Sodium hexafluorouranate

Sodium Hexafluorouranate(V) Uranium pentafluoride (2.00 g) and dried NaF (0.25 g) are combined in a 250-mL flask in a drybox. The flask is then attached to a vacuum line, and approximately 150 mL of dry acetonitrile is vacuum transferred into the flask. (The acetonitrile can be dried by distillation from P4O10 or CaH2.) The mixture is allowed to warm to room temperature. With stirring, the NaF gradually dissolves over a period of 12 hours. The solvent is removed in vacuo, quantitatively yielding NaUF6 in the rhombohedral form (X-ray powder diffraction). The potassium salt is prepared similarly. 

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