Geometric control of redox level in tetranuclear manganese and cobalt systems

A tetranucleating macrocyclic ligand derived from [2 + 2] Schiff-base conde nsation of 2,6-diformyl-4-methylphenol and 1,5-diaminopentan-3-ol was used to prepare a series of localised mixed-valence cobalt and manganese complex es. X-ray crystallographic structure analyses of one Co(II)(4) complex, two Mn(II)(2)Mn(III)(2) and two Co(II)Co(III)(3) complexes are presented. The observed redox levels are accounted for in terms of geometric constraints t ransmitted from one metal ion to the next through the ligand framework, pro viding a basis for cooperative control of redox processes. (C) 2000 Elsevie r Science S.A. All rights reserved.