New polyoxometalate compounds built up of lacunary Wells-Dawson anions and trivalent lanthanide cations

Five new polyoxometalate compounds built on lacunary Wells-Dawson anions and trivalent lanthanide cations, KNa3(Nd-2(H2O)(10)(alpha(2)-P2W17O61)](.)11H(2)O (1), (H3O)[Nd-3(H2O)(17)(alpha(2)-P2W17O61)](.)6.75H(2)O (2), (H(2)bPY)(2)[Nd-2(H2O)9 (alpha(2)-P2W17O61)](.)4.5H(2)O (3), (H(2)bPY)(2)[La-2(H2O)(9)(alpha(2)-P2W17O61)](.)4.5H(2)O (4), and (H(2)bPY)(2)[Eu-2(H2O)(9)(alpha(2)-P2W17O61)](.)5H(2)O (5), have been synthesized and characterized by elemental analysis, IR, TG, and single-crystal X-ray diffraction. Compound 1 shows a bisupporting polyoxometalate cluster structure where two {Nd(H2O)(7)}(3+) fragments are supported on the polyoxometalate dimer {Nd(H2O)(3)(alpha(2)-P2W17O61)}(2)](14-); this represents the first bisupporting polyoxometalate compound based on a polyoxometalate dimer. Compound 2 displays a 1D chain structure built up of bisupporting polyoxoanions [{Nd(H2O)(7)}(2){Nd(H2O)(3)(alpha(2)-P2W17O61)}(2)](8-) and Nd3+ ions. Compounds 3-5 are isostructural and show a 2D structure constructed of 1D polyoxometalate chains of [Ln(H2O)(2)(alpha(2)-P2W17O61)](n)(7n-) linked by Ln(3+) ions. Compounds 2-5 represent the first extended structures formed by lacunary Wells-Dawson anions and trivalent lanthanide ions. The influence of the Ln(3+)/[alpha(2)-P2W17O61](10-) ratio on the syntheses of these five compounds has been studied. Furthermore, the fluorescent activity of compound 5 is reported.