2-Acetyl-5-chloro-thiophene thiosemicarbazone and its nickel(II) and zinc(II) complexes: Hirshfeld surface analysis and Density Functional Theory calculations for molecular geometry, vibrational spectra and HOMO-LUMO studies

Abstract

In this work, the theoretical studies on the molecular structure are presented for 2-Acetyl-5-chloro-thiophene thiosemicarbazone and its Ni(II) and Zn(II) complexes. The optimized molecular geometry and fundamental vibrational frequency values have been investigated with the help of DFT/B3LYP method using 6-31G(d,p) basis set and they are found to be in agreement with the experimental values. Additionally, frontier molecular orbital energies (HOMO, LUMO) and their energy gaps (∆E) are calculated by the same method. The HOMO and LUMO analysis are used to determine some molecular properties such as chemical potential, hardness, softness and electronegativity. Furthermore, Hirshfeld surface analyses and fingerprint plots have been used for visualizing and exploring intermolecular interactions in the crystal structure and for determining the percentage contribution of these interactions on the surface. The Hirshfeld surface analysis and the 2D fingerprint plots indicate that the crystal packing of the compounds is dominated by Cl···H/H···Cl, S···H/ H···S, N···H/ H···N and H···H contacts.