COOPERATIVE BIMETALLIC REACTIVITY

A number of bimetallic complexes of a macrocyclic binucleating ligand containing both six-and four-coordinate binding sites have been prepar ed in order to try to reproduce the behavior of certain metalloprotein s. It was found that two-metal oxidation is severely impeded in bimeta llic systems. It is postulated that the mutual deactivation of metal o xidation is principally the result of unfavorable ligand conformationa l adjustments which occur after the first metal is oxidized. It is sho wn that when these conformational restraints are removed, two-metal ox idations are possible. (C) 1998 Elsevier Science S.A.