Pyrazole-based ligands for the [copper-TEMPO]-mediated oxidation of benzyl alcohol to benzaldehyde and structures of the Cu coordination compounds

Abstract

New pyrazole-based ligands have been designed, and the catalytic performances of their copper(II) complexes for the [copper/TEMPO]-mediated oxidation of benzyl alcohol to benzaldehyde have been examined. The pyridine-pyrazole ligands give efficient catalysts, while the use of naphthol-pyrazole ligands results in inactive catalytic systems. Single-crystals of four Cu coordination compounds obtained from pyridine-pyrazole ligands and a free ligand have been isolated and were characterized by X-ray diffraction. Thus, the solid-state structures of three copper(II) complexes are described, together with a copper(I) coordination chain, exhibiting luminescent properties. © Wiley-VCH Verlag GmbH & Co. KGaA, 2007.