Synthesis, characterization and crystal structure of a novel thiazoline/thiazolidine azine ligand and its nickel, copper and zinc complexes

Abstract

The new ligand N-(2-acetyl-2-thiazoline)- N′-(2-thiazolidin-2-one) azine (ATHTd) has been synthesized and characterized by X-ray diffraction, elemental analysis, 1H and 13C NMR spectra, elemental analysis, IR and UV–Vis spectra. Also the complexes [NiCl(ATHTd)(H 2O) 2]Cl ( 1), [Ni(ATHTd) 2](NO 3) 2·H 2O ( 2), [CuCl 2(ATHTd)] ( 3) and [ZnCl 2(ATHTd) 2] ( 4) have been isolated and characterized in the solid state by X-ray diffraction, elemental analysis, IR spectroscopy, UV–Vis–NIR diffuse reflectance, magnetic susceptibility measurements and, in the case of copper(II) complex, EPR spectroscopy. X-ray data indicate that the environment around nickel atoms in 1 and 2 may be described as a distorted octahedral geometry. In 1 the metal ion is coordinated to one chloride ligand, one water molecule and one ATHTd molecule which acts as a tridentate ligand, while in 2 Ni(II) is coordinated to two tridentate ATHTd molecules. With regard to 3, the coordination geometry around copper(II) ion can be considered a distorted square pyramid with the cation coordinated to one tridentate ATHTd ligand and two chloride ligands. Finally, in the case of 4, the Zn(II) is bonded to two ATHTd molecules that acts as a monodentate ligand and two chloride atoms in a distorted tetrahedral geometry. The structure of ATHTd in the complexes presents an amino-2-thiazoline form instead of the iminothiazolidine one observed in free ATHTd. Another significant structural change in complexes, except in 4, is due to the different degree of rotation of the thiazoline rings around the C(1)–C(4) and C(6)–N(3) bonds, which permit the coordination through thiazolinic nitrogen atoms.