Crystal structures and DFT analysis of Palladium(II) complexes with Schiff bases derived from N,N-dialkyl-p-phenylenediamines

Abstract

Herein, new palladium(II) complexes with Schiff bases derived from salicylaldehyde and N,N-dialkyl-p-phenylenediamines were obtained. The ligands 2-((4-(N,N-dimethylamino)aniline)formimidoyl)phenol (N,N-metph-sOH - L1) and 2-((4-(N,N-diethylamino)aniline)formimidoyl)phenol (N,N-etph-sOH - L2) and complexes [Pd(N,N-metph-sO)2] (C1) and [Pd(N,N-etph-sO)2] (C2) were characterized by elemental analysis, infrared (IR) and UV–Vis spectroscopy, 1H and 13C nuclear magnetic resonance (NMR), thermogravimetry (TG) and differential thermal analysis (DTA), and the results agree with the proposed structures. The crystal structures data showed the formation of N,O-chelate with the pairs of phenolate O and imine N occupying the trans positions. Hirshfeld surface analysis was employed to elucidate the intermolecular contacts which drive the different supramolecular assemblies of C1 and C2. In addition, Density Functional Theory (DFT) calculations were also performed to better understand the electronic properties. Additional DFT calculations were also devoted to elucidate the stereochemistry of these palladium complexes toward the cis-trans isomerism among these square-planar Pd(II) N,O-Schiff base complexes. Time-dependent DFT (TD-DFT) analysis was applied to shed light on the nature of the electronic transitions determined in the UV–Vis spectra.