Polymolybdate clusters

Increasing numbers of extremely large polyoxomolybdate anions, with ring-shaped and hollow stmctures have been described. These contain mixed-valence polymolybdate anions that are constmcted using common building blocks containing M02, Moe, and M08 units, some of which have no independent stable existence. This area of cluster molybdenum chemistry has been extensively reviewed. 

Recent years have seen the reports of increasing numbers of very large polyoxometalate anions. These may be divided into two classes (i) composite anions constructed of assemblies of simpler, usually lacunary, polyanions and (ii) mixed-valence polymolybdate anions which comprise common building blocks, e.g., Mo8, Mo6, and Mo2 clusters that have no separate, stable existence. 

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