Spectroscopic characterization (IR and NMR), structural investigation, DFT study, and Hirshfeld surface analysis of two zinc(II) 2-acetylthiophenyl-thiosemicarbazone complexes

Abstract

• Zn(II) compounds are structurally characterized by single-crystal X-ray diffraction. • FT-IR and 1H NMR spectroscopy analyses are also performed. • FT-IR and 1H NMR are reported and compared with the calculated results. • The Hirshfeld analysis is used to investigate the intermolecular interactions. Zinc(II) complexes with 5-chloro-2-acetylthiophen-4-methyl-3-thiosemicarbazone and 5-methyl-2-acetylthiophen-4-methyl-3-thiosemicarbazone ligands were characterized by FT-IR, 1 H NMR, single-crystal X-ray diffraction and Hirshfeld surface analysis. In both complexes, metal centers are four–coordinated in a distorted tetrahedral configuration by two sulphur atoms from two thiosemicarbazone ligands and two Cl anions. In the crystal packing of two compounds, intermolecular interactions generate cyclic symmetry–related dimeric structures but different supramolecular arrangement. Also, intramolecular hydrogen bondings were found for both complexes. The Hirshfeld surface analysis and the 2D fingerprint plots indicate that the packing is dominated by Cl···H/H···Cl, S···H/ H···S, C···H/ H···C and H···H contacts. Study of X-ray diffraction, as well as spectroscopic analysis of each complex shows that the thiosemicarbazone ligand coordinated to Zinc ion appears as a thione tautomer. In addition, Density Functional Theory (DFT) B3LYP with 6-31G(d,p) method was applied to clarify the spectroscopic results.