Aquabis ethylenediamine hydroxocobalt III Dithionate

The pure sample is obtained by reprecipitation. Ten grams of the crude product is dissolved in 60.0 ml. of ice-cold 0.5 N hydrochloric acid with cooling in an ice bath. Then 15 ml. of ice-cold 2 N sodium hydroxide is added to the filtered solution with stirring and cooling, and m-aquabis(ethylenediamine)-hydroxocobalt(III) dithionate is isolated as above. Yield is 8.4 g. (84%). The visible absorption spectrum in acidic or basic solution of the sample reprecipitated twice in this manner does not change after the second precipitation. Anal. Found Co, 15.74 C, 12.72  

The dithionate salt is almost insoluble in water. It dissolves in acid or base with formation of the corresponding cis-diaqua and cw-dihydroxo species, respectively.11 The absorption spectrum in 

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Besides (carbonato)bis(ethylenediamine)cobalt(III) chloride and the corresponding bromide salt, the following complexes are described cis- and frara -dichlorobis(ethylenediamine)cobalt(III) chloride, cts-aquachlorobis(ethylenediamine)cobalt(III) sulfate, cis-bis(ethylenediamine)dinitrocobalt(III) nitrite, m-aquabis-(ethylenediamine)hydroxocobalt(III) dithionate, and cis-diaqua-bis(ethylenediamine)cobalt(III) bromide. 

In the procedure given below, di-/a-hydroxo-bis[bis(ethylenediamine)cobalt-(III)] dithionate is obtained quantitatively from ds-[aquabis(ethylenediamine)-hydroxocobalt(III)] dithionate by refluxing in acetic anhydride. The ds-[aqua-bis(ethylenediamine)hydroxocobalt(III)] dithionate is obtained from carbo-natobis(ethylenediamine)cobalt(III) chloride. ... 

Crude ds-[aquabis(ethylenediamine)hydroxocobalt(III)] dithionate (40.0 g, 0.107 mole) is added to 400 mL of acetic anhydride. The suspension is refluxed for 3 hours. The crude di-/i-hydroxo-bis[bis(ethylenediamine)cobalt(III)] dithionate is isolated analogously to the chromium(III) complex as mentioned in Section 15-J. Yield is 34.0 g (89%) of a crude, almost pure product. 

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