Metal Complexes which React Reversibly with Dioxygen

2 Metal Complexes which React Reversibly with Dioxygen 

Three main classes of metalloproteins able to coordinate reversibly dioxygen are known, namely  

A roughly similar Fe-02 arrangement has been found in human oxyhaemoglobin.6 

For some years the exact nature of the Fe-02 bond has been under discussion should it be viewed as Fen-02 or Fem-02 At present the Fem-OJ form is favoured. 

In the deoxygenated form, each Cu(I) centre is coordinated to three nitrogen atoms of three histidines. The great Cu/Cu separation (4.62 A) foreshadows the presence of a cavity able to host a dioxygen molecule. In fact, in the oxygenated form, the oxygen molecule is planarily positioned according to a p-rj2 r]2 peroxo coordination, and the Cu/Cu separation decreases (—3.5 A). 

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