SYNTHESIS AND STRUCTURE OF TETRADENTATE AMIDO-PHENOLATE MANGANESE(III) COMPLEXES - PRECURSORS FOR HIGH-VALENT MANGANESE CHELATE COMPLEXES

The synthesis and electrochemical properties of a range of manganese(III) complexes of a planar tetraanionic amido-phenolate ligand are described. The complexes are of general formula [MnL(A)(B)]- where L4- = 1,2-bis(2-hydroxy-benzamido)benzene anion; A and B are H2O or pyridine-type bases. The crystal structure of the six coordinate [MnLpy2]- moiety is described in the complex [Mn11py4(H2· O)2] [(MnIIILpy2)2]py2. The magnetic moment of the latter complex is 9.10 BM which is indicative of uncoupled MnII, MnIII, MnIII centres, The other complexes show S = 2 magnetic behaviour. Cyclic voltammetric studies on DMF solutions of the complexes show a reversible MnIII/MnIV wave at +0.67 V (relative to SCE) indicating that an oxidizing agent is required to obtain Mn(IV) species. © 1990.