Synthesis, characterization, and antimicrobial studies of half-sandwich η6-toluene ruthenium complexes with N,N′-bidentate ligands

Abstract

Nine new complexes [(η6-C6H5-CH3)RuLCl]+(PF6)ˉ (where L = N,N′-bidentate ligand; (C5H4NCH = N-Ar) where Ar = 4-methylphenyl (C20H20ClF6N2PRu, 1); 3,4-dimethylphenyl (C21H22ClF6N2PRu, 2); 2,4,6-trimethylphenyl (C21H24ClF6N2PRu, 3); 4-bromophenyl (C19H17ClBrF6N2PRu, 4); 2,5-dimethylphenyl (C21H22ClF6N2PRu, 5); 2-flourophenyl (C19H17ClF7N2PRu, 6), (4-methoxyphenyl)methylene (C21H22ClF6N2OPRu, 7); phenylmethylene (C20H20ClF6N2PRu, 8); and 3,5-dimethylphenyl (C21H22ClF6N2PRu, 9) were synthesized by reacting the corresponding N,N′-bidentate ligands with the ruthenium arene dimer in a 2:1 ratio. The compounds were fully characterized via 1H NMR and 13C NMR, IR, and UV-vis spectroscopy and elemental analyses. The molecular structures of representative complexes (1, 7, and 8) were established by single-crystal X-ray diffraction studies. In the molecular structures of the complexes, the ligands coordinate to the Ru(II) centers via the pyridine nitrogen atom and the imine N atom in a bidentate manner. The other coordination sites of the Ru(II) center are occupied by the tolyl system in an η6 manner resulting in geometry often referred to as “pseudo-octahedral piano-stool.” All compounds were evaluated for their in vitro antibacterial activity by the disk diffusion method against a panel of Gram-negative and Gram-positive bacteria. The complexes showed promising bactericidal activity against methicillin-resistant Staphylococcus aureus ATCC 43300.