Chapter 4 - Jacobs University

Chapter 3 The Wheel-Shaped Cu 20
3.5 Conclusion
We have synthesized a large, wheel-shaped, Cu 20 containing polyanion by direct reaction of Cu 2+
ions with [H 7 P 8 W 48 O 184 ] 33- . The polyanion 1 contains more paramagnetic 3d transition-metal
centers than any other polyoxotungstate reported to date. Furthermore, it is stable in solution, as
shown by 31 P NMR spectroscopy. Contrary to prior reports, we have shown that the wheelshaped
[H 7 P 8 W 48 O 184 ] 33- 1) actually does react with transition-metal ions in aqueous medium
using simple, one-pot procedures, 2) is to be considered as a superlacunary polyanion precursor,
3) acts as a template which allows the construction of large transition-metal-oxo clusters, and 4)
is probably also reactive towards many other electrophiles (e.g. rare earths and organotin
species). We consider [H 7 P 8 W 48 O 184 ] 33- as a ligand of choice in our search for paramagnetic
polyanions with high spin ground states. Currently we are investigating the magnetic, EPR, and
electrochemical properties of 1 and these results will be reported elsewhere. We are also
interested to see of derivatives of 1 incorporating other transition-metals besides Cu 2+ and other
guests besides Cl - can be isolated. In fact, we have already prepared a Co 2+ containing derivative
with a structure different from 1. Furthermore, the cage-like structure of 1 allows studies in host–
guest chemistry, ion exchange, gas storage, catalysis and medicine to be envisaged. Additional
derivatives of [H 7 P 8 W 48 O 184 ] 33- will be discussed in subsequent chapters.
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