Ammonium osmate

To separate osmium from ruthenium, the aqueous solution is acidified with nitric acid. While nitric acid oxidizes osmate ion to volatile osmium tetroxide, Os04, it converts ruthenium to a nitric oxide complex. Osmium tetroxide is removed from the solution by distillation in air and collected in an aqueous solution of caustic soda containing ethanol. Osmium tetroxide solution is heated with ammonium chloride, upon which osmium precipitates out as a complex chloride, 0s02(NH3)4Cl2. The precipitate is filtered, washed and decomposed by ignition with hydrogen to yield osmium metal. 

OS3C10H2O11, Osmium, decacarbonyl- -hydri-do-/i-hydroxotri-, 34 216 OS3C69O9, Osmium, nonacarbonyl(/i3- j. r] vq -fullerene-60)tri-, 34 226 Os3lrNOi3P2C49H3o, Iridate(l-), tridecacarbo-nyltriosmium-, bis(triphenylphosphoranyli-dene)ammonium, 34 208 OsgOgPCggHis, Osmium, octacarbonyl(triphe-nylphosphine) (fi -q q q -fullerene-60)tri-, 34 227 OS4C12H2K2O12, Osmate(2-),... 

Tetrammino-osmyl-sulphate, [0s02(NH3)4]SO4, may be prepared by mixing potassium osmate with ammonium sulphate. It is a yellow crystalline body which is sparingly soluble in cold water and decomposed by boiling water. 

The oxalate, [0s02(NH3)4]C204, is prepared in similar manner from potassium osmate and ammonium oxalate. It is a yellow crystalline substance. 

Pyrophoric Osmium Dioxide.—The oxide prepared by reduction of alkali osmates with alcohol or by hydrolysis of ammonium chlorosmate is not pure, but contains small quantities of organic substances or alkalies. When dry it is liable to ignite upon exposure to air, and even to detonate if warmed4 to 800° C. directly it meets the air. 

Potassium salts apparently do not behave in this way with halogen aoids, but are converted direotly into osmyl derivatives vide infra. If the above reaction is carried out in the warm, the ammonium salt is converted into the osmyl chloride or even to chlor osmate, (NHj),OsCl,. See p. 227. 

The chlor-platinates are mostly of a yellow colour, the insoluble salts, namely, those of potassium, rubidium, caesium, ammonium, and silver, crystallising in the anhydrous condition in the form of cubic octahedra, isomorphous with the chlor-iridates and chlor-osmates. The more soluble chlor-platinates, namely, those of sodium, magnesium, zinc, etc., crystallise with 6 molecules of water, and are isomorphous with the chlor-stannates.1... 

In the case of the syntheses of the osmium-containing species, reaction of ammonium hexachloro-osmate with two equivalents of 47 in refluxing ethylene glycol proceeded smoothly to yield the required 1 2 (Os ligand) intermediate directly in 40% yield. The higher kinetic inertness of osmium(II) complexes relative to those of ruthenium(II) may be the reason that the complexation could be stopped after the uptake of one metal ion in this synthesis. Once again, reaction of this intermediate with further metal ion(s) led to formation of the required mixed metal species (Figure 7.17). 

---