Synthesis and Structural Characterization of ... - Jacobs University

Chapter 5
Published Results
Figure 5.3. Polyhedral representation of the [HTe 2 W 10 O 40 ] 11− half-unit of 26. The color code
is as follows: WO 6 octahedra (green, light blue, pink, red); Te (blue); O (red). The WO 6
octahedra were colored differently for clarity. See also text and Figure 5.4. The eight Te–
O(W) bond distances range from 1.853(6) to 2.332(6) Å.
The decatungstate {W 10 } unit can be considered as an assembly of four types of ‘building
blocks’ (see Figure 5.4):
- One tritungstate {W 3 } fragment (green in Figure 5.4) made of three edge-shared
[WO 6 ] octahedra connected via a μ 3 -oxo bridge. This fragment can be viewed as a
single ‘triad’ of the well-known Keggin and Wells-Dawson structures. 1a
- One ditungstate {W 2 } subunit (light blue in Figure 5.4) made of two face-shared
[WO 6 ] octahedra connected via three μ 2 -oxo bridges. This feature is very rare in POM
chemistry. 1a Face-shared W VI O 6 octahedra result in large coulombic repulsion between
the highly positively charged metal centers. In 26, the separation between the faceshared
tungsten atoms (W1···W2) is 3.060(7) Å, shorter than the separations in
corner-shared or edge-shared octahedra (approximately 3.7 and 3.4 Å, respectively).
In 1968 Dexter and Silverton presented the first example of a polyanion containing
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