Synthesis and Structural Characterization of ... - Jacobs University

Chapter 4
Unpublished Results
4.5. Conclusions
We have synthesized two 16-iron(III)-containing phosphotungstates coordinated to four
lanthanide centers and composed of an unprecedented open-ring P 8 W 49 unit,
[Fe 16 O 2 (OH) 23 (H 2 O) 9 (P 8 W 49 O 189 )Ln 4 (H 2 O) 20 ] 11−
(Ln = Eu (24) and Gd (25)). They are
synthesized in simple, one-pot reactions of Ln(III) and Fe(III) salts with the large
superlacunary polyanion precursor P 8 W 48 and isolated as hydrated mixed potassium-lithiumsodium-lanthanide
salts KLiNa-24 and KLiNa-25. These salts have been studied in the solid
state by IR spectroscopy, single-crystal X-ray diffraction, TGA and elemental analysis. It is
apparent that the presence of lanthanide ions is a crucial parameter in the synthesis of 24 and
25. However, the mechanism cleavage of the wheel-shaped P 8 W 48 is still unclear. Attempts to
synthesize the open-ring Fe 16 P 8 W 49 in the absence of lanthanides ions are still underway
using different synthetic procedures. Furthermore, isolation the novel P 8 W 49 or P 8 W 48 * as
new precursors, starting from either the wheel-shaped P 8 W 48 or other phosphotungstate
precursors such as P 2 W 12 and P 4 W 24 will be the scope of further studies.
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