Press to Success: Gd 5 FW 3 O 16 —The First Gadolinium(III) Fluoride Oxidotungstate(VI)

The gadolinium(III) fluoride oxidotungstate(VI), with the formula Gd₅FW₃O₁₆, represents the first published fluoride-derivative of a rare-earth metal oxidotungstate. It is synthesized by a mixture of GdF₃, Gd₂O₃, and WO₃ at 800 &#176;C and a pressure of 2 GPa with the help of a belt press. The title compound crystallizes in the monoclinic space group <i>P</i>2₁/<i>c</i> (no. 14) with four formula units per unit cell and the following lattice parameters: <i>a</i> = 539.29 (4), <i>b</i> = 1556.41 (12), <i>c</i> = 1522.66 (11) pm, and <i>&#946;</i> = 93.452 (4). The crystal structure comprises five crystallographically distinguishable Gd³⁺ cations, which are surrounded by either oxide and fluoride anions (Gd1&#8722;3) or by oxide anions only (Gd4, Gd5), with coordination numbers ranging between seven and nine. The fluoride anions are trigonal non-planar coordinated by three Gd³⁺ cations (Gd1&#8722;3). The distorted [WO₆]^6&#8722; octahedra in this structure form isolates edge- and vertex-connected entities of the compositions [W₂O₁₀]^8&#8722; and [W₂O₁₁]^10&#8722;, respectively. According to the presented units, a structured formula can be written as Gd₄[FGd₃]₂[W₂O₁₀][W₂O₁₁]₂. The single-crystal Raman spectrum reveals the typical symmetric stretching vibration mode of octahedral oxidotungstate(VI) units at about 871 cm^&#8722;1.

Abstract licence: CC BY

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