Synthesis of new coordination complexes 3d and 4f with Schiff bases. Structural and magnetic studies

Abstract

The main goal of this work was to obtain 3d and 4f polynuclear coordination compounds with Schiff bases as ligands and the study of their magnetic and structural properties. A few trials were carried out using Ni(II), Mn(II), Cu(II), Gd(III) and Dy(III), although only two compounds using Cu(II) and Mn(II) were able to crystallize. Their structures were successfully determined by X-ray diffraction. The copper compound crystallized as a dinuclear unit with formula C30H30Cl2Cu2N6O14, and a monomeric unit with formula C15H17Cl2CuN3O3 that co-crystallizes in the same crystal structure. The manganese complex was a dinuclear complex with formula C30H34Cl2Mn2N6O4 bridged by two chloride anions. Instead of the desired Schiff base, two new types of ligands were obtained due to an unexpected cyclization of one of the hydroxy groups leading to an oxazolidine ring in the first compound, and a rare double oxazolidine ring ligand that is able to complex the manganese (II) atoms in the second compound. Magnetic susceptibility measures were performed for both compounds. Compound 1 exhibits a weak antiferromagnetic coupling between the two Cu(II) metal ions, with an exchange constant J=-0.67 cm-1. Compound 2 exhibits a very weak antiferromagnetic coupling between the two Mn(II) metal ions, with an exchange constant J=-0.24 cm-1