Synthesis, Crystal Structure And Characterization Of New Tungstosilicate Aggregates Based On Lacunary Keggin Fragments

In this paper,we synthesized five new tungstosilicates clusters by using differert lacunary Keggin species in different pH values,temperatures under ambient conditions. Compound 1 and 2 are pure tungstosilicate cluster,the others are transition-metal tungstosilicate clusters All compound characterized by elemental analyses,IR,TG,and single-crystal X-ray diffraction..In addition,for compound 3,4 and 5,we do research on their character of cyclic voltammetry.The factors influencing the structures of these compounds have also been studied.Five new tungstosilicates compounds have been prepared by using lacunary Keggin silicotungstates as building blocks:(1)K₄Na₁₁Li₅[Si₃W₂₆O₉₄]·～21H₂O(2)K₅Na₁₁[Si₂W₁₉O₆₉(H₂O)]·～22H₂O(3)K₆Na₂Ni₂[Ni₄(H₂O)₂(SiW₉O₃₄)₂]·30H₂O(4)K₆Na₂Co₂[Co₄(H₂O)₂(SiW₉O₃₄)2]·32H₂O(5)K₁₂Na₂[Fe₂SiW₁₀O₃₈(OH)]₂·32H₂OFrom these compounds,we can conclude:we can obtain new POM-based polynuclear (include pure tungstosilicate cluster and transition-metal tungstosilicate clusters)aggregates by the control of pH,reaction temperature and time,which provide various intermediate polyoxoanion building blocks and are helpful for the isolation of new large clusters.Based on the carefully analysis,the possible assembly routes of these compounds were speculated.