Synthesis and Structural Characterization of ... - Jacobs University

Chapter 5
Unpublished Results
Anderson-Evans type molybdotellurate(VI) has been reported by Bo et al. The same research
group also reported the cerium derivative one. 6
A series of lanthanide polyoxomolybdates
was synthesized before by the Krebs group by reaction of lanthanide cations with the
Anderson-Evans type anion [TeMo 6 O 24 ] 6– . 7
On the other hand, we recently reported two tungstotellurate(IV) anions [H 2 Te 4 W 20 O 80 ] 22−
and [NaTeW 15 O 54 ] 13− . 8 2−
The two polyanions were synthesized by the reaction of WO 4 and
Te 4+ in aqueous medium (pH 7.5). The polyanion [H 2 Te 4 W 20 O 80 ] 22− comprises two
{HTe 2 W 10 O 40 } fragments, connected through Te−O−W -oxo bridges, and each containing a
pair of face-shared WO 6 octahedra. The polyanion [NaTeW 15 O 54 ] 13−
is composed of a
triangular assembly of 15 edge- and corner-shared WO 6 octahedra, surrounding a trigonalpyramidal
tellurium(IV) center located in the central cavity and a capping sodium ion.
The complete lack of molybdotellurates(IV) as such [H 2 Te 4 W 20 O 80 ] 22− and
[NaTeW 15 O 54 ] 13− analogues provides an impetus to try to prepare such species. Herein we
report on a novel chiral molybdotellurate(IV) structure.
5.A.2.2. Synthesis
Na 34 [H 2 Te 24 Mo 44 O 198 ]·84H 2 O (Na-28)
A sample of 5.0 g of Na 2 MoO 4·2H 2 O (20.7 mmol) was dissolved in 20 mL H 2 O, followed by
dropwise addition of a solution of 0.66 g of TeO 2 (4.1 mmol) in 2 mL concentrated HCl. Then
the pH was adjusted to 6.5 using 6M aqueous NaOH. The mixture was vigorously stirred at
room temperature for 1 hour, and then filtered. The filtrate was kept in an open vial for
crystallization at room temperature. Colorless crystals of Na-28 were obtained after three days
which were in turn filtered off and air-dried. Yield: 1.18 g (53.6 %). IR for Na-28 in cm -1
(only between 400-1000 cm -1 ): 925(m), 867(s), 849(s), 808(m), 772(s), 705(m), 667(s),
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