Half-sandwich arene ruthenium, rhodium and iridium thiosemicarbazone complexes: synthesis, characterization and biological evaluation

Abstract

A series of ruthenium, rhodium and iridium complexes with 4-phenyl-1-(pyridin-4yl)methylene thiosemicarbazide (L1) and 4-phenyl-1-(pyridin-4yl)ethylidene thiosemicarbazide (L2) ligands were synthesized and isolated with hexafluorophosphate as a counter ion. All these complexes were fully characterized with the help of FT-IR, UV-Vis, 1H NMR, 13C NMR and elemental analysis. An agar-well diffusion method was employed for evaluation of antibacterial activities against one Gram-positive bacteria Staphylococcus aureus and two Gram-negative bacteria Escherichia coli, Klebsiella pneumoniae. Antimicrobial activity evaluation revealed that Cp* rhodium complexes has a significant antibacterial activity for all the three strains, Cp* iridium and p-cymene ruthenium complexes have shown moderated activity against the microorganisms but none of the complexes surpass the activity of their reference drugs. Results indicated that all the complexes reported here inhibit the growth of bacteria. Synopsis. A series of ruthenium, rhodium and iridium complexes bearing thiosemicarbazide ligands were synthesized and isolated with hexafluorophosphate as counter ion. Antibacterial potencies of the compounds was reported against Staphylococcus aureus, Escherichia coli, and Klebsiella pneumonia and results shows that all the complexes reported here inhibit the growth of bacteria.