Geometric control of redox level in tetranuclear manganese and cobalt systems

Abstract

A tetranucleating macrocyclic ligand derived from [2+2] Schiff-base condensation 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 complexes. X-ray crystallographic structure analyses of one Co(II) 4 complex, two Mn(II) 2Mn(III) 2 and two Co(II)Co(III) 3 complexes are presented. The observed redox levels are accounted for in terms of geometric constraints transmitted from one metal ion to the next through the ligand framework, providing a basis for cooperative control of redox processes.