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

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, H-3-amsal, has been determined [H-3-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 Mn-III(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 H-1 NMR spectroscopies, FAB mass spectrometry, magnetic measurements, Lambda(M) and cyclic voltammetry.