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

Paratungstate B is a common isopolytungstate (IPOT) built of the [W(12)O(40)(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 Na(5)Fe(2.5)[W(12)O(40)(OH)(2)]·36H(2)O (Na(5)Fe(2.5)paraB) and Na(4)Cu(3)[W(12)O(40)(OH)(2)]·28H(2)O (Na(4)Cu(3)paraB), 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 [Image: see text] space group. In both compounds, the [W(12)O(40)(OH)(2)](10−) polyanion acts as a multidentate ligand that links transition-metal and sodium cations, forming a three-dimensional framework.