Osmium trichloride

Peracid oxidation of alkenes, catalyzed by osmium trichloride, produces a-ketols which are extremely versatile synthetic intermediates. The reaction occurs for a range of mono-and disubstituted alkenes (equation 42)176. 

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. 

A purer product is prepared by igniting ammonium chlorosmate, (NH4)20sCle, in chlorine at 350° C. Osmium trichloride, obtained by the foregoing method, is a brownish black, crystalline powder, which is hygroscopic and readily soluble in water, yielding a dark brown solution. This solution is stable even when boiled, although it possesses a slightly acid reaction. 

Osmium trichloride yields a series of double salts known as oamo-chlorides or chloroemitee, T I30sCI6. Of these the most important are the potassium and ammonium salts. 

Potassium Chlorosmate, K20sC16, is obtained by prolonged boiling of osmic acid with hydrochloric acid, and subsequent evaporation of the solution with potassium chloride. Dark brown crystals of the chlorosmate separate out, leaving osmium trichloride in solution. 

The green oolour is probably due to traces of osmium trichloride. 

Osmium Octachloride, OsCl8, appears to be formed in small quantity when chlorine is allowed to act upon heated osmium 3 as also when hydrated osmium trichloride, OsCl3.3HaO, is heated in a current of hydrogen. In this latter case, what is believed to be the octachloride is formed in minute quantities as a yellow sublimate.4... 

Osmium trichloride and Cu metal react with PF3 at 250 °C under 500 atm to give the colourless Os(PF3)5, for which a trigonal bipyramidal structure was inferred.433... 

Osmium trichloride-potassium ferrk Dihydroxylations. An efficient i couples and quinuclidine methanesulfot... 

Write the formulas for the following compounds and give the weight of one mole of each carbon disulfide, sulfur hexafluoride, nitrogen trichloride, osmium tetroxide. 

Manganese trichloride oxide, 4141 Manganese trifluoride, 4335 Mercury(II) bromide, 0269 Mercury(I) fluoride, 4312 Mercury(II) iodide, 4602 Molybdenum hexafluoride, 4365 Molybdenum pentachloride, 4180 Neptunium hexafluoride, 4366 Osmium hexafluoride, 4370 Palladium tetrafluoride, 4347 Palladium trifluoride, 4341... 

Manganese trichloride oxide, 4141 Mercury(I) oxide , 4613 Mercury(II) oxide, 4605 Molybdenum(IV) oxide, 4716 Molybdenum(VI) oxide, 4717 Nickel(II) oxide, 4821 Nickel(III) oxide, 4823 Nickel(IV) oxide, 4822 Niobium(V) oxide, 4818 Osmium(IV) oxide, 4833 Osmium(VIII) oxide, 4858 Palladium(II) oxide, 4825 Palladium(III) oxide, 4848 Palladium(IV) oxide, 4835... 

Other elements often separated from pile or cyclotron targets by distillation or volatilisation are tritium (3), germanium as the bromide (23), arsenic as the trichloride (67), technetium (23), (91), rhenium (24), (25) and osmium (25) as oxides. 

OSMIUM TETROXIDE - WHITE PHOSPHORUS - WHITE PHOSPHORUS TRICHLORIDE PHOSPHORUS PENTACHLORIDE PHOSPHINE... 

Phillips and Timms [599] described a less general method. They converted germanium and silicon in alloys into hydrides and further into chlorides by contact with gold trichloride. They performed GC on a column packed with 13% of silicone 702 on Celite with the use of a gas-density balance for detection. Juvet and Fischer [600] developed a special reactor coupled directly to the chromatographic column, in which they fluorinated metals in alloys, carbides, oxides, sulphides and salts. In these samples, they determined quantitatively uranium, sulphur, selenium, technetium, tungsten, molybdenum, rhenium, silicon, boron, osmium, vanadium, iridium and platinum as fluorides. They performed the analysis on a PTFE column packed with 15% of Kel-F oil No. 10 on Chromosorb T. Prior to analysis the column was conditioned with fluorine and chlorine trifluoride in order to remove moisture and reactive organic compounds. The thermal conductivity detector was equipped with nickel-coated filaments resistant to corrosion with metal fluorides. Fig. 5.34 illustrates the analysis of tungsten, rhenium and osmium fluorides by this method. 

All three metals yield dichlorides and trichlorides and, in the case of ruthenium and osmium, series of complex salts are known under the names of rutheno-ehlorides or ehlor-ruthenites, M2RuC15, and osmo-chlorides or chlor-osmites, M30sCle or MCKM20sC15. 

Some forty years before the discovery7 of ruthenium by Claus, it had been observed by Vauquelin that an azure blue colour is obtained by the action of zinc on certain solutions. This was attributed to the presence of osmium, but is now known to be a characteristic reaction for trivalent ruthenium. A similar colour is obtained by the action of hydrogen sulphide upon ruthenium trichloride, and wTas attributed by Claus and Joly 6 to reduction to the dichloride. This view is supported by Howe,7 who, however, has not succeeded in isolating the salt, but has obtained a derivative to which he gives the formula ... 

In 1910, Ruff and Bornemann3 definitely proved that osmium dichloride is capable of existence, for they prepared it by heating the trichloride to 500° C. under reduced pressure. 

Bisher konnten nur die Dichloride des Palladiums und Platins im festen Zustand hergestellt werden. Alle Versuche, durch thermischen Abbau der Trichloride oder direkte Chlorierung der Metalle zu den Dichloriden des Rutheniums, Rhodiums, Osmiums oder Iridiums zu gelangen, schlugen fehl (25, 27, 108). 

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. 

The unusual oxidant nickel peroxide converts aromatic aldehydes into carboxylic acids at 30-60 °C after 1.5-3 h in 58-100% yields [934. The oxidation of aldehydes to acids by pure ruthenium tetroxide results in very low yields [940. On the contrary, potassium ruthenate, prepared in situ from ruthenium trichloride and potassium persulfate in water and used in catalytic amounts, leads to a 99% yield of m-nitrobenzoic acid at room temperature after 2 h. Another oxidant, iodosobenzene in the presence of tris(triphenylphosphine)ruthenium dichloride, converts benzaldehyde into benzoic acid in 96% yield at room temperature [785]. The same reaction with a 91% yield is accomplished by treatment of benzaldehyde with osmium tetroxide as a catalyst and cumene hydroperoxide as a reoxidant [1163]. 

Cl3HuNsOi2Rh, Rhodium(III), hexaammine-, triperchlorate, 24 255 Cl3HuNsOs, Osmium(III), hexaammine-, trichloride, 24 273 CI3H0, Holmium chloride, 22 39 a3lrN4C4H,6 HCI 2H2O, Iridium(III),... 

The chloride derivative of the osmium compound is prepared in a similar fashion. The complex [Os3H3( 3-CCl)(CO)9] is obtained in 73% yield after a solution of [Os3H3(/i3-COCH3)(CO)9] and boron trichloride (obtained as a l.OM solution in CH2CI2) is stirred for 40 min, followed by the work-up described previously. 

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