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Complexes with general formula [RuCl(η6-p-cymene)(P–NR–P)]X (R = CH2Py (Py = pyridine) – [1a]+, CH2Ph (Ph = phenyl) – [1b]+, Ph – [1c] and p-tol (p-tol = p-tolyl) – [1d]+; X = PF6− or BF4−) were evaluated as cytotoxic agents against two cancer cell lines (HeLa and MDA-MB-231). All metal complexes are active in the range of concentrations tested (up to 100 μmol L−1). The IC50 (μmol L−1) values for the metal complexes are lower than that found for cisplatin. The activities are up to 6- and 15-fold higher than cisplatin for HeLa and MDA-MB-231 cancer cell lines, respectively. Studies of DNA binding and DNA cleavage were performed. DNA binding studies revealed a modest hypochromic shift in the metal complexes electronic spectra, indicating a weak interaction with Kb values in the range of 1.7 × 103–1.6 × 104. Although the cleavage tests revealed that in the dark DNA is not a biological target for these metal complexes, upon blue light irradiation they are activated causing DNA cleavage. Electrochemical studies showed the presence of two independent redox processes, one attributed to the oxidation process of Ru2+ → Ru3+ (EC process) and the other one to the reduction of Ru2+ → Ru1+, which is further reduced to Ru0 (ECE mechanism). In both processes, coupled chemical reactions were observed. DFT calculations were performed to support the electrochemical/chemical behavior of the complexes. The reactivity of complex [1b]BF4 with CH3CN was evaluated and two complexes were isolated [2b]BF4 and [3b]BF4. The complex mer-[RuCl(CH3CN)3(P–NCH2Ph–P)]BF4 ([2b]BF4) was isolated after refluxing the precursor [1b]BF4 in CH3CN. Isomerization of [2b]BF4 in CH3CN resulted in the formation of fac-[RuCl(CH3CN)3(P–NCH2Ph–P)]BF4. An attempt to isolate the fac-isomer by adding diethyl ether was unsuccessful, and the complex [3b]BF4 was observed as the major component. The complex [Ru2(μ-Cl3)(CH3CN)2(P–NCH2Ph–P)2]BF4 ([3b]BF4) proved to be very stable and can be obtained from both the mer- and the fac-isomers. The molecular structures of [1b]BF4 and [3b]BF4 were solved by single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Two new heterobimetallic ruthenium (II) complexes with general formula [Ru(N-S)(bipy)(dppf)]PF 6 (bipy = 2,2’-bipyridine, N-S = 2-mercaptothiazolinate – mctz − ( 1 ) and 2-mercaptobenzothiazolinate – mcbtz − ( 2 ); dppf = 1,1’-bis{diphenylphosphino}ferrocene) were synthesized from the reaction of cis- [RuCl 2 (bipy)(dppf)] and 2-mercaptothiazoline (Hmctz) or 2-mercaptobenzothiazoline (Hmcbtz), in the presence of triethylamine (NEt 3 ) and KPF 6 in MeOH, under reflux. The complexes were characterized by NMR ( 31 P{ 1 H}, 1 H and 13 C), vibrational spectroscopy (FTIR), cyclic voltammetry, molar conductivity, UV-Vis and elemental analysis (%C, %H, %N, and %S). Furthermore, the molecular structure of complexes 1 and 2 were solved by X-ray diffraction studies. UV-Vis spectroelectrochemistry studies were carried out for complex 2 in order to unravel the processes observed in the cyclic voltammetry. DFT analysis of complexes 1 , 2 and the precursor complex cis- [RuCl 2 (bipy)(dppf)] revealed the composition of the frontiers orbitals, supporting the assignment of the electrochemical behavior of the complexes. The antibacterial potential of the new complexes and the free ligands (dppf, mctz − and mcbtz − ) were assessed in vitro against Staphylococcus aureus, Staphylococcus epidermidis, E. coli and P. aeruginosa. The 1,1-diphenyl-2-picrilhidrazyl (DPPH) radical scavenging ability (antioxidant activity) was also evaluated. [ABSTRACT FROM AUTHOR]

Abstract: Complex fac-[RuCl3(NO)(P–N)] (1) was synthesized from the reaction of [RuCl3(H2O)2(NO)] and the P–N ligand, o-[(N,N-dimethylamino)phenyl]diphenylphosphine) in refluxing methanol solution, while complex mer,trans-[RuCl3(NO)(P–N)] (2) was obtained by photochemical isomerization of (1) in dichloromethane solution. The third possible isomer mer,cis-[RuCl3(NO)(P–N)] (3) was never observed in direct synthesis as well as in photo- or thermal-isomerization reactions. When refluxing a methanol solution of complex (2) a thermally induced isomerization occurs and complex (1) is regenerated. The complexes were characterized by NMR (31P{1H}, 15N{1H} and 1H), cyclic voltammetry, FTIR, UV–Vis, elemental analysis and X-ray diffraction structure determination. The 31P{1H} NMR revealed the presence of singlet at 35.6 for (1) and 28.3ppm for (2). The 1H NMR spectrum for (1) presented two singlets for the methyl hydrogens at 3.81 and 3.13ppm, while for (2) was observed only one singlet at 3.29ppm. FTIR Ru–NO stretching in KBr pellets or CH2Cl2 solution presented 1866 and 1872cm−1 for (1) and 1841 and 1860cm−1 for (2). Electrochemical analysis revealed a irreversible reduction attributed to RuII–NO+ →RuII–NO0 at −0.81V and −0.62V, for (1) and (2), respectively; the process RuII →RuIII, as expected, is only observed around 2.0V, for both complexes. Studies were conducted using 15NO and both complexes were isolated with 15N-enriched NO. Upon irradiation, the complex fac-[RuCl3(NO)(P–N)] (1) does not exchange 14NO by 15NO, while complex mer,trans-[RuCl3(NO)(P–N)] (2) does. Complex mer,trans-[RuCl3(15NO)(P–N)] (2′) was obtained by direct reaction of mer,trans-[RuCl3(NO)(P–N)] (2) with 15NO and the complex fac-[RuCl3(15NO)(P–N)] (1′) was obtained by thermal-isomerization of mer,trans-[RuCl3(15NO)(P–N)] (2′). DFT calculation on isomer energies, electronic spectra and electronic configuration were done. For complex (1) the HOMO orbital is essentially Ru (46.6%) and Cl (42.5%), for (2) Ru (57.4%) and Cl (39.0%) while LUMO orbital for (1) is based on NO (52.9%) and is less extent on Ru (38.4%), for (2) NO (58.2%) and Ru (31.5%). [Copyright &y& Elsevier]

Abstract: The “Ru(P–P)” unit (P–P=diphosphine) is recognized to be an important core in catalytic species for hydrogenation of unsaturated organic substrates. Thus, in this study we synthesized six new complexes containing this core, including the binuclear complex [(dppb)(CO)Cl2Ru-pz-RuCl2(CO)(dppb)] (pz=pyrazine) which can be used as a precursor for the synthesis of cationic carbonyl species of general formula [RuCl(CO)(dppb)(N–N)]PF6 (N–N=diimine). Complexes with the formula [RuCl(py)(dppb)(N–N)]PF6 were synthesized by exhaustive electrolysis of these carbonyl compounds or from the precursors [RuCl2(dppb)(N–N)]. The new complexes were characterized by microanalysis, conductivity measurements, IR and 31P{1H} NMR spectroscopy, cyclic voltammetry and X-ray crystallography. [Copyright &y& Elsevier]

• Ruthenium(II) thiazolines cotaining mono- and diphosphines complexes. • Redox dependence on the nature of thiazolines and phosphines. • 31P{1H} NMR correlation with structure of mono- and diphosphines and thiazolines. In this work, complexes containing mercaptothiazolines, and mono- and diphosphines with the general formula [Ru(N−S) 2 (P) 2 ] or [Ru(N−S) 2 (P-P)] – N–S−: 1,3-thiazoline-2-thionate (tzt− - a) and benzo-1,3-thiazoline-2-thionate (bzoxt− - b), and P 2 = monophosphine: P{ p -tol} 3 – 2 ; P-P = dppe – 3 , dppp – 4 , dppb – 5 , dppf – 6 or DPEPhos – 7 were synthesized. The complexes were characterized by 1H and 31P NMR, vibrational spectroscopy, elemental analysis, and the molecular structures of 3a, 4a, 5a, 6a •CH 2 Cl 2 and 7a were solved by X-ray diffraction. The Hirshfeld surface analysis and the 2D fingerprint plots were performed. The 1H NMR spectra of the compounds revealed the signals of the ligands and the main feature is the absence of the N H signal of the protonated ligands TztH and BzoxtH supporting the coordination in their anionic forms, which is also evidenced by the vibrational spectroscopy and molar conductivity studies. The 31P{1H} NMR spectra present only one singlet indicating the chemical equivalence of both phosphorus nuclei and in a region compatible with phosphorus cis -positioned for the P(p -tol) 3 and for the potentially trans -spanning dppf and DPEPhos, whereas for the other diphosphines (dppe, dppp and dppb) only the cis -configuration is expected. The molecular structure revealed the Ru center is sited on a distorted octahedral geometry mainly as a consequence of the formation of four-membered chelate rings involving the N–S− ligand. The coordination sphere is completed with two phosphorus atoms positioned in a cis -fashion while trans to the nitrogen atoms of the tzt− ligand, and the remaining sulfur donors (thiolate) of tzt− ligand positioned trans to each other. The cyclic voltammograms of the complexes presented one monoelectronic and reversible process attributed to the Ru3+/Ru2+ couple, and for the complexes with dppf an additional redox process is observed due to the Fe3+/Fe2+ couple. [ABSTRACT FROM AUTHOR]