Synthesis, Characterization and Antimicrobial Activities of Co (III) and Fe (III) Complexes of Imino-N-heterocyclic Carbenes Ligands

Abstract

The synthesis and antimicrobial application of Co (III) and Fe (III) complexes of imine functionalized N-heterocyclic carbene (Imino-NHC) ligands is reported. The ligand precursors 1-(2-[(hydroxyl-benzylidene)-amino]-ethyl)-3-R-3H-imidazol-1-ium bromide where R = pyridyl (1a) and benzyl (1b) have been reported in our previous work. The in-situ generated ligands of 1a and 1b have been successfully coordinated to CoBr2 and [FeI(Cp)(CO)2] leading to the isolation of air-stable N^C^N^O four coordinate Co(III)  complex 2 and a six-coordinate Fe(III) complex 3. The synthesised complexes were both found to be NMR inactive hence were characterize using FTIR and LRMS. The complexes were screened for antimicrobial activities against four gram-negative bacteria Escherichia Coli (E-coli), Shigella, Klebsiella pneumoniae (K. Pneumoniae) and Salmonella typhi (S. typhi) and a gram positive bacteria Staphylocossus aureus (S. aureus). The antimicrobial test was conducted using disc diffusion methods and based on the concentrations of 100, 200, 300, 400 and 500 µg/ mL, significant activities were recorded for both cobalt and the iron complexes.