New copper(II) μ-alkoxo-μ-carboxylato double-bridged complexes as models for the active site of catechol oxidase: synthesis, spectral characterization and DFT calculations.

A series of four copper(II) μ-Alkoxo-μ-carboxylato double bridged complexes, [{Cu(L)}][(μ-OC-CO] , [{Cu(L)}(μ-OC-(CH)CO] , [{Cu(L)}(μ-OC-CH-CO] and [{Cu(L)}(μ-OC-CH-CO] (HL = 4-bromo-2-((E)-((3-(((E)-5-chloro-2-hydroxybenzylidene) amino)-2-hydroxypropyl) imino) methyl)-6-methoxyphenol and μ-dicarboxylate ions = oxalate, malonate, succinate and terephthalate) have been synthesized and characterized using several physicochemical techniques. The tridentate nature of HL is interpreted from IR spectra. The Epr spectra of these complexes are characteristic of the quintet state (S = 2) in central features and the triplet state (S = 1) of these tetranuclear complexes.

Unprecedented tetranuclear complexes with "weighing balance shaped" topology: single crystal structures, unusual EPR spectra, magnetic properties and antioxidant activity.

Using the 2-hydroxy-N'-[(E)-phenyl(pyridin-2-yl)methylidene]benzohydrazide ligand and dicarboxylate anions (succinate and malonate), two new copper(ii) complexes of formula [Cu(μ-L)(μ-CH(COO))(HO)](NO)·4HO (1) and [Cu(μ-L)(μ-CH-CH(COO))(HO)](NO)] (2) have been synthesized and characterized by single crystal X-ray diffraction. Complexes 1 and 2 contain a dicarboxylate bridged tetranuclear Cu(ii) cationic unit with "weighing balance shaped" topology. These compounds have also been studied by variable temperature magnetic susceptibility measurements, X-band EPR spectroscopy and electrochemistry.