Electron-containing rules

An important consequence of the nonutilization of tangential orbitals is that platinum clusters often do not obey the normal electron counting rules and appear to be electron deficient (19,21,29,58,75,76). Electron counts are usually intermediate between those found in normal transition metal clusters (58-68) and those observed in gold clusters (58,78), but no satisfactory general electron counting theory has been developed for Pt-containing clusters. In small Pt clusters constructed from PtL2 units, theoretical studies have shown that the total electron count depends on the relative orientation of the... 

The structure of [GagRe]- is shown below (Kehrwald et al 2001). It contains three bare Ga centers which are problematical for a simple cluster electron-counting approach. Apply an electron-counting rule and describe any unusual aspects of the cluster s electronic structure. 

Although it may not be surprising that the same set of electron-counting rules can be used to describe satisfactorily such similar compounds as boranes and carboranes, we should examine how far the comparison can be extended. Can Wade s rules, for example, be used effectively on compounds containing metals bonded to boranes or carboranes Can the rules be extended even further to describe the bonding in polyhedral metal clusters ... 

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