Metal Complexes which React Irreversibly with Dioxygen

1 Metal Complexes which React Irreversibly with Dioxygen 

The irreversible coordination of dioxygen to metal complexes is of remarkable importance in order to explain the activity of enzymes such monooxygenases, dioxygenases and cytochrome c oxidase. 

Monooxygenases, by incorporation of a single atom of dioxygen in reactions of the type  

A dinuclear Fe(II) centre is bridged by two carboxylate and one hydroxide group. It is thought that the activation of molecular oxygen is a consequence of the ability of the active site to shuttle the FeuFen/ FeIIFeIII/FeIIIFeIn redox changes. 

Dioxygenases, by incorporation of both the atoms of the dioxygen molecule, catalyse degradation reactions of aromatic derivatives according to the following mechanisms  

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The use of models that mimic a protein active site is normally prompted by the desire to eliminate any influence of the polypeptide backbone surrounding the active site in real biological molecules, which may obscure its physico-chemical properties. The first attempts to synthesize metal complexes similar to the active site of haemoproteins, through the use of simple metalloporphyrin derivatives, failed. The failure was due to the fact that these complexes react irreversibly with dioxygen as a consequence of side autooxidative reactions of the type ... 

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