Synthesis and characterization of three new solid polyoxometalates based on Wells-Dawson-derived sandwich-type polyanions [Co4(H2O)2(P2W15O56)2]16−
摘要
Three polyoxometalate-based hybrid coordination materials, [Co8(H2O)34(pz)2{Co4(H2O)2P4W30O112}]·16H2O (compound 1), [H3O]4[Co6(H2O)22(pz)2{Co4(H2O)2P4W30O112}]·21H2O (compound 2), and [H3O]4[Co6(H2O)22{Co4(H2O)2P4W30O112}]·29H2O (compound 3) (pz=pyrazine), were built from the linkage of [Co4(H2O)2(P2W15O56)2]16− (abbreviated as {Co4P4W30}) polyanions and pz and/or cobalt(II) cations. Although compounds 1 and 2 consisted of the same components, their lamellar networks were quite different. The inorganic lamellar network in compound 3 was constructed by connecting {Co4P4W30} units with cobalt(II) cations. This work demonstrates that the coordination modes of {Co4P4W30} are very sensitive to synthesis conditions, while the ring-belt tetrametals are easily substituted by different transition metal cations under mild reaction conditions.