water (7.24 g/100 g). 

This procedure has been used to prepare many other chlorides, e.g., tungsten hexachloride, vanadium tetrachloride, and the pentachlorides of niobium and tantalum. However, it is normally much easier to prepare chlorides than fluorides. This method will therefore find application only where this generalization is not applicable. In particular, it will find application where the chloride is thermally unstable under normal chlorination conditions and must be prepared at or below room temperature. This method has been used to advantage for the preparation of ReCle and the new compound osmium pentachloride. ... 

The tetrafiuorides are yellow solids, probably polymeric, and are obtained by reducing RuF with Ij, and OsFg with W(CO)6. The tetrachloride and tetrabromide of osmium require pressure as well as heat in their preparations from the... 

Osmium(VI) tetrachloride oxide OSOCI4 36609-16-6 348.04 dark brn hyg cry 32 200 reac FIjO s he... 

The metals osmium and ruthenium can be selectively oxidized to their tetroxides and separated by extraction with carbon tetrachloride [24]. Reference 24 also deals with enrichment procedures of palladium, rhodium, iridium, and platinum chloro complexes from hydrochloric acid solutions... 

A few distributions of VCM suspensions in water viewed by light microscopy into specially designed pressure cells appear in the literature (23,24), but no analyses of droplet size distribution under different conditions of reactor agitation or polymeric additive addition have been reported. A technique for fixing VCM emulsions by osmium tetroxide (25) may prove useful to study the VCM/water system in greater detail. Mersmann and Grossmann (26) have studied the dispersion of liquids in non-miscible two-phase systems, which include chlorinated liquids such as carbon tetrachloride in water. The influence of stirrer type and speed on the development of an equilibrium droplet size distribution is discussed. Different empirical relationships to calculate the Sauter mean diameter of droplet distributions from reactor operating parameters are also reviewed. 

Following the report last year of the first vicinal oxyamination of olefins using aminated derivatives of osmium tetroxide. Sharpless has extended this analogy to oxidations involving selenium dioxide. Two aza analogues of selenium dioxide have been prepared by either the reaction of selenium tetrachloride with the amine or... 

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