TUNGSTEN-183 NMR: A COMPLETE AND UNEQUIVOCAL ASSIGNMENT OF THE TUNGSTEN-TUNGSTEN CONNECTIVITIES IN HETEROPOLYTUNGSTATES VIA TWO-DIMENSIONAL 183W NMR TECHNIQUES.

Article abstract of DOI:10.1021/ja00362a008

The importance of polytungstates as model compounds for homogeneous or homogeneous-heterogeneous catalysis is now well recognized, because of the triangular array of their tungsten bridging oxygens on their surfaces which resemble metal oxide surfaces. On the other hand, **1**8**3W nuclear magnetic resonance has proven to be a very good tool for determining the overall symmetry and structure of such polytungstates. Numerous efforts have been undertaken to predict a confident assignment of each tungsten line and to study the electronic changes induced on the polytungstate anion shell in the 1-11 series by the introduction of heteroelements such as transition metals. The authors show that only direct proofs of the tungsten-tungsten connectivities allow an unambiguous conclusion, in contradiction with all the actually proposed methods.