Synthesis and Structural Characterization of the Mononuclear Cobalt(II) Complex: {5,5′-Dihydroxy-2,2′-[o-phenylene-bis(nitrilomethylene)]diphenolato}cobalt(II) Dihydrate

The Schiff base ligand H 2 L·C 2 H 5 OH derived from the condensation reaction between o -phenylenediamine and 2,4-dihydroxybenzaldehyde as well as its mononuclear complex [CoL]·2H 2 O have been synthesized and characterized by X-ray crystallography, IR, 1 H NMR and UV–Vis analyses, and density functional theory (DFT B3LYP) calculations. The Co II ion has a slightly distorted square-planar coordination provided by tetradentate dianionic N 2 O 2 ligand L 2− . The spin state of the complex was determined as being S = 1/2. On the basis of DFT calculations, the UV–Vis absorption bands of the ligand can be assigned to the 1 A 1 → 1 B 2 (two) and 1 A 1 → 1 A 1 transitions, while for complex they correspond to the 2 A 2 → 2 B 1 (two) and 2 A 2 → 2 A 2 ones. Graphical Abstract Index Abstract The Schiff base ligand H 2 L·C 2 H 5 OH derived from the condensation reaction between o -phenylenediamine and 2,4-dihydroxybenzaldehyde as well as its mononuclear complex [CoL]·2H 2 O have been synthesized and characterized by X-ray crystallography, IR, 1 H NMR and UV–Vis analyses, and density functional theory (DFT B3LYP) calculations.