Experimental Section - New Synthetic Routes to Polyoxometalate Containing Ionic Liquids - page 99

5.3 Synthesis and Characterization
As the synthesis of one specific cluster-type e.g. the {SiW 11 M} mainly followed the same
synthetic route with (I) the synthesis of the lacunary cluster and (II) the incorporation of
a 3d-heteroelement, are the synthetic instructions combined in the following section
where appropriate.
5.3.1 Monolacunary Keggin-type Clusters
5.3.1.1 K 8 [ D -SiW 11 O 39 ] ڄ 13(H 2 O)
Sodium metasilicate 11 g (50 mmol) was dissolved at room temperature in 100 ml of
distilled water (solution A). In a 1-l beaker 182 g (0.55 mol) of sodium tungstate was
dissolved in 300 ml of boiling distilled water (solution B). Under vigorous stirring a
solution of 4M HCI (165 ml) was added drop wise to the boiling solution B, in ca. 30 min.
The local precipitate of tungstic acid, which at first formed with the HCl, was dissolved
completely. Solution A was then added, followed by quick addition of further 50 ml of
4M HCI. The pH reading showed a pH of 4.95. The solution was kept boiling for 1 h.
After cooling to room temperature, potassium chloride (150 g) was added to the
solution and stirred shortly. The white solid product was collected by filtration, washed
with two 50-ml portions of a KCI solution (1M) followed by two 30 ml portions of cold
water. The white solid obtained was recrystallized from water and the white crystalline
product dried in the exsiccator under vacuum for 5 days.
Yield: 109.4 g (34.0 mmol, 67.9% based on Si)
IR (characteristic bands in cm -1 ): 3420 (s), 2369 (w), 1618 (m), 1120 (w), 997 (m), 961 (s),
893 (s), 797 (s), 727 (s), 538 (m), 511 (m), 474 (m)