Main group-transition metal mixed clusters

Current concepts in modem chemistry/Transition metal cluster chemistry/Main group-transition metal mixed clusters/Cluster compounds of main group elements/ Synthetic analogues of the active sites of iron-sulfur proteins... 

Although compounds with edge and face-bridging ligands may be formally considered as main group-transition metal mixed clusters (s. Chap. 3), in these section they will be referred to only as ligands. 

Main Group-Transition Metal Mixed Clusters... 

Table 3.2. Selected examples of main group transition metal mixed clusters with stoichiometries M4E, M5E, and MeE.

Table 3.3. Cluster valence electron counting in main group-transition metal mixed clusters...

The simplest and also the commonest among main group-transition metal mixed compounds are those in which the main group element caps a triangular array of metal atoms in any triangular or more complex deltahedral metal cluster thus forming units of the type (jU3-E)M3. 

For mixed main group-transition element clusters containing but one transition element, modifying the above electron-counting procedure to include the 6 nonbonding electron pairs on the transition metal has been advocated (128) as a way of bringing the electron count into line... 

In the latter case each 14-electron CpCo group completes its valence-shell by sharing electron pairs with one other CpCO group and with three phosphorus atoms, consistent with its diamagnetic character and with the observed geometry. It is likely that many more such mixed clusters, incorporating both transition metals and main group element, will be developed in the future. 

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