Structure
Gouzerh summarises the historical views on the structure of phosphotungstic acid leading up to Keggin's determination of the structure as:
- H7 proposed by Miolati and further developed by Rosenheim
- H3 (Pauling)
The structure was determined by J.F Keggin first published in 1933 and then in 1934 and is generally known as the Keggin structure. The anion has full tetrahedral symmetry and comprises a cage of twelve tungsten atoms linked by oxygen atoms with the phosphorus atom at its centre. The picture on the right shows the octahedral coordination of oxygen atoms around the tungsten atoms, and that the surface of the anion has both bridging and terminal oxygen atoms. Further investigation showed that the compound was a hexahydrate not a pentahydrate as Keggin had proposed.
Read more about this topic: Phosphotungstic Acid
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