Synthesis, X-ray structure, spectroscopic, electrochemical properties and DFT calculation of a bridged dinuclear copper(II) complex

Abstract A bridged dinuclear Schiff base-type copper(II) complex, [(Cu 2 ( L 2 ) 2 CH 3 COO)] 2 [Cu(NO 3 ) 4 ]·2CH 3 COOCH 2 CH 3 ( HL 2  = 1-(2-{[( E )-3,5-dibromo-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), has been synthesized via complexation of Cu(II) nitrate trihydrate with HL 1 (2-(3,5-dibromo-2-hydroxyphenyl)-4-methyl-1,2-dihydroquinazoline-3-oxide, H is the deprotonatable hydrogen). During the reaction, the C–N bond in the HL 1 is converted into the C N–OH group in the ligand HL 2 . The Cu(II) complex was analyzed using IR and UV–Vis spectroscopy, elemental analysis and single-crystal X-ray crystallography. The spectroscopic data of the Cu(II) complex was compared with the ligand HL 1 . In the crystal, each complex links with four other molecules into an infinite 2-D supramolecular structure through intermolecular hydrogen bonding and π⋯π stacking interactions. Moreover, the electrochemical properties of HL 1 and Cu(II) complex have been studied by cyclic voltammetry. The powder EPR spectrun of the dinuclear Cu(II) complex indicated that the existence of an antiferromagnetic spin-spin interaction between the magnetically nonequivalent two Cu(II) ions. The geometries and electronic properties of both the ligand HL 1 and the Cu(II) complex were studied by DFT calculation.