Synergistic combination of multi-Zr^IV cations and lacunary keggin germanotungstates leading to a gigantic Zr₂₄-cluster- Substituted Polyoxometalate

Synergistic directing roles of six lacunary fragments resulted in an unprecedented Zr₂₄-cluster substituted poly(polyoxotungstate) Na ₁₀K₂₂[Zr₂₄O₂₂(OH) ₁₀(H₂O)₂(W₂O₁₀H) ₂(GeW₉O₃₄)₄(GeW₈O ₃₁)₂]·85H₂O (Na₁₀K ₂₂·1·85H₂O), which contains the largest [Zr₂₄O₂₂(OH)₁₀(H₂O)₂] (Zr₂₄) cluster in all the Zr-based poly(polyoxometalate)s to date. The most remarkable feature is that the centrosymmetric Zr₂₄-cluster- based hexamer contains two symmetry-related [Zr₁₂O ₁₁(OH)₅(H₂O)(W₂O₁₀H) (GeW₉O₃₄)₂(GeW₈O₃₁)] ^16- trimers via six μ₃-oxo bridges and was simultaneously trapped by three types of different segments of B-α-GeW₉O₃₄, B-α-GeW₈O ₃₁, 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 ₁₀K₂₂·1·85H₂O 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 Na₁₀K₂₂·1·85H₂O provide a sufficient driving force for the catalytic conversion from thioethers to sulfoxides/sulfones.