Lanthanide-Containing 22-Tungsto-2-germanates [Ln(GeW<sub>11</sub>O<sub>39</sub>)<sub>2</sub>]<sup>13–</sup>: Synthesis, Structure, and Magnetic Properties
Ali S. Mougharbel, Saurav Bhattacharya, Bassem S. Bassil, Amna Rubab, Jan van Leusen, Paul Kögerler, Jakub Wojciechowski, Ulrich Kortz
Abstract
We report on the synthesis and structural characterization of two series of lanthanide-containing 22-tungsto-2-germanates. The first series corresponds to a family of polyanions with the formula [Ln(β2-GeW11O39)2]13– (LnIII = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Gd (6), Dy (7)), and the second series corresponds to a family with the formula [Ln(β2-GeW11O39)(α-GeW11O39)]13– (LnIII = Ho (8), Er (9), Tm (10)). All compounds were characterized in the solid state by single-crystal and powder XRD, IR, TGA, and SQUID magnetometry. The polyanions were synthesized in aqueous medium by direct reaction of the monolacunary [β2-GeW11O39]8– POM precursor with the corresponding lanthanide salts. The structure of the polyanions consists of an 8-coordinated lanthanide ion in a square-antiprismatic geometry, which is sandwiched either between two [β2-GeW11O39]8– units for 1–7 or between a [β2-GeW11O39]8– and a [α-GeW11O39]8– unit for 8–10. Furthermore, the effect of the central paramagnetic lanthanide ion on the magnetic behavior of the polyanions was investigated, with the erbium-derivative [Er(β2-GeW11O39)(α-GeW11O39)]13– (9) showing single-molecule magnet (SMM) behavior.