Large Cation−Anion Materials Based on Trinuclear Ruthenium(III) Salts of Keggin and Wells-Dawson Anions Having Water-Filled Channels

Reaction of the trinuclear ruthenium(III) cation [Ru3O(OOCCH3)6(CH3OH)3]+ with the Keggin-type [α-GeW11O39]8−, [α-SiW11O39]8−, and [α-SiMo12O40]4− and the Wells−Dawson-type [α-P2W18O62]6− polyanions in an aqueous, acidic medium resulted in plenary polyoxometalate-based materials K2Na[Ru3O(OOCCH3)6(H2O)3][α-GeW12O40]·10H2O (1), K3[Ru3O(OOCCH3)6(H2O)3][α-SiW12O40]·18H2O (2), K3[Ru3O(OOCCH3)6(H2O)3][α-SiMo12O40]·7H2O (3), and K2Na[Ru3O(OOCCH3)6(H2O)3]3[α-P2W18O62]·26H2O (4), respectively. All four materials, 1−4, crystallize as sodium and/or potassium salts in the monoclinic space group P21/n. Compounds 1−4 were characterized by IR, thermogravimetric analysis, and single-crystal/powder X-ray diffraction (XRD). The isolated solid-state frameworks, composed of cocrystallized trinuclear ruthenium cations and polyanions, exhibit nanosized voids filled with crystal waters. These water molecules can be removed reversibly upon heating under a vacuum, and powder XRD measurements demonstrated that the crystallinity of the compound was preserved. Sorption studies on ethanol and methanol were also performed.