A Giant 3d-4f Polyoxometalate Super-Tetrahedron with High Proton Conductivity.

The assembly of gigantic heterometallic metal clusters remains a great challenge for synthetic chemistry. Herein, based on the slow release strategy of lanthanide ions and in situ formation of lacunary polyoxometalates, two giant 3d-4f polyoxometalate inorganic clusters [LaNi ₁₂ W ₃₅ Sb ₃ P ₃ O ₁₃₉ (OH) ₆ ] ^23- (LaNi ₁₂ ) and [La ₁₀ Ni ₄₈ W ₁₄₀ Sb ₁₆ P ₁₂ O ₅₆₈ (OH) ₂₄ (H ₂ O) ₂₀ ] ^86- (La ₁₀ Ni ₄₈ ) are obtained. The nanoscopic inorganic cluster La ₁₀ Ni ₄₈ possesses a super tetrahedron structure, which can be viewed as assembly from four LaNi ₁₂ molecules encapsulating a central [La ₆ (SbO ₃ ) ₄ (H ₂ O) ₂₀ ] ⁶⁺ octahedron core. This giant aesthetic La ₁₀ Ni ₄₈ tetrahedron containing 214 metal ions is the largest 3d-4f cluster reported thus far in polyoxometalate system. More interestingly, the LaNi ₁₂ and La ₁₀ Ni ₄₈ display high stability in solution and La ₁₀ Ni ₄₈ displays excellent proton conductivity.
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