Acta Crystallographica Section B

Structural Science

Volume 68, Part 6 (December 2012)


research papers



Acta Cryst. (2012). B68, 602-609    [ doi:10.1107/S0108768112042577 ]

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

A. A. Udovenko and N. M. Laptash

Abstract: 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.

Keywords: dinuclear oxofluorometallates; vibrational spectra; bridging fluorine atoms; merohedral twins.


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Structure factor file (CIF format) (292.2 kbytes)
[ doi:10.1107/S0108768112042577/bp5045Isup2.hkl ]
Contains datablock I


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Structure factor file (CIF format) (170.6 kbytes)
[ doi:10.1107/S0108768112042577/bp5045IIsup3.hkl ]
Contains datablock II


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Structure factor file (CIF format) (211.3 kbytes)
[ doi:10.1107/S0108768112042577/bp5045IIIsup4.hkl ]
Contains datablock III


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Structure factor file (CIF format) (205.4 kbytes)
[ doi:10.1107/S0108768112042577/bp5045IVsup5.hkl ]
Contains datablock IV


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Structure factor file (CIF format) (159.4 kbytes)
[ doi:10.1107/S0108768112042577/bp5045Vsup6.hkl ]
Contains datablock V


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