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

The reaction of CuCl2 center dot 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(mu-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 CH3 group of the 4-aminoantipyrene unit of the Schiff base ligand is oxidized in situ to CH2OH, during the complex formation. The catalytic potential of the complex has been demonstrated in the synthesis of a series of 5-substituted 1H-tetrazoles via [3 + 2]-cycloaddition reactions of substituted benzonitriles and sodium azide in ethylene glycol. (C) 2018 Elsevier B.V. All rights reserved.