Synthesis, Crystal Structure, and Electrochemical Properties of Two New Manganese Complexes With a Ligand Derived From 1,2-Propanediamine and 2-Hydroxy-5-Methoxybenzaldehyde

Abstract

Two new homo binuclear manganese(III) complexes, [Mn (L)(H2O)]2(PF6)2, where [H2L = N,N′-Bis(2-hydroxy-5-methox- ybenzylidene)-propane-1,2-diamine] have been prepared by reaction of N,N′-bis(2-hydroxy-5-methoxybenzylidene)propane-1,2-diamine as a Schiff-base ligand, manganese(II) acetate and ammonium hexafluorophosphate. The complexes were characterized by spectral, structural and electrochemical studies. X-ray structural analysis shows the presence of dimanganese core in the complexes and the binding of the ligands to the manganese(III) is through N2O2. The dimeric unit is formed by a double Mn–O bridge of one molecule with its centrosymmetric homologue. The crystal structure of the complexes indicates that in the solid state the complex adopts an octahedral environment of the imine N and hydroxo O with the one axial H2O ligand around manganese. There are two coordination/chelation environments present around two manganese centers of each binuclear complex. The electronic spectra of the complex show red shift in the d–d transition. The electrochemical reduction of these complex at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Mn(III)–Mn(II) is electrochemically quasireversible in the range of 0 to −1.0 V.