Synthesis, characterization and thermodynamic study of copper(II) complexes with unsymmetric tetradentate Schiff base ligands and X-ray structure of {methyl-2-[N-[2-(5-chloro-2-phenolate)methylidynenitrilo]ethyl}aminato(-1)-1-cyclopentenedithiocarboxylatecopper(II)

A set of two Cu(II) complexes, [Cu(cdXsalen)] and [Cu(cdXsalMeen)] derived from Schiff base ligands (H(2)cdXsalen: methyl-2-{[2-(2-X-phenyl)methylidynenitrilo]ethyl}amino-1-cyclopentenedithiocarboxylate and H(2)cdXsalMeen: methyl-2-{[1-methyl-2-(2-X-phenyl)methylidynenitrilo]ethyl}amino-1-cyclopenteneithiocarboxylate where X = hydroxyl, methoxy, nitro, sodiumsulfite, chloro, bromo and H(2)cdMesalen: methyl-2-{[2-(2-hydroxyphenyl)ethylidynenitrilo]ethyl}amino-1-cyclopentenedithiocarboxylate; H(2)cdPhsalen: methyl-2-{[2-(2-hydroxyphenyl)phenylidynenitrilo]ethyl}amino-1-cyclopentenedithiocarboxylate; H(2)cdMesalMeen: methyl-2-{[1-methyl-2-(2- hydroxyphenyl)ethylidynenitrilo]ethyl}amino-1-cyclopentenedithiocarboxylate; H(2)cdPhsalMeen: methyl-2-{[1-methyl-2-(2-hydroxyphenyl)phenylidynenitrilo]ethyl}amino-1-cyclopentenedi-thiocarboxylate) with an unsymmetric NNOS coordination sphere have been synthesized and characterized by elemental analysis, IR, UV-Vis and mass spectrometry. The thermodynamic formation constants of the complexes were measured spectrophotometrically, at constant ionic strength 0.1 M (NaClO4), at 25 degrees C in DMF solvent. The trend of the complex formation for copper is as follow: [Cu(cdMesalen)] > [Cu(cdsalen)] > [Cu(cdPhsalen)] [Cu(cdMesalMeen)] > [Cu(cdsalMeen)] > [Cu(cdPhsalMeen)] and [Cu(cd5OMesalen)] > [Cu(cd3OMesalen)] > [Cu(cd4OMesalen)] [Cu(cd5OMesalMeen)] > [Cu(cd3OMesalMeen)] > [Cu(cd4OMesalMeen)] and [Cu(cd5OMesalen)] > [Cu(cdsalen)] > [Cu(cd5Brsalen)] > [Cu(cd5Clsalen)] > [Cu(cd5NO(2)salen)] > [Cu(cd5SO(3) Nasalen)] [Cu(cd5OMesalMeen)] > [Cu(cdsalMeen)] > [Cu(cd5BrsalMeen)] > [Cu(cd5ClsalMeen)] > [Cu(cd5NO(2)salMeen)] > [Cu(cd5SO(3)NasalMeen)] and [Cu(cdXsalMeen > [Cu(cdXsalen)]. The structure of {methyl-2-[N-[2-(5-chloro-2-phenolate)methylidynenitrilo]ethyl}aminato(-1)-1-cyclopentene-dithiocarboxylatecopper(II), [Cu(cd5Clsalen)], has been determined by X- ray crystallography. The complex shows normal planar geometry around the copper center. (c) 2009 Elsevier B.V. All rights reserved.