A chloro bridged Cu(II)-Cu(II) complex of a new aminophenol ligand: Magnetostructural, radical decay kinetic studies, highly efficient and aerial alcohol oxidation

A new tripodal aminophenol-based ligand containing a pyridine unit was synthesized and characterized by IR and H-1 NMR spectroscopic techniques. A dimeric copper(II) complex of this ligand was prepared and characterized by X-ray crystallography, DFT calculations, spectroscopic techniques and magnetic susceptibility measurements. X-ray analysis revealed a complex in which one phenolate, and amine and imine nitrogens of the ligand are arranged in a distorted square pyramidal geometry (SP) around the copper ions. Two chloride bridges hold both copper atoms together to form the binuclear [(LCuCl)-Cu-Aph](2) complex. This complex exhibits nearly no superexchange coupling between the copper centers. The phenolate moieties of the copper complex were electrochemically oxidized to phenoxyl radical cations [(LCuCl)-Cu-Aph](2)(center dot+). The decay kinetics of the mentioned radical were investigated using a simulation of the voltammogram data. In addition, highly efficient and eco-friendly oxidation of alcohols to aldehydes was achieved with molecular oxygen or air as the oxidant and the [(LCuCl)-Cu-Aph](2)-Cs2CO3 system as a catalyst. (c) 2012 Elsevier Ltd. All rights reserved.