Synthesis and Structural Characterization of ... - Jacobs University

Chapter 5
Published Results
5.A.1.2. Synthesis
Na 22 [H 2 Te 4 W 20 O 80 ]·64H 2 O (Na-26)
A sample of 10.00 g of Na 2 WO 4·2H 2 O (30.3 mmol) was dissolved in 20 mL 1M NaCl,
followed by dropwise addition of a solution of 1.07 g of TeO 2 (6.7 mmol) in 2.5 mL
concentrated HCl. Then the pH was adjusted to 7.5 using 4M aqueous HCl, and a white sticky
precipitate was formed. The mixture was vigorously stirred at room temperature for 1 h, and
then the precipitate was filtered off and discarded. The filtrate was kept in an open vial for
crystallization at room temperature. After a day, colorless crystals of paradodecatungstate
([H 2 W 12 O 42 ] 10- ) started to appear and were filtered off successively and discarded until
needle-shaped, colorless crystals of Na-26 were formed (after ~1 week). These crystals were
in turn filtered off and air-dried. Yield: 0.77 g (7.1 %). IR for Na-26 in cm -1 (only between
400-1000 cm -1 ): 925(m), 873(m), 848(w), 801(sh), 738(s), 692(m), 619(w), 475(w), 421(w),
see Figure 5.1.
Figure 5.1. IR spectrum of Na 22 [H 2 Te 4 W 20 O 80 ]·64H 2 O (Na-26).
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