Unprecedented formation of a μ-oxobridged polymeric copper(II) complex: Evaluation of catalytic activity in synthesis of 5-substituted 1H-tetrazoles

Abstract The reaction of CuCl 2 ·2H 2 O with Schiff base ligand, 4-[(2-hydroxy-3-methoxybenzylidene)amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3-one] (hmdpH), in 1:1 molar ratio led to a novel and unprecedented oxo-bridged polymeric copper (II) complex, [Cu( μ -O) (hmdp)] n . The complex was isolated as crystalline solid and characterized by FTIR, UV–visible and EPR spectroscopic techniques. The molecular structure of the complex was also determined by single crystal X-ray diffraction studies. The formation of the complex is unique and unprecedented in the sense that one of the CH 3 group of the 4-aminoantipyrene unit of the Schiff base ligand is oxidized in situ to CH 2 OH, during the complex formation. The catalytic potential of the complex has been demonstrated in the synthesis of a series of 5-substituted 1 H -tetrazoles via [3 + 2]-cycloaddition reactions of substituted benzonitriles and sodium azide in ethylene glycol.