Osmium chlorides

The product is a brownish-yellow powder, readily soluble in pyridine, aqueous alkalis, and methyl alcohol. The hydrochloride yields a yellowiah-brown addition product with gold chloride and a brownish-green compound with osmium chloride, these being soluble in water but insoluble in ether. 

AMMONIUM RHOOMH NITRATE. (NM4V HN02 4 rutncnimm cNLORioe, OSMIUM chloride IRIOIUM POWDER SILVCR CRYSTALS. 

Rinehart et al. [1, 2] and Michelotti and Keaveney [3] reported the first successful emulsion ROMP using water-soluble ruthenium, iridium, and osmium chlorides activated by a reducing agent. These ill-defined catalyst systems were... 

Oxidation. Maleic and fumaric acids are oxidized in aqueous solution by ozone [10028-15-6] (qv) (85). Products of the reaction include glyoxyhc acid [298-12-4], oxalic acid [144-62-7], and formic acid [64-18-6], Catalytic oxidation of aqueous maleic acid occurs with hydrogen peroxide [7722-84-1] in the presence of sodium tungstate(VI) [13472-45-2] (86) and sodium molybdate(VI) [7631-95-0] (87). Both catalyst systems avoid formation of tartaric acid [133-37-9] and produce i j -epoxysuccinic acid [16533-72-5] at pH values above 5. The reaction of maleic anhydride and hydrogen peroxide in an inert solvent (methylene chloride [75-09-2]) gives permaleic acid [4565-24-6], HOOC—CH=CH—CO H (88) which is useful in Baeyer-ViUiger reactions. Both maleate and fumarate [142-42-7] are hydroxylated to tartaric acid using an osmium tetroxide [20816-12-0]/io 2LX.e [15454-31 -6] catalyst system (89). 

The PGM concentrate is attacked with aqua regia to dissolve gold, platinum, and palladium. The more insoluble metals, iridium, rhodium, mthenium, and osmium remain as a residue. Gold is recovered from the aqua regia solution either by reduction to the metallic form with ferrous salts or by solvent-extraction methods. The solution is then treated with ammonium chloride to produce a precipitate of ammonium hexachloroplatinate(IV),... 

The residue, which contains Ir, Ru, and Os, is fused with sodium peroxide at 500°C, forming soluble sodium mthenate and sodium osmate. Reaction of these salts with chlorine produces volatile tetroxides, which are separated from the reaction medium by distillation and absorbed into hydrochloric acid. The osmium can then be separated from the mthenium by boiling the chloride solution with nitric acid. Osmium forms volatile osmium tetroxide mthenium remains in solution. Ruthenium and osmium can thus be separately purified and reduced to give the metals. 

Other Metals. Ruthenium, the least expensive of the platinum group, is the second best electrical conductor, has the hardest deposit, and has a high melting point. A general purpose bath uses 5.3 g/L of mthenium as the sulfamate salt with 8 g/L sulfamic acid, and is operated at 25—60°C with a pH of 1—2. Osmium has been plated from acid chloride solutions (130) and iridium from bromide solutions, but there are no known appHcations for these baths. 

Selective hydroxylation with osmium tetroxide (one equivalent in ether-pyridine at 0 ) converts (27) to a solid mixture of stereoisomeric diols (28a) which can be converted to the corresponding secondary monotoluene-sulfonate (28b) by treatment with /7-toluenesulfonyl chloride in methylene dichloride-pyridine and then by pinacol rearrangement in tetrahydrofuran-lithium perchlorate -calcium carbonate into the unconjugated cyclohepte-none (29) in 41-48 % over-all yield from (27). Mild acid-catalyzed hydrolysis of the ketal-ketone (29) removes the ketal more drastic conditions by heating at 100° in 2 hydrochloric acid for 24 hr gives the conjugated diketone (30). 

Hydroxycortisone BMD) (48) A solution of 4 g of 17a,20 20,21-bis-methylenedioxypregn-4-ene-3,l 1-dione (cortisone BMD) (46) dissolved in 300 ml of t-butanol and 5 ml of water is treated with 34 ml of 35 % hydrogen peroxide and 0.45 g of osmium tetroxide predissolved in 36 ml of /-butanol. The resulting mixture is allowed to stand at room temperature for 2 days. Diol (47) which crystallizes during the reaction is collected by filtration and washed with /-butanol and water. The filtrate is diluted with ethyl acetate and washed sequentially with aqueous sodium chloride, aqueous 10% sodium bisulfite, aqueous 10% sodium bicarbonate and finally with water to neutrality. The solvent is evaporated and a second crop of the diol (47) is collected, providing a total of about 3.8 g. 

Unlike ruthenium (and other platinum metals) osmium forms chlorides and bromides in a range of oxidation states [11,12]. 

It has 6-coordinate osmium in a structure (Figure 1.2) regarded as being made from a hexagonally packed array of chlorides with osmiums occupying half the holes in alternate layers Os-Cl bond lengths are 2.261 A (terminal) and 2.378 A (bridge) [20]. 

Mit Nickel(II)-, Osmium(IV)-, Iridium(III)- und Platin(II)-chlorid werden ahnliche Ergebnisse erzielt. In Gegenwart von Raney-Nickel geniigt ein 100°/oiger Natriumbora-nat-t)berschu63. 

The structure of the styryl derivative Os ( ,)-CH=CHPh Cl(CO)(PIPr3)2 has been determined by X-ray diffraction analysis.33 In agreement with OsHCl(CO) (P Pr3)2, the coordination polyhedron around the osmium atom can be rationalized as square-pyramidal with the phosphines, mutually tram disposed, the chloride and the carbonyl group occupying the basal sites, and the alkenyl located at the... 

The formation of these compounds has been rationalized according to Scheme 6. The reaction of Os (E )-CH=C 11 Ph C1 (C())( P Pr3)2 with n-BuLi involves replacement of the chloride anion by a butyl group to afford the intermediate Os (/i> CH=CHPh ( -Bu)(CO)(P Pr3)2, which by subsequent hydrogen (3 elimination gives OsH ( >CI I=CHPh (CO)( P Pr3)2. The intramolecular reductive elimination of styrene from this compound followed by the C—H activation of the o-aryl proton leads to the hydride-aryl species via the styrene-osmium(O) intermediate Os r 2-CH2=CHPh (CO)(P Pr3)2. In spite of the fact that the hydride-aryl complex is the only species detected in solution, the formation of OsH ( )-CH=CHPh L(CO)(P Pr3)2 and 0s ( )-CH=CHPh (K2-02CH)(C0)(P,Pr3)2 suggests that in solution the hydride-aryl complex is in equilibrium with undetectable concentrations of OsH ( )-CH=CHPh (CO)(P,Pr3)2. This implies that the olehn-osmium(O) intermediate is easily accessible and can give rise to activation reactions at both the olefinic and the ortho phenyl C—H bonds of the... 

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