Expanding the Family of Tetrahalide Iron Complexes: Synthesis, Structure and Biological Applications.

A neutral octahedral mononuclear iron(II) tetrabromide complex, [Fe(Hampy)₂Br₄], that consists of equatorial bromide and protonated aminopyrazinium axial ligands is successfully synthesised through redox chemistry and analysed using X-ray crystallography. The iron(II) oxidation state is balanced by the protonated pyrazinium nitrogen just outside the coordination sphere. The biological properties of this and two other related complexes are investigated using both Gram-negative and Gram-positive bacteria as well as methicillin resistant strains. They all exhibit some antimicrobial properties albeit at moderate to poor concentrations. However, the tetrahalide complexes analysed exhibit excellent anti biofilm properties well below cytotoxic levels.