Thiourea Ligand Coordination in Nickel(ii) and Zinc(ii) Complexes: Experimental and Computational Investigations
DOI:
https://doi.org/10.11113/jomalisc.v5.128Keywords:
Coordination chemistry, Density-functional theory, Nickel(II) complexes, Thiourea, Zinc(II) complexesAbstract
Thiourea-based ligands exhibit versatile coordination behavior with transition metals; however, synthetic inconsistencies and unresolved structure–property profiles remain significant challenges in coordination chemistry. In this work, phenylthiourea (PTU) and N-(1-naphthyl)-N′-phenylthiourea (NPTU) were synthesized and coordinated with open-shell Ni(II) (d8) and closed-shell Zn(II) (d10) ions. The resulting complexes were characterized using ATR-FTIR, UV–Vis, and H NMR spectroscopy, complemented by density-functional theory and time-dependent DFT (TD-DFT) calculations to optimize molecular geometries and evaluate electronic features using B3LYP with 6-31G(d,p) and LANL2DZ. Spectroscopic and computational data confirmed successful coordination primarily through the thiocarbonyl sulfur atom. The Ni(II) complexes displayed pronounced red/blue structural shifts indicating strong covalent bonding, whereas Zn(II) complexes demonstrated weaker, mostly electrostatic interactions driven by its stable d10 configuration. Computational optimization aligned well with experimental results, confirming a square planar shape for Ni(II) and a tetrahedral geometry for Zn(II) complexes. This integrated approach successfully maps the coordination pathways of asymmetric thioureas, offering a reliable blueprint for predicting electronic properties in future material and life science applications.
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