Iron(II) and copper(II) paratungstates B: a single-crystal X-ray diffraction study.

Paratungstate B is a common isopolytungstate (IPOT) built of the [W12O40(OH)2]10- anion and exhibits a cluster-like construction of 12 W-centred distorted octahedra. Due to a high surface charge density, the paratungstate anion acts as a multidentate ligand forming high-dimensional extended structures, which exhibit unique catalytic and magnetic properties. Two new paradodecatungstate B compounds decorated by iron(II) or copper(II), namely Na5Fe2.5[W12O40(OH)2]·36H2O (Na5Fe2.5paraB) and Na4Cu3[W12O40(OH)2]·28H2O (Na4Cu3paraB), have been synthesized by a convenient aqueous solution method, and structurally characterized by single-crystal and powder X-ray diffraction, IR spectroscopy, elemental analysis and thermogravimetric analysis. Both compounds crystallize in the triclinic P-1 space group. In both compounds, the [W12O40(OH)2]10- polyanion acts as a multidentate ligand that links transition-metal and sodium cations, forming a three-dimensional framework.