Cyclic Tungstoselenites Based on {Se<sub>2</sub>W<sub>12</sub>} Units

The reaction of Na<sub>2</sub>WO<sub>4</sub> and SeO<sub>2</sub> under moderately acidic conditions yielded a novel 39-tungsto-6-selenite, [(Se<sub>2</sub>W<sub>12</sub>O<sub>46</sub>(WO­(H<sub>2</sub>O))<sub>3</sub>]<sup>24–</sup> (<b>1</b>), isolated as Na<sub>24</sub>[H<sub>6</sub>Se<sub>6</sub>W<sub>39</sub>O<sub>144</sub>]·74H<sub>2</sub>O. The macrocyclic polyanion consists of three {Se<sub>2</sub>W<sub>12</sub>} fragments connected via three <i>trans</i>-{WO­(H<sub>2</sub>O)}<sup>4+</sup> groups. The same {Se<sub>2</sub>W<sub>12</sub>} building block is present in the structure of [(Se<sub>2</sub>W<sub>12</sub>O<sub>46</sub>)<sub>2</sub>{Mn<sub>2</sub>Cl­(H<sub>2</sub>O)<sub>2</sub>}­{Mn­(H<sub>2</sub>O)<sub>2</sub>}<sub>2</sub>(SeO)<sub>2</sub>]<sup>13–</sup> (<b>2</b>), which was obtained from the same reagents in the presence of MnCl<sub>2</sub>. The compounds were characterized by single-crystal X-ray diffraction, <sup>77</sup>Se NMR, Fourier transform infrared, and Raman spectroscopy.