Diorganotin Complexes with N(4)-Phenylthiosemicarbazones: Synthesis, Spectroscopic Characterization, and Antibacterial Activity

Abstract

The organotin(IV) complexes, SnPh₂L^a (1), SnMe₂L^a (2), SnBu₂L^a (3), SnPh₂L^b (4), SnMe₂L^b (5), SnPh₂L^c (6), SnMe₂L^c (7), and SnBu₂L^c (8) were obtained by reaction of SnR ₂Cl₂ (R = Ph, Me, and Bu) with 1-(5-bromo-2-hydroxybenzylidene)-4-phenylthiosemicarbazide (H₂L^a), 1-((2-hydroxynaphthalen-1-yl)methylene)-4-phenylthiosemicarbazide (H₂L^b), and 1-(2-hydroxy-3-methoxybenzylidene)-4-phenylthiosemicarbazide (H₂L^c). The synthesized complexes have been investigated by elemental analysis, IR, ¹H NMR, and ¹¹⁹Sn NMR spectroscopy. The data show that the thiosemicarbazone acts as a tridentate dianionic ligand and coordinates via the thiol group, imine nitrogen, and phenolic oxygen. The coordination number of tin is 5. The in vitro antibacterial activities of the ligands and their complexes have been evaluated against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and compared with the standard antibacterial drugs.

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GRAPHICAL ABSTRACT

Keywords:

• Thiosemicarbazones
• organotin
• antibacterial activity
• ¹¹⁹Sn NMR

Acknowledgments

Support of this work by Shahid Chamran University, Ahvaz, Iran (Grant No. 1392) is gratefully acknowledged.