Ammonium Hexachloroosmate IV

Submitted by F. P. Dwyer and J. W. Hogarth Checked by Richard N. RhodaI 

Caution. The same precautions mentioned in synthesis 59 should be observed. 

ampoule of osmium(VIII) oxide (0.004 mol) is broken into a 100-ml. Erlenmeyer flask (synthesis 59). Thirty milliliters of 12 M hydrochloric acid (0.36 mol) and 10 g. of either iron(II) chloride 6-hydrate (0.043 mol) or iron(II) chloride 4-hydrate (0.050 mol) are added. The flask is stoppered loosely and heated on a water bath with occasional shaking for 2 hours, whereupon the deep green color of the solution changes to orange-red. The solution is decanted from the broken glass into a 125-ml. beaker, and the flask is rinsed with 10 ml. of 12 M hydrochloric acid. Ten milliliters of 20% ammonium chloride solution (0.04 mol) is added, and the mixture is cooled with ice. The solid which forms is washed by decantation with 80% ethanol, transferred to a sintered-glass filter, and washed on the filter with absolute ethanol until free from chloride ion. It is then dried at 120°. The yield is 1.57 to 1.63 g. (91 to 94%). Anal. Calcd. for (NH4)z[OsC1 ] Os, 43.35. Found Os, 43.4. 

Ammonium hexachloroosmate(IV) crystallizes as deep red cubes and octahedra. It dissolves sparingly in cold water to give a greenish-yellow solution. 

---

Potassium hexacyanodinickelate-(I), synthesis 57 Ammonium hexabromoosmate-(IV), synthesis 59 Ammonium hexachloroosmate-(IV), synthesis 60... 

Carbonylchlorohydridotris(triphenylphosphine)osmium(II) was originally obtained by reacting ammonium hexachloroosmate(IV) and triphenylphosphine in a high-boiling alcoholic solvent17 and subsequently correctly formulated as a hydridocarbonyl com-plex.4,5,18 Optimum conditions reported for the synthesis involved a reaction time of 4.5 hours with temperature up to 190° and employed 2-(2-methoxyethoxy)ethanol-water mixture as solvent.18... 

Tetrahydridotris(triphenylphosphine)osmium(IV) has been prepared by reaction of sodium hexachloroosmate(IV) or ammonium... 

---