Synthesis and characterization of multinuclear manganese-containing tungstosilicates

The five manganese-containing, Keggin-based tungstosilicates [MnII3(OH)3(H2O)3(A-α-SiW9O34)]7– (1), [MnIII3(OH)3(H2O)3(A-α-SiW9O34)]4– (2), [MnIII3(OH)3(H2O)3(A-β-SiW9O34)]4– (3), [MnIII3MnIVO3(CH3COO)3(A-α-SiW9O34)]6– (4), and [MnIII3MnIVO3(CH3COO)3(A-β-SiW9O34)]6– (5) were synthesized in aqueous medium by interaction of [A-α-SiW9O34]10– or [A-β-SiW9O34H]9– with either MnCl2 (1) or [MnIII8MnIV4O12(CH3COO)16(H2O)4] (2–5) under carefully adjusted reaction conditions. The obtained salts of these polyanions were analyzed in the solid state by single-crystal X-ray diffraction, IR spectroscopy, and thermogravimetric analysis. The salts of polyanions 1, 2, and 4 were further characterized in the solid state by magnetic studies, as well as in solution by electrochemistry.