Synergistic Combination of Multi-ZrIV Cations and Lacunary Keggin Germanotungstates Leading to a Gigantic Zr24-Cluster-Substituted Polyoxometalate

Synergistic directing roles of six lacunary fragments resulted in an unprecedented Zr-24-cluster substituted poly(polyoxotungstate) Na10K22[Zr24O22(OH)(10)-(H2O)(2)(W2O10H)(2)(GeW9O34)(4)(GeW8O31)(2)]center dot 85H(2)O (Na10K22 center dot 1 center dot 85H(2)O), which contains the largest [Zr24O22(OH)(10)(H2O)(2)] (Zr-24) cluster in all the Zr-based poly(polyoxometalate)s to date. The most remarkable feature is that the centrosymmetric Zr-24-cluster-based hexamer contains two symmetry-related [Zr12O11(OH)(5)(H2O)(W2O10H)(GEW(9)O(34))(2)(GeW8O31)](16-) trimers via six mu(3)-oxo bridges and was simultaneously trapped by three types of different segments of B-alpha-GeW9O34, B-alpha-GeW8O31, and W2O10. The other interesting characteristic is that there are two pairs of intriguing triangular atom alignments: one is composed of the Zr(2,4,6,8,11) and W21 atoms and the other contains the Ge(1-3), Zr(3,5,7,9,10,12) and W26 atoms, and the Zr5 atom is inside the triangle; a linking mode is unobserved. The oxygenation reactions of thioethers by H2O2 were evaluated when Na(10)K22 center dot 1 center dot 85H(2)O served as a catalyst. Results show that it is an effective catalyst for oxygenation of thioethers by H2O2. The unique redox property of oxygen-enriched polyoxotungstate fragments and Lewis acidity of the Zr cluster imbedded in Na10K22 center dot 1 center dot 85H(2)O provide a sufficient driving force for the catalytic conversion from thioethers to sulfoxides/sulfones.