Disorder in crystals of dioxofluorotungstates, (NH(4))(2)WO(2)F(4) and Rb(2)WO(2)F(4)

作者：Udovenko Anatoly A^*; Laptash Natalia M

来源：Acta Crystallographica Section B-Structural Science, 2008, 64(6): 645-651.

DOI：10.1107/S0108768108033053

Dioxotetrafluorotungstates (NH(4))(2)WO(2)F(4) [(I) at 297 K and (II) at 133 K] and Rb(2)WO(2)F(4) (III) were synthesized in a single-crystal form and their structures were determined by Xray diffraction. Two independent states of the cis-WO(2)F(4) octahedron are characteristic of static and dynamic disorder in structure (I). Dynamically disordered W2 is displaced from the symmetry axis producing four possible orientations of anion that permits O and F atoms to be identified in separate orientations owing to the inherent differences between W-O and W-F bonding. After the phase transition at lower temperature (201 K), (I) transforms into the twin structure (II) with complete O/F ordering. Structure (III) is characterized by full O/F static disorder without any phase transitions at lower temperature.

• 出版日期2008-12