A direct route to obtain manganese(III) complexes with a new class of asymmetrical Schiff base ligands

Abstract

A new class of asymmetrically substituted Schiff base ligands has been synthesised incorporating hard amido donor atoms. The single crystal X-ray structure of one of these ligands, H3-amsal, has been determined [H3-amsal=3-aza-4-(2-hydroxyphenyl)-N-(2-hydroxyphenyl)but-3-enamide]. The structure reveals the ligand to be suitable for use as an equatorially co-ordinating ligand in octahedral complexes. A new route to obtaining manganese(III) complexes of these ligands, with high yield and purity, has been designed. Complexes of the form MnIII(amsal-R)(H2O)n (n=1–4) have been prepared by the electrochemical oxidation of a manganese anode in an acetonitrile solution of the ligands. The compounds have been characterised by elemental analyses, IR and 1H NMR spectroscopies, FAB mass spectrometry, magnetic measurements, ΛM and cyclic voltammetry.