Synthesis and characterization of new manganese(III) complexes with asymmetrical ONSN Schiff bases

Manganese(III) complexes with asymmetrical ONSN tetradentate Schiff bases h ave been prepared. Ligands are derived from the iminic condensation of subs tituted salicylaldehydes and 4-[(2'-amino-ethyl)thiomethyl]-5-methylimidazo le (H2MIS-X) or 2-[(2-aminoethyl)thiomethyl]-benzimidazole (H2BIS-X). Physi cochemical data (mean) indicate that ligands act as tetradentate mono- or d ianionic, in di- and mono-cationic complexes, respectively. [Mn(MIS-X)(H2O) ]ClO4 . nH(2)O, [Mn(BIS-X)(H2O)]ClO4 and [Mn(HMIS-X) (H2O)](ClO4)(2) . nH(2 )O (n = 0, 2, 4) have been characterized by elemental analyses, Lambda(M), IR, UV-VIS and mass spectrometries, magnetic measurements at room temperatu re and cyclic voltammetry, being their low solubility a handicap. These dat a, point to an octahedral geometry around the metal with, at least, a dimer ic array through the phenolic oxygen atoms. (C) 1998 Elsevier Science Ltd. All rights reserved.