A Dimeric Fe(III)-Substituted α-Keggin Tungstogermanate: {[α-GeFe2W10O38(OH)]2}14−

Abstract

The dimeric Fe(III)-substituted α-Keggin tungstogermanate {[α-GeFe2W10O38(OH)]2}14− (1) was synthesized by reaction of iron(III) with [A-α-GeW9O34]10− in neutral medium and characterized by elemental analysis, IR, UV-Vis, TG-DSC and electrochemistry. An X-ray single-crystal analysis was carried out on K14[α-GeFe2W10O38(OH)]2 ·34H2O, which crystallizes in the monoclinic system, space group P21/c, with a = 20.510(3) A, b = 15.565 (2) A, c = 17.998(2) A, β = 114.672(2)° and Z = 2. The polyanion 1 consists of two [α-GeFe2W10O38(OH)] Keggin moieties linked via two bridging hydroxo groups, leading to a planar Fe4O2(OH)2 cluster. The two half-units are related by an insertion center. The locating of the hydroxo groups is done by the bond valence sum calculations. The TG-DSC results show that the polyanion 1 is stable below 520 °C.