Novel Low Spin Mixed Ligand Thiohydrazide Complexes of Iron(III): Synthesis, Spectral Characterization, Molecular Modeling, and Antibacterial Activity

Mixed ligand complexes of Fe(III) with aromatic thiohydrazides of general composition [Fe(acac)(L)2] have been synthesized and characterized (acac-acetylacetonate, L = bidentate uninegative aromatic thiohydrazide ligand, for example, thiobenzhydrazide, 2-hydroxythiobenzhydrazide, furan-2-thiohydrazide, and thiophen-2-thiohydrazide). The magnetic susceptibility data and the EPR spectra of these complexes suggested the formation of rhombically distorted low spin iron center (d5) in octahedral environment, which was also supported by the UV-vis spectral data of the complexes. Biological studies of these complexes also indicated that the iron-thiohydrazido complexes have superior antibacterial properties compared to the corresponding ligands.