Potassium Oxohexacarbonatotetraberyllates

Pure beryllium hydroxide, freshly prepared from 12 g. (0.06 mol) of beryllium nitrate 4-hydrate, is dissolved by 

The clear solution is placed in a glass-stoppered Erlen-meyer flask, and to it ethanol is added gradually and with frequent shaking until a heavy oily liquid separates. Por-tionwise addition of ethanol and agitation of the flask are continued until no further increase in the volume of the heavy layer is apparent or precipitation of potassium hydrogen carbonate begins. 

The heavy oily liquid is separated from the rest of the solution and is placed in another glass-stoppered flask. Water is added dropwise to the oily emulsion until it becomes clear. To this solution is added a volume of ethanol equal to approximately one-third the volume of the solution itself. After the mixture has been shaken and allowed to stand for a few minutes, two immiscible phases again result. The heavy oily liquid is again drawn off, and further extractions with water and with ethanol, respectively, are made (about 10 times ) until the dropwise addition of water causes a white flocculent precipitate to form. After the solution has stood several minutes, it is filtered through dry fine-textured filter paper (S S 589 or Whatman 42) and placed in a desiccator. 

After several days the potassium salt crystallizes from the syrupy solution as large transparent rhombohedra. The crystals are filtered by suction and quickly dried between folds of filter paper. After the crystals have been powdered and dried to constant weight over P4O10 the composition corresponds to that of the anhydrous salt, K6[Be40(C0,)d. Anal Calcd. for K,[Be40(C03)6] K, 36.28 Be, 5.57 CO2, 40.82. Found K, 36.46 Be, 5.51 CO2, 41.06. By checker K, 36.17 Be, 5.50. 

Hexaamminecobalt(III) carbonatoberyllates are generally insoluble in water, but complete precipitation of beryllium is obtained only in procedures A-1 and A-3. Although potassium oxohexacarbonatotetraberyllate dissolves in water to form a clear solution, a white flocculent precipitate separates after a few minutes, indicating that the complex carbonate anion must be unstable in aqueous solution. 

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Anhydrous potassium oxohexacarbonatotetraberyllate is thermally stable up to a temperature of 100° the hexa-amminecobalt(III) salts decompose at temperatures above 50°. 

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