Synthesis and metal complexes of a chelating ligand containing thiomorpholine and pyridine: 2,6-bis(thiomorpholinomethyl)pyridine

Abstract

A chelating ligand, 2,6-bis(thiomorpholinomethyl)pyridine (L), was synthesised. Its palladium (II), copper(II) and nickel(II) complexes of the formula ML(NO 3) 2, (MPd, Cu and Ni), were prepared and characterised. The molecular structures of the three complexes were determined by X-ray diffraction. In all the compounds prepared the ligand acts in a tridentate fashion using its three N atoms while the two S atoms remain free. The Pd complex possesses a distorted square planar coordination geometry with one of the two nitrato groups coordinating as a unidentate ligand and the other ionic. The PdN (pyridine) bond length is 1.857(4) Å, which is believed to be the shortest PdN separation ever observed. In the Cu complex, the copper atom is five-coordinated in a distorted square planar arrangement with the two nitrato groups acting as unidentate ligands and occupying the apex and one equatorial position. The Ni complex has a distorted octahedral coordination sphere: one nitrato group behaves in a chelating fashion and the other unidentate.