Experimental and computational studies on copper(II) Schiff base complex derived from 4-acetyl-3-methyl-1-phenyl-2-pyrazolin-5-one

A new tetradentate N2O2 type Schiff-base ligand (H2L) was synthesized from the condensation of 4-acetyl-3-methyl-1-phenyl-2-pyrazoline-5-one with 2,2-dimethyl-1,3-propanediamine. The corresponding Cu(II) complex (CuL) was also synthesized. The ligand and the complex were characterized by FTIR and UV-Vis spectroscopy and elemental analysis. 1H- and 13C NMR spectra of the ligand and X-ray crystal structure of the complex were obtained. The main non-covalent intermolecular interactions were studied by Hirshfeld surface analysis and finger print plots. Due to the different structural possibility including imine‐one, amine‐ol, and amine-one forms for H2L compound, their conformational and geometrical aspects were investigated computationally by DFT/ M06-2X-6-311+G(d,p) methods. The computational results suggested that the amine-one is the most favorable tautomeric form.