Incomplete cubane-type clusters

II. Incomplete Cubane-Type Clusters with Mo304. S Cores... 

In contrast to the situation a decade ago, many incomplete cubane-type clusters with Mo304 S cores have been prepared and the structures have been determined by X-ray structure analyses. The results obtained are summarized in Tables I—III. The formal oxidation state of molybdenum in the compounds cited here is in all cases IV. Unlike Mo(VI) and Mo(V) compounds, mononuclear oxo or dioxo compounds of the Mo(IV) state are relatively rare and all the incomplete cubane-type compounds cited here have no terminal oxo ligand. Three Mo atoms form an equilateral triangle, and three single bonds exist between each Mo. Except for the compounds 1, 8, and 31 (Table III), and excluding Mo—Mo bonds, each molybdenum is octahedrally coordinated. 

Although the series is incomplete, cubane-type clusters with Mo404- S (n = 0,3, or 4) cores have been prepared and structures have been determined by X-ray crystallography. The results are summarized in Tables IV (53-57) and V (58-71). Contrary to the case of incomplete cubane-type clusters, wherein only the IV oxidation state of molybdenum appears, the oxidation state of molybdenum varies from VI to III. The total oxidation number of each Mo4 cluster is indicated in the tables. 

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