Synthesis and Spectroscopic characterization of new Co, Ni, and Cu complexes with ligands derived from coumarin

Abstract

In this thesis, the present work involved the preparation of four series of new heterogeneous compounds from coumarin. These compounds contain a compound known as (Coumarin) or 3-acetyl-7-hydroxy-2H Chromine-2-one within the central nucleus. The preparation of these compounds involved a series of reactions, beginning with alkylation reactions (1a-i), esterification reactions (3a-i)., Schiff bases reactions (4a i), finally, complexes formation reactions Cobalt (II) (5a-i), Nickel (II) (6a-i) and Copper (II) (7a-i). The first series of new coumarin derivatives (4a-i), or the so-called ligands, were prepared from the reaction of coumarin derivatives (3a-i) with tiosemicarbazide. These compounds contain (n-alkoxy) terminal chains be odd or even parity. This group of compounds showed colors ranging from light yellow to dark yellow . The structure of these compounds was elucidated by UV-Vis, FT-IR spectroscopy, 1H-NMR, 13C-NMR. The second series of new derivatives of coumarin Cobalt (II) (5a-i), Nickel (II) (6a-i) and Copper (II) (7a-i) or the so-called complexes. It was prepared through a reaction between a series of coumarin derivatives (4a i) with metals chlorides (CoCl2.6H2O, NiCl2.6H2O, CuCl2.2H2O) solid in a molar ratio of 2:1. The structure of these compounds was demonstrated by infrared techniques FT-IR, UV-Vis, LC-Mass spectroscopy, 1H NMR, 13C-NMR. The FT-IR spectra of the as-prepared complexes revealed distinct bands that differ from those in the ligand spectrum. This is due to the occurrence of bonding between metal ions and ligands atoms; by means of the nitrogen and oxygen atom in the homologous ring in the ligands molecule. The molar conductivity of the cobalt, nickel and copper complexes (dissolved in DMSO) was measured at a concentration (1×10-3 molar). The results showed that all the complexes do not possess the ionic character and that their solutions are of a non-electrolytic nature. As for the results of magnetic sensitivity measurements, they showed that the complexes possess (paramagnetic) properties. The expected geometries of these complexes were proposed by coordinating the ligands molecules with the metal ion nucleus. The results obtained for the complexes under study, show the octahedral geometry. The following scheme shows the preparation of the series compounds with metals .