Spectral and structural density functional theory on 4-ethyl and 4-(p-tolyl)-1-(pyridin-2-yl)thiosemicarbazides and their Pd(II) complexes

The study deals with the experimental and theoretical calculations of 4-ethyl and 4-(p-tolyl)-1-(pyridin-2-yl)thiosemicarbazides and their Pd(II) complexes. Quantum chemical calculations of geometry, vibrational wavenumbers, 1H NMR and Natural Bond Orbital (NBO) analysis of the ligands and their Pd(II) complexes have been carried out by DFT/B3LYP method combined with 6-311++G(d,p) and DGTZVP basis sets. The geometry optimized structures of the ligands confirming the involvement of N1H in intramolecular H-bond with the. The DFT calculated spectral data showed good agreement with the experimental data supporting the obtained geometries for the ligands and Pd(II) complexes. The NBO analysis confirmed the formation of bonds with sulfur, σ(Pd-S), and nitrogen (N1) described as donation of electron density from a lone pair orbital on each nitrogen atom to palladium orbitals.