Cage effect metal complexes based

The stereochemical situation however, is appreciably more complex in incomplete corrins, such as cob(II)ester (24) and base-off forms of complete corrins. The axial ligand at the corrin-boimd Co(II) center is expected to direct the formation of the Co - C bond. In this way kinetic control can lead with high efficiency to the rare Q -alkyl-Co(III)-corrins [84,128[. In such radical recombination reactions the axial ligand at the a- or -side of the metal center will not only steer the diastereoselectivity of the alkylation but also may contribute to significant altering of the cage effects [122,123[. 

A number of electron acceptors have been identified for reaction (40) that can effectively mediate H2 evolution from water in the presence of Pt-group based redox catalysts. Typical examples are bipyridinium salts such as methyl viologen (MV " "), polypyridine complexes of Rh(III), Co(II) and cage complexes of Co(II). For this reason, the oxidative quenching of various transition metal polypyridine complexes, M(LL)3]" by these electron acceptors have been extensively studied ... 

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