Polyoxoanions molybdate

The vanadate (1, 2), molybdate (1-5), and tungstate (1-3) systems have been described in previous reviews. Although the focus in this chapter is on more recent developments, earlier well-established knowledge is included where needed for perspective and also to present a coherent picture of the hydrolysis behavior of these oxyanions. Equilibria of mono- and polynuclear species are described and information about known structures are given. Some recent work about mixed polyoxoanions is briefly reviewed. 

The research also revealed new complexities and some questions are still to be answered. The molybdate(VI) system in particular needs further clarification regarding the existence of some polyions. More kinetic and thermodynamic data would also help to improve our understanding of these systems and perhaps lead to a general inclusive explanation of the mechanism of polyoxoanion formation. In this respect the new information about some structural preferences of the different metals in mixed polyoxoanions is of interest and a useful addition to known facts regarding polyoxometalate structures (181). 

In addition to the 12-molybdocerate complexes described in Section 2.1, and the Peacock-Weakley analogs listed in Table 4, there have been other attempts to synthesize rare-earth complexes of molybdates. In view of the inadequacies of 95Mo-NMR caused by low sensitivity and quadrupolar relaxation, and the ambiguities of other spectroscopic methods, it has so far been impossible to confirm whether those compounds that reveal discrete polyoxoanions in crystal structure analysis yield solutions that retain the same structures. 

Polyoxometalates can be versatile inorganic building blocks for construction of molecular-based materials. The use of polyoxometalates, in combination with inorganic or organic components has been realized in the construction of molecule-hased materials. Prominent examples of inorganic materials can he found in the work by Muller on giant molybdates.We have been interested in materials comprised of lanthanide polyoxoanion building blocks. We report herein our efforts in the studies of lanthanide complexes of [a-... 

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