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Synthesis and Characterization of New Symmetrical Binucleating Ligands and Their μ-Phenoxo-Bridged Bicopper(II) Complexes:  Structural, Electrochemical, and Magnetic Studies

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journal contribution
posted on 14.08.1998 by P. Amudha, M. Kandaswamy, L. Govindasamy, D. Velmurugan
The new pentadentate binucleating ligands 2,6-Bis[N-(3,5-dimethyl-2-hydroxybenzyl)-N-methylaminomethyl]-4-chlorophenol, H3L1, and 2,6-bis[N-(3,5-dichloro-2-hydroxybenzyl)-N-cyclohexylaminomethyl]-4-methylphenol, H3L2, and their binuclear copper(II) complexes of the general formulas [Cu2L1(X)] (X = OMe, OH, Br (13)) and [Cu2L2(X)] (X = OMe, OH, Br (46)) have been prepared. The molecular structure of the complex [Cu2L1(OMe)]·MeOH was studied by X-ray crystallography. It exists as a discrete binuclear species in which the copper atoms are in a distorted square planar environment with two oxygen bridges provided by the phenolate of the ligand and methoxy exogenous donor and the Cu···Cu distance is 3.030 Å. A cyclic voltammetric study of the complexes shows two quasireversible reduction waves at negative potentials. A cryomagnetic investigation on powdered samples of the complexes (16) shows moderately strong antiferromagnetic coupling (−2J in the range 120−300 cm-1). A comparison of the electrochemical and magnetic properties of the complexes prepared from both ligands is discussed. Crystal data for the complex [Cu2L1(OMe)]·MeOH:  molecular formula C30H39ClCu2N2O5, monoclinic, space group P21/c with a = 13.222(1) Å, b = 15.912(1) Å, c = 14.149(1) Å, β = 91.64(1)°, and Z = 4.