This work describes the synthesis, characterization, theoretical study of electronic structures and in vitro leishmanicidal activity of eight new ruthenium(II) complexes obtained from the cis-[RuCl2(dppm)2] and [RuCl2(ƞ 6-p-cymene)]2 precursors, where dppm=1,1-bis(diphenylphosphine)methane. The synthesized complexes were defined as cis-[Ru(O-O)(dppm)2]PF6 and [RuCl(O-O)(ƞ 6-p-cymene)], where O-O corresponds to the chelating β-diketones ligand: 1,3-butanedione-1-phenyl-4,4,4-trifluoro (BTA), 2thenoyltrifluoroacetone (TTA), 1,3-butanedione-1-(4-bromophenyl)-4,4,4-trifluoro (TFBr) and 1,3-butanedione-1-(4-fluorophenyl)-4,4,4-trifluoro (TFF), respectively. The empirical formulas, as well as the bidentate coordination (OO) modes of the inserted ligands and the geometries of the synthesized complexes were suggested by the techniques of elemental analysis (CHN), infrared spectroscopy (ATR-FTIR), 1 H (proton), 31 P{ 1 H} (phosphorus) and 19 F{ 1 H} (fluorine) nuclear magnetic resonance (NMR). The electron transitions observed in the UV-Vis spectra were confirmed by the theoretical calculations and for the crystals obtained from the [RuCl (ƞ 6-p-cymene)] complex, the technique for single-crystal X-ray diffraction confirmed the proposed structure. In vitro viability assays against the Leishmania (L.) amazonensis species, all the complexes were found to be active, with complexes derived from the cis-[RuCl2(dppm)2] precursor. The IC50 values obtained were between 24.7 μM and 3.9 μM, being comparable to values referring to the second choice compounds currently used in the treatment against leishmaniasis, which makes the complexes synthesized promising leishmanicidal agents.
