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[Nd2(H2O)10(α2-P2W17O61)]·11H2O (1), (H3O)[Nd3(H2O)17(α2-P2W17O61)]·6.75H2O (2), (H2bpy)2[Nd2(H2O)9 (α2-P2W17O61)]·4.5H2O (3), (H2bpy)2[La2(H2O)9(α2-P2W17O61)]·4.5H2O (4), and (H2bpy)2[Eu2(H2O)9(α2-P2W17O61)]·5H2O
(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(α2-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(α2-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(α2-P2W17O61)]n7n- linked by Ln3+ ions.
Compounds 2−5 represent the first extended structures formed by lacunary Wells−Dawson anions and trivalent
lanthanide ions. The influence of the Ln3+/[α2-P2W17O61]10- ratio on the syntheses of these five compounds has
been studied. Furthermore, the fluorescent activity of compound 5 is reported.