22-Isopolytungstate Fragment [H₂W₂₂O₇₄]¹⁴⁻Coordinated to Lanthanide Ions

Abstract

The novel polyanions [Ln(2)(H(2)O)(10)W(22)O(71)(OH)(2)](8-) (Ln = La (1), Ce (2), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), Yb (8), Lu (9), Y (10)) have been synthesized by reaction of WO(4)(2-) and lanthanide ions in acidic aqueous medium. The low symmetry (C(i)) polyanion family [Ln(2)(H(2)O)(10)W(22)O(71)(OH)(2)](8-) consists of the isopolyanion [H(2)W(22)O(74)](14-) and two {Ln(H(2)O)(5)}(3+) supporting units. The [H(2)W(22)O(74)](14-) cluster, which consists of two undecatungstate {W(11)} fragments, acts as a tridentate ligand to two Ln(3+) ions. Polyanions 1-10 are isostructural, and the coordination number of the lanthanide ions correlates with their sizes. All compounds have been fully characterized in the solid state by Fourier transform infrared spectroscopy, single-crystal X-ray diffraction, thermogravimetric analysis, and elemental analysis. Single-crystal X-ray diffraction analyses show that 1-10 crystallize as sodium salts in the triclinic space group P1.