The fluorination of scheelite with ammonium bifluoride

The interaction of scheelite with ammonium bifluoride was studied. It was shown that sheelite reacts with NH 4 HF 2 at room temperature, in contrast with tungstic oxide and other tungsten compounds. Two complexes are formed (NH 4 ) 3 WO 3 F 3 and the previously unknown (NH 4 ) 2 WO 3 F 2 . The compounds obtained were fluorinated to (NH 4 ) 3 WO 2 F 5 (endothermic peaks at 170 o and 90 o C, respectively). Cubic monocrystals of (NH 4 ) 3 WO 2 F 5 were obtained.