N,N′-dipyridoxyl(ethylenediamine) schiff-base ligand and its square-pyramidal copper(II) complex: Synthesis, experimental and theoretical characterization

A new tetradentate N,N′-dipyridoxyl(1,2-ethylenediamine) [=H 2 ES] Schiff-base ligand and its Cu(II) salen complex [Cu(ES)(H 2 O)] are synthesized and characterized by IR, UV-Vis, 1 H NMR, mass spectrometry, and elemental analysis. Their optimized geometries and theoretical vibrational frequencies are computed by using the density functional theory method where the B3LYP functional was used. Also, the 1 H NMR chemical shifts of the H 2 ES ligand are calculated at the same computational level. In the optimized structure of the free ligand, two pyridine rings are not in the same plane. In the structure of the complex, the Schiff-base ligand acts as a dianionic tetradentate ligand in the N, N, O − , O − manner, so that the coordinating atoms occupy equatorial positions. The H 2 O ligand occupies the axial position of the squarepyramidal complex. The calculated results are consistent with the experimental ones, confirming the suitability of the optimized structures for the H 2 ES ligand and its Cu(II) complex.