Dinuclear oxofluorometallates as a new structural type of d0 transition metal oxofluoride compound

• Published in: Acta crystallographica. Section B, Structural science Vol. 68; no. 6; pp. 602 - 609
• Main Authors: Udovenko, Anatoly A., Laptash, Natalia M.
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01-12-2012; Blackwell Publishing Ltd
• Subjects: Atoms & subatomic particles; Bridging; bridging fluorine atoms; Corners; Crystal structure; Crystallography; Diffraction; Dimers; dinuclear oxofluorometallates; Fluorides; Fluorine; merohedral twins; Metals; Transition metals; Unit cell; vibrational spectra
• ISSN: 0108-7681; 2052-5192; 1600-5740; 2052-5206
• DOI: 10.1107/S0108768112042577

Five isomorphous d0 transition metal oxofluoride compounds A3[M2OxF11 − x]·(AF)0.333 (A = K, Rb, NH4; M = Nb, Mo, W; x = 2, 4) have been synthesized from acid fluoride solutions, and their crystal structures have been determined by single‐crystal X‐ray diffraction. The basic structural building units are dinuclear M2X11 (dimers) formed from NbOF5 or Mo(W)O2F4 octahedra connected by the fluorine bridging atom. In the Nb2O2F9 dimer, the O atoms occupy apical corners. In the M2O4F7 (M = Mo, W) dimers two O atoms are also apically placed, whereas the other two O atoms are statistically disordered in equatorial planes. The arrangement of dimers is so that the hexagonal tunnels containing `free' fluoride ions are formed. During the irradiation process the orthorhombic structure of K3Nb2O2F9·(KF)0.333 transforms into a pseudo‐trigonal one with a = 23.15 Å, which is the [101] diagonal of the orthorhombic unit cell. The other four trigonal crystals are merohedral twins.