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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.

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: Ruthenium(II) carbonyl complexes containing triarylphosphines and hybrid ligands PPh2-X (X= o-dimethylaniline – P–N, o-pyridine – P-Py, or o-anisole – P–O) were synthesized and characterized. Six new complexes with the formula cis,trans-[RuCl2(CO)(PPh2-X)(PR3)] (X= o-dimethylaniline, R=Ph 1a; X= o-pyridine, R=Ph 2a; X= o-anisole, R=Ph 3a; X= o-dimethylaniline, R= p-tol 1b; X= o-pyridine, R= p-tol 2b; and X= o-anisole, R= p-tol 3b) were obtained by starting from the appropriate precursors, [RuCl2(CO)(DMF)(PPh3)2] or [RuCl2(CO)(DMF)(P{p-tol}3)2]. The two chlorine atoms are in cis position to each other, and the monophosphine (PPh3 or P{p-tol}3) is in trans position to the nitrogen or oxygen of the PPh2-X ligand. The synthesized complexes were characterized by 1D–1H, 31P{1H} and 2D-correlations HMBC 31P–1H NMR, vibrational spectroscopy, elemental analysis, and X-ray diffraction structural determination (for complexes 1a, 2a·CH2Cl2 , 3a, and 3b·CH2Cl2 ). Only the complexes containing the P–O ligand (3a and 3b) reacted with carbon monoxide (at 1atm and room temperature). The NMR (31P{1H}, 1H) data was compatible with carbon monoxide coordination at the OCH3 position, which led to the formation of dicarbonyl complexes [RuCl2(CO)2(P–O)(PR3)] (R=Ph 4a or p-tol 4b), and proved the hemilabile behavior of the P–O ligand. In addition, the complexes underwent isomerization in solution when exposed to ambient light, and the products were analyzed by 31P{1H} NMR. The X-ray structures and the chemical shift in the 31P NMR spectra were correlated and discussed. [Copyright &y& Elsevier]

Abstract: The mixed ruthenium(II) complexes trans-[RuCl2(PPh3)2(bipy)] (1), trans-[RuCl2(PPh3)2(Me2bipy)](2), cis-[RuCl2(dcype)(bipy)](3), cis-[RuCl2(dcype)(Me2bipy)](4) (PPh3 = triphenylphosphine, dcype = 1,2-bis(dicyclohexylphosphino)ethane, bipy = 2,2′-bipyridine, Me2bipy = 4,4′-dimethyl-2,2′-bipyridine) were used as precursors to synthesize the associated vinylidene complexes. The complexes [RuCl(h name="dbnd" />CHPh)(PPh3)2(bipy)]PF6 (5), [RuCl(h name="dbnd" />CHPh)(PPh3)2(Me2bipy)]PF6 (6), [RuCl(h name="dbnd" />CHPh)(dcype)(bipy)]PF6 (7), [RuCl(h name="dbnd" />CHPh)(dcype)(bipy)]PF6 (8) were characterized and their spectral, electrochemical, photochemical and photophysical properties were examined. The emission assigned to the π–π∗ excited state from the vinylidene ligand is irradiation wavelength (340, 400, 430 nm) and solvent (CH2Cl2, CH3CN, EtOH/MeOH) dependent. The cyclic voltammograms of (6) and (7) show a reversible metal oxidation peak and two successive ligand reductions in the +1.5-(−0.64) V range. The reduction of the vinylidene leads to the formation of the acetylide complex, but due the hydrogen abstraction the process is irreversible. The studies described here suggest that for practical applications such as functional materials, nonlinear optics, building blocks and supramolecular photochemistry. [Copyright &y& Elsevier]

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]

• 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]

Abstract: The synthesis and characterization of trans/cis-[RuCl2(dppf)(diimines)], dppf=1,1′-bis(diphenylphosphino)ferrocene; diimines=2,2′-bipyridine (trans/cis-(1)), the new complexes with 4,4′-dimethyl-2,2′-bipyridine (trans/cis-(2)) and 1,10-phenanthroline (cis-(3)) are presented. The complexes were synthesized using two routes and the trans/cis-isomer formation is dependent upon conditions and the precursor applied. The trans-isomer (kinetic) readily isomerizes to the cis-isomer (thermodynamic) when exposed to light (fluorescent) and this process was followed by cyclic voltammetry and UV–vis. The electrochemical studies on these complexes reveal that Fe(III)/Fe(II) couples are insensitive to the isomer (trans/cis) formed, but the Ru(III)/Ru(II) couples are dependent on the isomer. Transfer-hydrogenation reactions for reduction of acetophenone were conducted using complexes cis-(1) and cis-(2) and the results are compared with that obtained for similar complexes. X-ray structure for cis-(3) are presented and discussed. [Copyright &y& Elsevier]

The triphosphines-containing ruthenium-acetato complexes [RuCl(κ2-OAc)(triphos)] (2) and the new analogue synthesized in our research group [RuCl(κ2-OAc)(etp)] (1) (triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane or etp = bis[2-(diphenylphosphino)ethyl]phenylphosphine) were evaluated as pre-catalyst for the dehydrogenation of formic acid (FA). Complex [RuCl(κ2-OAc)(etp)] (1) was fully characterized by 1H, 13C and 31P{1H} NMR, vibrational spectroscopy, elemental analysis and X-ray diffraction. The electrochemical behavior of 1 and 2 was checked by cyclic voltammetry. DFT calculations for 1, 2 and for the two isomers of 1 (1′ and 1") were performed and discussed. Due to the linear nature of etp ligand, three isomeric forms for [RuCl(κ2-OAc)(etp)] (1′ and 1") are possible and were observed. Both complexes were active for the decomposition of FA, in three solvents (MeOH, THF and i PrOH), at 80 °C, leading solely to formation of CO 2 and H 2. In THF both complexes achieved quantitative conversions (in times up to 125 min) and final TOF's up to 833 h−1, for complex 1. Image 1 • Ruthenium-acetato containing triphosphine ligands. • fac/mer isomerization and stability. • DFT and frontier orbitals and reactivity/activity. • Efficient and selective dehydrogenation of formic acid. [ABSTRACT FROM AUTHOR]