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

Abstract

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 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 (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 a = 13.222(1) Å, b = 15.912(1) Å, c = 14.149(1) Å, beta = 91.64(1) degrees, and Z = 4.

New unsymmetric dinuclear CuIICuII complexes and their relevance to copper(II) containing metalloenzymes and DNA cleavage

“…These distances are in agreement with those detected in other mononuclear and dinuclear pentacoordinate Cu II complexes containing Cu II -OH phenol and Cu II -O phenolate in their structures [15]. The bridging angle l-phenolate (Cu1-O1-Cu2) increases from 95.90(1)°to 99.87 (11)°whereas that of the l-OCH 3 (Cu1-O2-Cu2) bridge becomes slightly smaller (104.10(1)°to 103.93(12)°) in changing from 1 to 2 and so the Cu II Á Á ÁCu II distances are also comparable in the two complexes (3.075(1) in 1 and 3.037(1) Å in 2) and are also in agreement with those found for other (l-phenolate)(l-methoxy) complexes described in the literature [44]. In catechol oxidase, the distance between the two copper centers is 2.9 Å [2-6].…”

Structural Basis and Mechanism of the Inhibition of the Type-3 Copper Protein Tyrosinase from Streptomyces antibioticusby Halide Ions

“…see Refs. [32][33][34][35][36][37][38][39], and it has also been proposed for both met and half-met hemocyanin (11,26,27,60). We note that exchange of the Cu 2 bridging ligand would affect the magnitude of antiferromagnetic coupling (i.e.…”

Structural, magnetic, electrochemical, catalytic, DNA binding and cleavage studies of new macrocyclic binuclear copper(II) complexes

“…The spectra of the complexes consists three bands. A low intensity band in the region 610-660 nm (e % 220 M À1 cm À1 ) is indicative of square pyramid geometry [30], and a shoulder in the region 350-400 nm is attributed to the phenolato to Cu(II) charge-transfer band (e % 25,000 M À1 cm À1 ). The third one or more intense peaks below 300 nm assigned to the intraligand charge-transfer transitions (e % 20,000 M À1 cm À1 ).…”