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 [alpha-GeW11O39](8-), [alpha-SiW11O39](8-), and [alpha-SiMo12O40](4-) and the Wells-Dawson-type [alpha-P2W18O62](6-) polyanions in an aqueous, acidic medium resulted in plenary polyoxometalate-based materials K2Na[Ru3O(OOCCH3)(6)(H2O)(3)][alpha-GeW12O40] center dot 10H(2)O (1), K-3[Ru3O(OOCCH3)(6)(H2O)(3)][alpha-SiW12O40] center dot 18H(2)O (2), K-3[Ru3O(OOCCH3)(6)(H2O)(3)][alpha-SiMo12O40] center dot 7H(2)O (3), and K2Na[Ru3O(OOCCH3)(6)(H2O)(3)](3)[alpha-P2W18O62] center dot 26H(2)O (4), respectively. All four materials, 1-4, crystallize as sodium and/or potassium salts in the monoclinic space group P2(1)/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.