Synthesis and Structural Characterization of ... - Jacobs University

Chapter 2
Experimental
2.3.8 Synthesis of Na10[A‐‐GeW9O34]·4H2O
18 g (0.55 mol) of Na 2 WO 4·2H 2 O and 5.23 g (50 mmol) of GeO 2 were dissolved in 200 ml of
hot water (80-100° C) in an 1L beaker. After addition of 130 ml of 6M HCl to this solution
with vigorous stirring over∼30 min, the solution was boiled until the volume was ∼300 ml
and cooled down to room temperature and then filtered over a fine frit to remove the
unreacted species. A solution of 50 g of anhydrous Na 2 CO 3 in 150 ml of water was slowly
added to the first solution with gentle stirring. A precipitate was slowly formed (overnight).
This precipitate was collected by filtering using a sintered glass filter. For purification the
precipitate was stirred in 1L of 4M NaCl solution and filtered again, and washed successively
with two 100-ml portions of ethanol and 100 ml of diethyl ether and then dried at room
temperature. 9
2.3.9 Synthesis of K8[BW11O39H]·13H2O
A 300 g sample of Na 2 WO 4·2H 2 O and a 20 g sample of H 3 BO 3 were dissolved in 500 mL of
boiling water. After addition of ∼ 190 mL of 6 M HCl over 20 minutes with vigorous stirring
in order to dissolve the local precipitate of tungstic acid until the pH was 6, the solution was
kept boiling for 1 h and after cooling to room temperature it was kept 24 h at 4 °C. The
precipitate was removed by filtration, and then the potassium salt was precipitated from the
solution by addition of KCl (∼100 g). The crude potassium salt was dissolved in 1 L of water,
the insoluble part eliminated, and the potassium salt precipitated again by addition of KCl
(∼100 g). 10
2.3.10 Synthesis of K6[α‐P2W18O62] ·20H2O
A sample of Na 2 WO 4·2H 2 O (300 g; 0.91 mol) dissolved in 350 mL water was acidified by
fractional addition of 4M HCl (250 mL) under vigorous stirring. After slowly addition of 250
mL 4M H 3 PO 4 to the limpid solution, the formed pale yellow solution was refluxed for at
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