Synthesis, spectral studies and antibacterial activity of iron(III) complexes with hydrazone functionalized ligands: X-Ray structure determination of a novel five coordinate complex containing labile ligands

Abstract

Iron(III) complexes having general formula FeLCl 2 [where, L = 2-acetylpyridine acetoylhydrazone(APAH), 2-acetylpyridine benzoylhydrazone(APBH), 2-acetylthiophene acetoylhydrazone(ATAH), and 2-acetythiophene benzoylhydrazone(ATBH) ] have been synthesized characterized based on molar conductivity, electronic and IR spectroscopy. The structure of iron(III) complex with APBH ligand is determined using single crystal X-Ray crystallography . The complex crystallizes in monoclinic space group P21/n with a = 7.8490(6) Å, b = 15.1018(11) Å, c = 13.2263(10) Å, α = 90°, β=100.183(3)°, γ = 90°, V = 1543.1(2) Å3 and Z = 4 with central Fe(III) ion coordinated one tridentate APBH ligand. The iron is 5- coordinate binding with one organic (hydrazone) unit and two labile chloride ligands. The hydrazone acts as NNO –tridentate donor system. Iron is coordinated by pyridine ring nitrogen, azomethine nitrogen and benzoyl oxygen atoms and the two chloride ligands bind with metal completing distorted square pyramidal structure. The iron complexes are screened for their anti-bacterial activities against Pseudomonas aureoginos and Bacillus cereus Acetoyl hydrazones show more antibacterial activity than the corresponding benzoyl hydrazones. Functional groups of azomethine carbon are varied. The hydrazones having a methyl/ and pyridine groups show more anti bacterial activity. The complexes show more activity than the ligands.