Effect of F Substituents in Thiophenol on the Structure and Properties of µ2-S-(Difluorothiolate)tetranitrosyl Iron Binuclear Complexes

Abstract

Two new neutral binuclear tetranitrosyl iron complexes of general formula [Fe2R2(NO)4] with R = 2,4-difluorothiophenyl (complex 1) and 3,4-difluorothiophenyl (complex 2), donors of nitrogen monoxide (NO), were prepared. The complexes were characterized by single-crystal X-ray diffraction, IR, Mössbauer, EPR spectroscopy, and elemental analysis. The antibacterial activity and cytotoxicity of complex 1, complex 2, and previously synthesized [(NO)4] with R'= 2,4-dichlorothiophenyl (complex 3) were studied for the first time. The “amount of NO–biological activity” correlations were analyzed depending on the nature and position of the substituent in the thiophenyl ligand. Complex 2 was found to have antibacterial activity that was four times as high as that of the known antibiotic kanamycin. The anti-biofilm activity of complex 2 was studied; it inhibited 46% of biofilm formation and destroyed 32% of M. Luteus biofilms, surpassing the effects of the reference drugs kanamycin and ampicillin.