Anderson-Type Polyoxotungstate with Central Ruthenium, [RuIVW6O24]8-: Synthesis, Structure, Redox Studies, and Electrochemical Water Oxidation Activity.

The reaction of Na2WO4·2H2O with [(benzene)RuCl2]2 at temperatures above 70 °C produced an Anderson-type ruthenotungstate, Na8[RuIVW6O24], together with (benzene)Ru-tungstates, [{(benzene)Ru}4W2O10] and Na6[{(benzene)Ru}2H2W8O30]. The first ruthenium-containing Anderson-type polyoxometalate was isolated by recrystallization and characterized using single-crystal X-ray diffraction (XRD), elemental analysis, powder XRD, infrared (IR) spectroscopy, thermogravimetry-differential thermal analysis (TG-DTA), X-ray absorption fine structure (XAFS), and cyclic voltammetry. Notably, Na8[RuIVW6O24] could only be synthesized using [(benzene)RuCl2]2; other ruthenium sources, such as RuCl3, Ru(DMSO)4Cl2, Ru(acac)3, and K2RuCl5(H2O), did not yield Na8[RuIVW6O24] under the same conditions. Cyclic voltammetry measurements revealed that the RuIV ions in Na8[RuIVW6O24] undergo a quasi-reversible one-electron redox process, RuIV/III. Furthermore, Na8[RuIVW6O24] demonstrates catalytic performance in water oxidation reactions, significantly outperforming the catalytic activity of Na6[{(benzene)Ru}2H2W8O30] and [{(benzene)Ru}4W2O10] complexes, highlighting its potential as an efficient catalyst for energy conversion processes.