Binuclear manganese(III) complexes with carboxylate bridges: Synthesis, structure, electrochemistry and magnetic properties

A series of μ-oxo, μ-carboxylato binuclear manganese(III) complexes derived from bipy, phen and different carboxylate ligands have been prepared and characterized by IR and UV–vis spectroscopies, cyclic voltammetry, magnetic susceptibility and the X-ray crystallography. The electronic spectra of all the complexes show very similar features consisting of two absorptions in the visible region, one high intensity LMCT band and two intra-ligand transitions in the UV region. The cyclic voltammograms of the complexes exhibit four steps in most cases, each consisting of a one-electron transfer reaction. These probably correspond to Mn2III↔MnIVMnIII↔Mn2IV oxidation and Mn2III↔MnIIIMnII↔Mn2II reduction processes. The structure of complex 2 has been determined by the X-ray crystallography and consists of a binuclear [Mn2(bipy)2(μ-O)(μ-OOCR)2(NO3)(H2O)]+ cation (R = CH2Cl) with a ClO4- anion. Low temperature magnetic susceptibility measurements show that there is a weak ferromagnetic interaction in 1 (R = Ph) (J = +0.43 cm−1) and a weak antiferromagnetic interaction between the metal centers in 2 (R = CH2Cl) (J = −0.15 cm−1).

A series of μ-oxo, μ-carboxylato binuclear manganese(III) complexes derived from bipy, phen and different carboxylate ligands have been synthesized.Figure optionsDownload as PowerPoint slide