Synthesis and Structural Characterization of ... - Jacobs University

Chapter 2
Experimental
2.3.2 Synthesis of Na9[B‐α‐AsW9O33]·27H2O
11 g (0.056 mol) of As 2 O 3 were added to a hot solution of 330 g (1.0 mol) Na 2 WO 4·2H 2 O in
350 ml water. After the addition of 83 ml 11M HCl with vigorous stirring over 2 min, the
solution was heated at 95° C for 10 min. The product was kept in a beaker to crystallize
overnight. The crystals obtained were filtered off and air dried. 5
2.3.3 Synthesis of Na9[B‐α‐SbW9O33]·27H2O
A solution of 1.96 g (6.72 mmol) of Sb 2 O 3 in 10 mL concentrated HCl was added dropwise to
a hot solution of 40 g (121 mmol) of Na 2 WO 4·2H 2 O in 80 ml water. The mixture was
refluxed for 1 h and then kept to crystalize. After evaporation of one-third of the solution
volume, the crystals were formed and then filtered off and air dried. 6
2.3.4 Synthesis of Na12[Sb2W22O74(OH)2]
10 g (3.49 mmol) of Na 9 [B-α-SbW 9 O 33 ]·27H 2 O and 2.3 g (6.99 mmol) of Na 2 WO 4·2H 2 O
were dissolved in 10 mL water with gently heated. After the addition of ~ 23.5 mL of 1M
HC1 dropwise to adjust the pH to 4 – 5, the mixture was evaporated to one-third of its volume.
After cooling, the crystals were formed which were filtered off and air dried. 6
2.3.5 Synthesis of K8[β2‐GeW11O39]·14H2O
5.4 g (0.052 mol) of GeO 2 were dissolved in 100 mL water (solution A). Then, 182 g (0.552
mol) of Na 2 WO 4·2H 2 O were dissolved in 300 mL of water in a separate beaker (solution B).
After addition of 165 mL of 4M HCl to the solution B with vigorous stirring in small portions
over 15 min, solution A was poured into the tungstate solution (solution B) and the pH
adjusted to 5.2 – 5.8 by addition of 4 M HCl solution (~ 40 mL). This pH was kept at this
value for 100 min. by addition of the HCl solution. Then, 90 g of solid KCl were added with
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