Chalcogen-capped clusters

The chalcogen-capped clusters M M2Co(/(3-S)(CO)s()/ -CsH5) (M M2 = MoEc, MoRu, WFe) and MoFeCo(/r ,-Se)(CO)H()) -CsH3) underw ent a one-electron, quasi-reversible reduction. Addition of an electron proceeded more readily for the clusters w ith the lighter metals and for the selenium capped cluster relative to its sulfur analogue. 

Fig. 6.1 The fundamental structural unit found in the Chevrel phases (cluster MoeXg full circles Mo atoms) displayed in three ways to emphasize different views of the connectivity. In (a) an octahedron of molybdenums (Mo-Mo = 2.7 A) is encased in a cube of chalcogens (Mo-S 2.45 or Mo-Se 2.6 A). Scheme (b) exhibits the same cluster as consisting of an octahedron with its triangular faces capped by chalcogenides. In (c), the cluster has been reoriented so that a threefold axis is vertical. (Reproduced from [10])...

The dichalcogenide clusters are isostructural, and the basic cluster geometry of these consists of a Fe2Mo2 tetrahedron with the two Mo2Fe faces capped by / -chalcogen atoms. In all of these, one of the Mo atoms possesses... 

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