Synthesis and structural characterizations of four polyoxometalate compounds consisting of transition metals or alkaline cations as the bridging units

Four new polyoxometalate compounds, namely [Cu-2(pyrazine)(4)][Cu(pyrazine)(2)][PMo12O40] center dot 2H(2)O (1), {[K(H2O)(2)](4)H8PW12O44}F center dot 8H(2)O (2), H-9[K2KMo36O112(H2O)(34)] center dot 35H(2)O (3), and H3Na3[V10O28] center dot 15H(2)O (4), were prepared and characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. Single crystal X-ray diffraction analysis results reveal that, in compound 1, Keggin anion of [PMoO12O40](3) is enchased in the bowl-like Cu(I) -pyrazine intervals via weak interactions between terminal oxygen atoms and cations of Cu(I). For compound 2, a three-dimensional architecture with pores of 7.70 x 7.70 angstrom is constructed from the anions of [PW12O44](11) cross-linked via corner-sharing alkali cations of K+. The [Mo36O112(H2O)(16)](12) units of compound 3 are linked to form one wave-like chain via cations of K+. Whereas, in compound 4, anions of [V10O28](3) are linked via NaO6 octahedra to form two-dimensional layer structure. On the basis of this two-dimensional layer, a three-dimensional architecture is further formed via hydrogen bonds involving edge-shared NaO6 double octahedron. (C) 2009 Elsevier B. V. All rights reserved.