Synthesis, structures, and catalytic studies of new copper(II) complexes with arene-linked pyrazolyl methane ligands
Two new copper complexes, [Cu2(L1)(dipic)2(H2O)2]⋅2H2O (1) and [Cu2(L2)(dipic)2(H2O)2]⋅3H2O (2) (L1 = 1,4-bis((1H-pyrazol-1-yl)methyl)benzene; L2 = 1,4-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)benzene; and H2dipic = 2,6-pyridinedicarboxylic acid), were synthesized by the reaction of copper salt, arene-linked pyrazolyl methane ligands, and 2,6-pyridinedicarboxylic acid in 95% C2H5OH. They were characterized by elemental analysis, IR, UV–vis, single-crystal X-ray diffraction analysis, X-ray powder diffraction, and thermogravimetric analysis. We explored the application of the copper complexes in bromination reactions; the complexes exhibited bromination catalytic activity in single-pot reaction for the conversion of phenol red into bromophenol blue. A feasible bromination reaction mechanism of copper complexes was proposed.
