Bimetallic Systems and Mixed Valence

By dehnition, a supramolecular device comprises more than one component, and this may well involve two or more photophysically active or redox centres. The nature of the interaction between these components will depend strongly on the nature of the bridge between them. In the case of two interacting metal centres of the type discussed above, we can distinguish three classes of behaviour, denoted class I, II and 

If we consider the interaction between two valence-localised electronic isomers, in which the metal centres are of oxidation state +2 or -f3 (e.g. and there exist particular equilibrium ge- 

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