Structure and Properties of New Gallium‐containing Polyoxotungstates with Hexanuclear and Tetranuclear Cores

Abstract

AbstractA series of new gallium‐containing silicotungstates was obtained from the one step reaction of the lacunary Na10[α‐SiW9O34]·15H2O Keggin‐type building block (SiW9) with gallium nitrate in aqueous solution. The sandwich‐type polyoxotungstate [Ga6(H2O)x{α‐SiW9O34(OH)y}2]n– (1) crystallizes first as a mixture of two similar polyoxometalates (1a and 1b), while [Ga4(H2O)2{α‐SiW10O38}2]12– (2) is generated from the mother liquor in a second step. Both newly obtained polyoxometalates with tetra‐ and hexanuclear gallium cores were structurally characterized with a wide range of methods encompassing single crystal and powder X‐ray diffraction techniques, FT‐IR spectroscopy, and thermal analysis. The solution stability of both dimeric POMs K10[Ga6(H2O)3{α‐SiW9O35(OH)2}2]·35.5H2O (1a) and K12[Ga4(H2O)2{α‐SiW10O38}2]·30H2O (2) was investigated with 183W NMR and HR ESI mass spectrometry, and the electrochemical properties of both compounds were determined by cyclic voltammetry.