Synthesis and Structural Characterization of ... - Jacobs University

Chapter 3
Unpublished Results
bond lengths within the SbW 9 units are similar to those of [B-α-SbW 9 O 33 ] 9− anion. This
Sb 2 W 22 polyanion has a special feature, WO 6 octahedra with none or with three terminal
oxygen ligand atoms, in addition to the usual WO 6 octahedra with one or two terminal oxygen
ligand atoms. Another unusual feature in Sb 2 W 22 anion is the presence of terminal hydroxyl
groups. 5
Figure 3.26. Polyhedral (left) and ball-and-stick (right) representations of
[Sb 2 W 22 O 74 (OH) 2 ] 12− polyanion precursor (Sb 2 W 22 ). The color code is as follows: WO 6
octahedra (red) and rotated WO 6 octahedra (yellow), W (black), Sb (green), O (red).
It is noteworthy that Sb 2 W 22 polyanion was synthesized by reaction of the sodium salt of [Bα-SbW
9 O 33 ] 9− and WO 4 2− anions in water (pH 4 – 5). Addition of d-transition metal salts to
the aqueous solution of Sb 2 W 22 at pH 6 – 7 forms [M 2 (H 2 O) 6 Sb 2 W 20 O 70 ] (14−2n) (M 2 Sb 2 W 20 )
anions, M n+
= Fe 3+ , Co 2+ , Mn 2+ , Ni 2+ ). Exchange reactions lead these anions, the two
relatively weakly binding fac-WO 2 OH groups are substituted by two M n+ (H 2 O) 3 groups. 5
Since then, more metal ions derivatives of the Sb 2 W 20 unit have been synthesized and
reported. 6
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