Reactions with Changes in Cluster Oxidation State

1 Reactions With Changes in Cluster Oxidation State 

Redox reactions are very frequent in the chemistry of transition metal complexes. d-orbitals are forming there many relatively low-lying occupied and 

Because of the nature of metal clusters, assignation of oxidation numbers to individual metal atoms as it is usually made for mononuclear species does not make sense in the case of metal aggregates. Cluster polyatomic metal nucleus must be considered as a whole, so only average oxidation numbers or states can be assigned to individual atoms. 

Degradation processes leading to a diminution in the number of metal-metal bonds with concomitant formation of metal-ligand bonds imply in general cluster oxidation. On the other hand, the conversion of metal-ligand bonds in metal-metal bonds increasing thus the cluster nuclearity implies in general a decrease in the oxidation state of involved metal atoms and thus a reduction of the cluster species as a whole. 

In the following description of cluster reactions involving changes in cluster oxidation states both electrochemical and chemical processes will be considered. In order to systematize the chemical redox processes, they have been roughly cataloged as reduction, oxidation, or additive oxidation reactions. 

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