Synthesis, characterization, and x-ray crystallography of unexpected chloro-substitution on 1-(4-chlorophenyl)-3-phenylthiourea platinum(II) complex with tertiary phosphine ligand

Abstract

The reaction of 1-(4-chlorophenyl)-3-phenylthiourea (CPTH2) with [PtCl2(PPh3)2] moiety in a 1:1 molar ratio in a basic solution afforded unexpected Pt(II) thiourea dianion complex. The crystal structure revealed that the second phenyl ring of the parent ligand was substituted with a chlorine atom. Chlorine substitution on the phenyl ring might have been aided by the solvent CH2Cl2. The crystal structure revealed a platinum(II)-centered four-membered ring structure. FT-IR, 1H-NMR, and 31P-NMR spectroscopy were also utilized to study the complex. The crystal packing environment is explored by Hirshfeld surface analysis, enrichment ratio calculations and void analysis. Various quantum calculations were performed on both the ligand and its complex, and the calculated values were compared to the experimental ones. The energies of the two resonance structures of the CPTH2 ligand are very close. However, the stability of the thione form was slightly greater than that of the thiol form. The bond lengths and bond angles calculated by Orca for the Pt(II) complex were nearly identical to the experimental values. The biological assessment of the Pt(II) complex was evaluated against four pathogenic bacteria: Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Salmonella typhi (S. typhi). The Pt(II) complex exhibited moderate inhibition values against all bacterial species, with the exception of Pseudomonas aeruginosa (P. aeruginosa), which exhibited the greatest activity.