N.V. Izarova, N. Vankova, A. Banerjee, G.B. Jameson, T. Heine, F. Schinle, O. Hampe, U. Kortz, Angewandte Chemie International Edition 2010, 49, 7807-7811 (Paywall)
Contributed by Marcel Swart
Polyoxometalates are clusters of metals connected together through oxygens, and can be giant molecules such as {(MoVI)MoVI5O21}12(MoV2O4)30]12- (also known as Mo132) as shown by Bo and Miró in Dalton Transactions recently[1]. These clusters bear a total anionic charge, for instance -12 in the aforementioned example. However, this is not the complete picture.
Ulrich Kortz (Univ. Bremen) visited Girona a couple of months ago and reported an interesting example of how theory can be useful. His group was working on a "A Noble-Metalate Bowl", and when trying to reproduce the 51V NMR spectrum computationally, it was impossible to get good agreement. By introducing Na/K cations they did get more and more reasonable results, and only obtained good agreement after having introduced 7 potassiums (or alternatively 6 potassiums and 1 sodium).
At first, the experimental people did not believe the calculations, because they had their mind set on the fact that polyoxometalates carry a large negative charge, and not a positive one. However, after doing electrospray mass spectrometry, indeed they observed mainly two peaks:
1) a singly charged molecular cation {K7[Pd7V6O24(OH)2]}+ (with seven potassiums)
2) a singly charged molecular cation {Na1K6[Pd7V6O24(OH)2]}+ (with six potassiums)
Therefore, contrary to popular belief, polyoxometalates are cationic!
[1] C. Bo, P. Miró, Dalton Trans. 2012, 41, 9984-9988
This work is licensed under a Creative Commons Attribution 3.0 Unported License.
Contributed by Marcel Swart
Polyoxometalates are clusters of metals connected together through oxygens, and can be giant molecules such as {(MoVI)MoVI5O21}12(MoV2O4)30]12- (also known as Mo132) as shown by Bo and Miró in Dalton Transactions recently[1]. These clusters bear a total anionic charge, for instance -12 in the aforementioned example. However, this is not the complete picture.
Ulrich Kortz (Univ. Bremen) visited Girona a couple of months ago and reported an interesting example of how theory can be useful. His group was working on a "A Noble-Metalate Bowl", and when trying to reproduce the 51V NMR spectrum computationally, it was impossible to get good agreement. By introducing Na/K cations they did get more and more reasonable results, and only obtained good agreement after having introduced 7 potassiums (or alternatively 6 potassiums and 1 sodium).
At first, the experimental people did not believe the calculations, because they had their mind set on the fact that polyoxometalates carry a large negative charge, and not a positive one. However, after doing electrospray mass spectrometry, indeed they observed mainly two peaks:
1) a singly charged molecular cation {K7[Pd7V6O24(OH)2]}+ (with seven potassiums)
2) a singly charged molecular cation {Na1K6[Pd7V6O24(OH)2]}+ (with six potassiums)
Therefore, contrary to popular belief, polyoxometalates are cationic!
This work is licensed under a Creative Commons Attribution 3.0 Unported License.
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