(E)-4-(((2-amino-5-chlorophenyl)imino)methyl)-5-(hydroxy-methyl)-2-methylpyridin-3-ol and its Cu(II) complex: Synthesis, DFT calculations and AIM analysis

Herein, ( E )-4-{[(2-amino-5-chlorophenyl)imino]methyl}-5-(hydroxymethyl)-2-methylpyridin-3-ol [ HL ] Schiff base and its [Cu(L)Cl] complex were newly synthesized and characterized by several spectroscopic methods. In addition, density functional theory (DFT) methods were used for investigation of the tautomerization of the HL Schiff base, structural parameters of HL and [Cu(L)Cl] species, assignment of the IR vibrational bands and the NMR chemical shifts as well as natural bond orbital (NBO) analyses. The most stable tautomer of the HL Schiff base is the enol form of the meta isomer. The optimized geometry of the free HL Schiff base is not planar. The L - acts as a N2O tridentate ligand, which is bonded to Cu2+  via the deprotonated phenolic oxygen, and the amine and azomethine nitrogens. The [Cu( L )Cl] has a square planar geometry in which the chloro ligand occupies the fourth coordination position. The DFT-computed values are in good consistency with the corresponding experimental values, confirming the suitability of the optimized geometries for HL and [Cu( L )Cl] species. According to the high-energy gaps, these compounds are stable. The atoms in molecule (AIM) analysis was used to evaluate strength of the bonding interactions and electron densities in structure of the compounds.