Uranyl Cyanate, UO₂(CNO)₂

Uranyl Cyanate, UO₂(CNO)₂, separates as a golden-yellow powder when alcohol and excess of uranyl nitrate are added to a solution of potassium uranyl cyanate, K₂UO₂(CNO)₄. The cryoscopic behaviour of solutions of uranyl cyanate containing various proportions of potassium cyanate indicates that the double potassium uranyl salt is present in solutions containing an excess of potassium cyanate. The same complex, which may be formulated [UO₂(CNO)₄]K₂, is obtained as a voluminous yellow precipitate, possessing a greenish fluorescence, by adding a fresh alcoholic solution of potassium cyanate to a neutral solution of uranyl nitrate. It is very soluble in water, and, owing to hydrolysis, the solution responds to all the tests for uranium, but on keeping, an orange-yellow precipitate of composition [(UO₂)₂(CNO)₅]K is formed. If, however, an excess of potassium cyanate is present in the solution, a golden-yellow precipitate of composition [UO₂(CNO)₃]K separates.