Structural studies tungsten

Cluster anions, and their complexes with di- and trivalent transition metals thought to be based on XWii have been shown to be dimeric, based on structural studies of the salts of [Sb2W22074(0H)2] (40) and related species. The structure of this anionic cluster is shown in Figure 34, and comprises two B-/3-XW9 groups linked by two other tungsten atoms. Interestingly, two weakly bound tungsten atoms are bound to the periphery of the cluster and can be easily replaced by other transition metal ions. 

The ligand properties of 1 were investigated utilizing complex formation with W(CO)sTHF generated from the tungsten hexacarbonyl W(CO)6 (Scheme 4) in a falling-film photoreactor. The crude product is a pale yellow and microcrystalline material, soluble in CDCI3. Crystals suitable for X-ray structural studies have not been obtained so far. 

Molecular transition metal oxides ab initio and density functional electronic structure study of tungsten oxide clusters " ... 

A. G. Robiette, K. Hedberg, and L. Hedberg, J. Mol. Struct., 37, 105 (1977). Gas-Phase Electron Diffraction Study of the Molecular Structure of Tungsten Oxytetrafluoride, WOF4. 

The polymerization of acidified solutions of molybdenum(VI) or tungsten(VI) yields the most complicated of all the polyanion systems and, in spite of the fact that the tungsten system has been the most intensively studied, it is still probably the least well understood. This arises from the problem inevitably associated with studies of such equilibria, and which were noted (p. 983) in the discussion of the Group 5 isopolyanions. It must also be admitted that, whilst the observed structures of individual polyanions are reasonable, it is often difficult to explain why, under given circumstances, a particular degree of aggregation or a particular structure is preferred over other possibilities. 

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