Synthesis and characterization of new symmetrical binucleating ligands and their μ-phenoxo-bridged bicopper(II) complexes:: Structural, electrochemical, and magnetic studies

The new pentadentate binucleating ligands 2,6-Bis[N-(3,5-dimethyl-2-hydroxybenzyl)-N-methylaminomethyl]-4- chlorophenol, H(3)L(1), and 2,6-bis[N-(3,5-dichloro-2-hydroxybenzyl)-N-cyclohexylaminomethyl]-4-methylphenol, H(3)L(2), and their binuclear copper(II) complexes of the general formulas [Cu(2)L(1)(X)] (X = OMe, OH, Br (1-3)) and [Cu(2)L(2)(X)] (X = OMe, OH, Br (4-6)) have been prepared. The molecular structure of the complex [Cu(2)L(1)(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 Angstrom. A cyclic voltammetric study of the complexes shows two quasireversible reduction waves at negative potentials. A cryomagnetic investigation on powdered samples of the complexes (1-6) 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 [Cu(2)L(1)(OMe)]. MeOH: molecular formula C(30)H(39)ClCu(2)N(2)O(5), monoclinic, space group P2(1)/c with p = 13.222(1) Angstrom, b = 15.912(1) Angstrom, c = 14.149(1) Angstrom, beta = 91.64(1)degrees, and Z = 4.