Preparation and characterization of two new isomorphous heteropoly oxofluorotungstate anions [CoW17O56F6NaH4]9- and [FeW17O56F6NaH4]8-

The ammonium salts of [CoW 17 H 4 NaO 56 F 6 ] 9− and [FeW 17 H 4 NaO 56 F 6 ] 8− have been isolated in crystalline form. X-ray powder patterns of the two compounds are identical. The crystals of (NH 4 ) 8 (FeW 17 O 56 F 6 NaH 4 )•8H 2 O belong to the space group Pnma