Abstract
Four tridentate ligands L-1-L-4, namely N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl) pyridin-2-amine: L-1, 5-chloro-N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl) pyridin-2-amine:L-2, N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)thiazol-2-amine:L-3 and N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)-6-methylpyridin-2-amine: L-4 were synthesized, characterized (by(13)C NMR, H-1 NMR and mass spectroscopy) and employed for the synthesis of copper(II) complexes in situ. These ligands contain three sp(2) nitrogen atoms, two pyrazole nitrogen and one pyridine nitrogen, capable of coordinating with copper (II). Then the catalytic properties of certain complexes formed in situ were evaluated to catalyze the oxidation of catechol to o-quinone. Among these complexes, the L-1/Cu(CH3COO)(2) complex which showed good catalytic activity of the combination 1:1 ligand/metal in THF for this reaction, with a reaction rate of oxidation of catechol to o-quinone equal to 26.37 mu mol L-1 min(-1).