Syntheses, Reactivity, X-ray Structures, and Antioxidant Properties of Ruthenium(II) Complexes with Aryl/Ferrocenyl-Fluorodithiophosphate Ligands [PPh4][(X)FPS2] (X = p-Methoxy-C6H4, p-Ethoxy-C6H4, Ferrocenyl).

Reaction of Lawesson's reagent analogue precursors with dry potassium fluoride as the fluorinating agent in the presence of tetraphenylphosphonium bromide gave three aryl/ferrocenyl-fluorodithiophosphate ligands [PPh4][(p-methoxy-C6H4)FPS2] (L1), [PPh4][(p-ethoxy-C6H4)FPS2] (L2), and [PPh4][(Fc)FPS2] (L3) (Fc = Fe(η5-C5H4)(η5-C5H5)). The treatment of [(η6-p-cymene)RuCl2]2 (η6-p-cymene = 1-methyl-4-iso-propyl-benzene) with equivalent L1 and L3 in dichloromethane afforded a binuclear ruthenium(II) complex [(η6-p-cymene)Ru{κ2-S,μ-S'-(p-methoxy-C6H4)FPS2}]2 (1) and a mononuclear ruthenium(II) complex [(η6-p-cymene)ClRu{κ2-S,S'-(Fc)FPS2}] (2), respectively. Interaction of cis-[(phen)2RuCl2] (phen = o-phenanthroline) with L1 and L2 in methanol at reflux gave mononuclear ruthenium(II) complexes trans-[(phen)2Ru{(κ1-S-(p-methoxy-C6H4)FPS2)}2] (3) and trans-[(phen)2Ru{(κ1-S-(p-ethoxy-C6H4)FPS2)}2] (4), respectively. Precursors pre-L1-pre-L3, ligands L1-L3, and ruthenium(II) complexes 1-4 were well-characterized by IR, NMR, UV-vis, and TOF-MS spectroscopies. The structures of precursor pre-L3, ligands L1 and L3, and ruthenium(II) complexes 1-4 have been established by single-crystal X-ray crystallography. Moreover, the antioxidant properties of ruthenium(II) complexes 1-4 were evaluated using DPPH free radical and ABTS cation radical-scavenging activities in vitro.