Corrins corrin ring, general structure

The general structure of the Co(III) (oxidized) form of these organometallics is shown in Fig. 7.5. In Vitamin B 2 coenzyme (B a) the four coplanar ligands are provided by a corrin ring, the alkyl group is 5 -deoxyadenosyl and the Lewis base 5,6-dimethylbenzimidazole. Many model compounds have also been prepared, the chemistry of which mirrors to some extent that of the natural product. One of these systems is illustrated, in which the ligands are dimethylglyoxime (the cobaloximes). 

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