Mononuclear Mn(III) and dinuclear Mn(III, III) Schiff base complexes: Influence of π–π stacking on magnetic properties

Synthesis of a mononuclear Mn(III) (1) and a dinuclear Mn(III, III) (2) complex of a tetradentate N2O2 donor Schiff base ligand with ancillary carboxylate ligands are reported. Complex 1 crystallizes in the monoclinic space group C2/c, complex 2 in the triclinic space group P-1. In both complexes the central Mn(III) ions are hexacoordinated having a distorted octahedral MnN2O4 coordination environment. Intermolecular hydrogen bonding and strong π–π stacking in both 1 and 2 leads to dimerization of 1 and formation of a syn–anti one-dimensional chain for 2. Magnetic properties of 1 and 2 are reported. Both complexes show very weak intermolecular antiferromagnetic interaction. Most interestingly the major contribution for the exchange coupling arises from a superexchange pathway involving π–π interaction.

Graphical abstractSynthesis, structural characterization and magnetic properties study of one mononuclear Mn(III) (1) and one dinuclear Mn(III, III) (2) complex of a tetradentate N2O2 donor Schiff base ligand with ancillary carboxylate ligands are reported. π–π Stacking and presence of intermolecular hydrogen bonding are observed in both cases. Magnetic study shows that both the complexes exhibit weak antiferromagnetic exchange interactions.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Discrete monomeric Mn(III) and dimeric Mn(III, III) complexes of a N2O2 donor ligand. ► Existence of intermolecular hydrogen bonding and prominent π–π stacking. ► Dimeric Mn(III, III) complex exhibits syn–anti one dimensional chain. ► Both the complexes show weak antiferromagnetic intermolecular interactions.