Mononuclear Ruthenium Complexes Research Articles

Photochemical, electrochemical, and photoelectrochemical water oxidation catalyzed by water-soluble mononuclear ruthenium complexes.

Two mononuclear ruthenium complexes [Ru(H2tcbp)(isoq)2] (1) and [Ru(H2tcbp)(pic)2] (2) (H4tcbp=4,4',6,6'-tetracarboxy-2,2'-bipyridine, isoq=isoquinoline, pic=4-picoline) are synthesized and fully characterized. Two spare carboxyl groups on the 4,4'-positions are introduced to enhance the solubility of 1 and 2 in water and to simultaneously allow them to tether to the electrode surface by an ester linkage. The photochemical, electrochemical, and photoelectrochemical water oxidation performance of 1 in neutral aqueous solution is investigated. Under electrochemical conditions, water oxidation is conducted on the deposited indium-tin-oxide anode, and a turnover number higher than 15,000 per water oxidation catalyst (WOC) 1 is obtained during 10 h of electrolysis under 1.42 V vs. NHE, corresponding to a turnover frequency of 0.41 s(-1). The low overpotential (0.17 V) of electrochemical water oxidation for 1 in the homogeneous solution enables water oxidation under visible light by using [Ru(bpy)3](2+) (P1) (bpy=2,2'-bipyridine) or [Ru(bpy)2(4,4'-(COOEt)2-bpy)](2+) (P2) as a photosensitizer. In a three-component system containing 1 or 2 as a light-driven WOC, P1 or P2 as a photosensitizer, and Na2S2O8 or [CoCl(NH3)5]Cl2 as a sacrificial electron acceptor, a high turnover frequency of 0.81 s(-1) and a turnover number of up to 600 for 1 under different catalytic conditions are achieved. In a photoelectrochemical system, the WOC 1 and photosensitizer are immobilized together on the photoanode. The electrons efficiently transfer from the WOC to the photogenerated oxidizing photosensitizer, and a high photocurrent density of 85 μA cm(-2) is obtained by applying 0.3 V bias vs. NHE.

Synthesis and Reactivity of Ruthenium Complexes Bearing Arsenic-Containing Arsenic-Nitrogen-Arsenic-Type Pincer Ligand

Dinuclear and mononuclear ruthenium complexes bearing an arsenic-containing arsenic-nitrogen-arsenic (ANA)-type pincer ligand are designed, prepared, and characterized by X-ray analyses. Both ruthenium complexes work as effective catalysts toward dehydrogenative transformations of alcohols.

Synthesis, characterization, and linkage isomerism in mononuclear ruthenium complexes containing the new pyrazolate-based ligand Hpbl.

A new tetradentate dinucleating ligand [1,1'-(4-methyl-1H-pyrazole-3,5-diyl)bis(1-(pyridin-2-yl)ethanol)] (Hpbl) containing an O/N mixed donor set of atoms has been synthesized and characterized by analytical and spectroscopic techniques. The Ru-Cl and Ru-aqua complexes containing this ligand of general formula [Ru(II)X(Hpbl)(trpy)](y+) (trpy = 2,2':6',2″-terpyridine; X = Cl, y = 1; X = H2O, y = 2) have been prepared and thoroughly characterized by spectroscopic and electrochemical techniques. The Ru-aqua complex 2 undergoes N → O linkage isomerization as observed electrochemically, and the related thermodynamic and kinetic parameters are extracted from cyclic voltammetry experiments together with DIGISIM, a CV simulation package. Under basic conditions an additional isomer is observed where the pyrazolyl group in the Hpbl ligand is replaced by the geminal pyridyl group. Further structural and electronic characterization of all the isomers has been carried out by means of DFT calculations.

New water oxidation chemistry of a seven-coordinate ruthenium complex with a tetradentate polypyridyl ligand.

The mononuclear ruthenium(II) complex [Ru](2+) (Ru = Ru(dpp)(pic)2, where dpp is the tetradentate 2,9-dipyrid-2'-yl-1,10-phenanthroline ligand and pic is 4-picoline) reported by Thummel's group (Inorg. Chem. 2008, 47, 1835-1848) that contains no water molecule in its primary coordination shell is evaluated as a catalyst for water oxidation in artificial photosynthesis. A detailed theoretical characterization of the energetics, thermochemistry, and spectroscopic properties of intermediates allowed us to interpret new electrochemical and spectroscopic experimental data, and propose a mechanism for the water oxidation process that involves an unprecedented sequence of seven-coordinate ruthenium complexes as intermediates. This analysis provides insights into a mechanism that generates four electrons and four protons in the solution and a gas-phase oxygen molecule at different pH values. On the basis of the calculations and corroborated substantially by experiments, the catalytic cycle goes through [(2)Ru(III)](3+) and [(2)Ru(V)(O)](3+) to [(1)Ru(IV)(OOH)](3+) then [(2)Ru(III)(···(3)O2)](3+) at pH 0, and through [(3)Ru(IV)(O)](2+), [(2)Ru(V)(O)](3+), and [(1)Ru(IV)(OO)](2+) at pH 9 before reaching the same [(2)Ru(III)(···(3)O2)](3+) species, from which the liberation of the weakly bound O2 might require an additional oxidation to form [(3)Ru(IV)(O)](2+) to initiate further cycles involving all seven-coordinate species.

ChemInform Abstract: Ruthenium‐Catalyzed Hydrohydroxyalkylation of Acrylates with Diols and α‐Hydroxycarbonyl Compounds to Form Spiro‐ and α‐Methylene‐γ‐butyrolactones.

Under the conditions of ruthenium(0)-catalyzed hydrohydroxyalkylation, vicinal diols 1a–1l and methyl acrylate 2a are converted to the corresponding lactones 3a–3l in good to excellent yield. The reactions of methyl acrylate 2a with hydrobenzoin 1f, benzoin didehydro-1f, and benzil tetradehydro-1f form the same lactone 3f product, demonstrating that this process may be deployed in a redox level-independent manner. A variety of substituted acrylic esters 2a–2h participate in spirolactone formation, as illustrated in the conversion of N-benzyl-3-hydroxyoxindole 1o to cycloadducts 4a–4h. Hydrohydroxyalkylation of hydroxyl-substituted methacrylate 2i with diols 1b, 1f, 1j, and 1l forms α-exo-methylene-γ-butyrolactones 5b, 5f, 5j, and 5l in moderate to good yield. A catalytic cycle involving 1,2-dicarbonyl–acrylate oxidative coupling to form oxaruthenacyclic intermediates is postulated. A catalytically competent mononuclear ruthenium(II) complex was characterized by single-crystal X-ray diffraction. The influe...

Water Oxidation Catalyzed by Mononuclear Ruthenium Complexes with a 2,2′-Bipyridine-6,6′-dicarboxylate (bda) Ligand: How Ligand Environment Influences the Catalytic Behavior

A new water oxidation catalyst [Ru(III)(bda)(mmi)(OH2)](CF3SO3) (2, H2bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; mmi = 1,3-dimethylimidazolium-2-ylidene) containing an axial N-heterocyclic carbene ligand and one aqua ligand was synthesized and fully characterized. The kinetics of catalytic water oxidation by 2 were measured using stopped-flow technique, and key intermediates in the catalytic cycle were probed by density functional theory calculations. While analogous Ru-bda water oxidation catalysts [Ru(bda)L2] (L = pyridyl ligands) are supposed to catalyze water oxidation through a bimolecular coupling pathway, our study points out that 2, surprisingly, undergoes a single-site water nucleophilic attack (acid-base) pathway. The diversion of catalytic mechanisms is mainly ascribed to the different ligand environments, from nonaqua ligands to an aqua ligand. Findings in this work provide some critical proof for our previous hypothesis about how alternation of ancillary ligands of water oxidation catalysts influences their catalytic efficiency.

Water Oxidation by Mononuclear Ruthenium Complex with a Pentadentate Isoquinoline–Bipyridyl Ligand

AbstractMononuclear ruthenium complexes with a pentadentate ligand, N,N‐bis[(isoquinolin‐1‐yl)methyl][6‐(pyridin‐2‐yl)pyridin‐2‐yl]methanamine (DIQ‐Bpy), were synthesized and characterized by 1H NMR spectroscopy, elemental analysis, electrochemistry, and theoretical calculations. The oxidation of water by [Ru(DIQ‐Bpy)(H2O)]2+ was observed in the presence of excess amounts of CeIV. Relative to [Ru(DPA‐Bpy)(H2O)]2+ [DPA‐Bpy = N,N‐bis(2‐pyridinylmethyl)‐2,2′‐bipyridine‐6‐methanamine], the substitution of pyridine groups in DPA‐Bpy with electron‐withdrawing isoquinolines results in higher redox potential and lower activity for the oxidation of water by [Ru(DIQ‐Bpy)(H2O)]2+. A kinetic study of water oxidation by [Ru(DPA‐Bpy)(H2O)]2+ suggests a mononuclear pathway for the oxidation of water. The noncovalent interaction between isoquinoline groups in [Ru(DIQ‐Bpy)(H2O)]2+, which favors the formation of dinuclear species, might account for the lower activity for water oxidation by [Ru(DIQ‐Bpy)(H2O)]2+.

Computational and experimental study on the electrocatalytic reduction of CO2 to CO by a new mononuclear ruthenium(ii) complex.

A new mononuclear ruthenium(ii) complex, trans-[Ru(dmb)2(Cl)(EtOH)](PF6) (dmb = 4,4'-dimethyl-2,2'-bipyridine), has been prepared and characterized by elemental analysis, spectroscopic techniques and single crystal X-ray structure determination. The complex was studied as a precatalyst for the electrocatalytic reduction of CO2 to CO in an acetonitrile solution by cyclic voltammetry (CV). The catalytic mechanism was investigated by means of quantum chemical calculations to gain deeper insight into the process of CO2 reduction. The results suggest that the reaction proceeds in six steps initiating by the two sequential 1ē reductions at the dmb ligands followed by CO2 addition to give a metallocarboxylate intermediate. This intermediate undergoes further reduction and loses a CO molecule. The results reported in this paper are of great significance in providing theoretical insight into a class of electrocatalysts for reduction of CO2 to CO.

Cooperative effects in homogenous water oxidation catalysis by mononuclear ruthenium complexes

The homogenous water oxidation catalysis by [Ru(terpy)(bipy)Cl](+) (1) and [Ru(terpy)(Me2bipy)Cl](+) (2) (terpy = 2,2':6',2''-terpyridine, bipy = 2,2'-bipyridine, Me2bipy = 4,4'-dimethyl-2,2'-bipyridine) under the influence of two redox mediators [Ru(bipy)3](2+) (3) and [Ru(phen)2(Me2bipy)](2+) (4) (phen = 1,10-phenanthroline) was investigated using Ce(4+) as sacrificial oxidant. Oxygen evolution experiments revealed that mixtures of both 2-4 and 2-3 produced more molecular oxygen than catalyst 2 alone. In contrast, the combination of mediator 4 and catalyst 1 resulted in a lower catalytic performance of 1. Measurements of the temporal change in the intensity of a UV transition at 261 nm caused by the addition of four equivalents of Ce(4+) to 2 revealed three distinctive regions-suggested to correspond to the stepwise processes: (i) [Ru(IV)=O](2+) → [Ru(V)=O](3+); (ii) [Ru(V)=O](3+) → [Ru(III)-(OOH)](2+); and (iii) [Ru(III)-(OOH)](2+) → [Ru(II)-OH2](2+). UV-Visible spectrophotometric experiments on the 1-4 and 2-4 mixtures, also carried out with four equivalents of Ce(4+), demonstrated a faster [Ru(phen)2(Me2bipy)](3+) → [Ru(phen)2(Me2bipy)](2+) reduction rate in 2-4 than that observed for the 1-4 combination. Cyclic voltammetry data measured for the catalysts and the mixtures revealed a coincidence in the potentials of the Ru(II)/Ru(III) redox process of mediators 3 and 4 and the predicted [Ru(IV)=O](2+)/[Ru(V)=O](3+) potential of catalyst 2. In contrast, the [Ru(IV)=O](2+)/[Ru(V)=O](3+) process for catalyst 1 was found to occur at a higher potential than the Ru(II)/Ru(III) redox process for 4. Both the spectroscopic and electrochemical experiments provide evidence that the interplay between the mediator and the catalyst is an important determinant of the catalytic activity.

Studies on Ring-Opening Metathesis Polymerization of Norborene Catalyzed by Hydride Containing Mononuclear Ruthenium Complex

Ring-opening metathesis polymerization (ROMP) has emerged as an important tool for the preparation of architecturally unique macromolecules from cyclic olefins. A wide variety of catalytic systems, ranging from simple metal salts to highly sophisticated alkylidene metal complexes, have been used for the achievement of this synthetically useful transformation. Especially, tremendous efforts have been directed toward the ruthenium-based catalytic systems as well as the understanding of their reactivity patterns. And Grubbs catalysts represent the ultimate in terms of activity, but they are not cost effective due to the sophisticated ligand. Therefore, alternative catalyst precursors that are more readily accessible have been and are still being actively developed. Therefore, a hydride ligand containing mononuclear ruthenium complex Ru(p-cymene)HClPCy3 reported here was designed to catalyze ring-opening metathesis polymerization of norbornene with high activity. The hydride ligand is critical based on its high trans effect (for ligand dissociation) and the ability to generate carbene species through plausible migratory insertion and α-elimination steps. This catalytic system bearing hydride ligand could be an alternative for the well-defined Ru-based initiators which rules out the need of installation of complex ancillary ligands like NHC or O-Ligand in the coordination sphere or the need of activation with diazo compounds in the search for novel active catalytic species. Further study on the catalytic polymerization activity of Ru(p-cymene)H2PCy3 compared to the Ru(p-cymene)HClPCy3 system revealed that chloride ligand was also crucial to the hydride containing mononuclear ruthenium system, which contains easily dissociated ligand p-cymene and large phosphine ligand that stabilizes the metal complex. And the possible mechanism for the reaction was proposed.

Ruthenium-Catalyzed Hydrohydroxyalkylation of Acrylates with Diols and α-Hydroxycarbonyl Compounds To Form Spiro- and α-Methylene-γ-butyrolactones

Under the conditions of ruthenium(0)-catalyzed hydrohydroxyalkylation, vicinal diols 1a-1l and methyl acrylate 2a are converted to the corresponding lactones 3a-3l in good to excellent yield. The reactions of methyl acrylate 2a with hydrobenzoin 1f, benzoin didehydro-1f, and benzil tetradehydro-1f form the same lactone 3f product, demonstrating that this process may be deployed in a redox level-independent manner. A variety of substituted acrylic esters 2a-2h participate in spirolactone formation, as illustrated in the conversion of N-benzyl-3-hydroxyoxindole 1o to cycloadducts 4a-4h. Hydrohydroxyalkylation of hydroxyl-substituted methacrylate 2i with diols 1b, 1f, 1j, and 1l forms α-exo-methylene-γ-butyrolactones 5b, 5f, 5j, and 5l in moderate to good yield. A catalytic cycle involving 1,2-dicarbonyl-acrylate oxidative coupling to form oxaruthenacyclic intermediates is postulated. A catalytically competent mononuclear ruthenium(II) complex was characterized by single-crystal X-ray diffraction. The influence of electronic effects on regioselectivity in reactions of nonsymmetric diols was probed using para-substituted 1-phenyl-1,2-propanediols 1g, 1m, and 1n and density functional theory calculations.

Chemical and photocatalytic water oxidation by mononuclear Ru catalysts

Four mononuclear Ru complexes with different substituents on the para position of the pyridine ligand of Ru(bda)(pic) 2 (H 2 bda = 2,2′-bipyridine-6,6′-dicarboxylic acid; pic = picoline) were synthesized and characterized by 1 H nuclear magnetic resonance or X-ray crystallography. The electrochemical properties of this series of compounds in acidic and neutral conditions were studied by cyclic voltammetry. Their catalytic activity towards water oxidation was investigated using a chemical oxidant ([Ce(NH 4 ) 2 (NO 3 ) 6 ] (Ce IV ) in acidic solution, or driven by visible light in a three-component system containing a photosensitizer ([Ru(bpy) 3 ] 2+ ) and an electron acceptor (S 2 O 8 −2 ). For the chemical water oxidation, complex 1 was found to be the most effective, exhibiting a turnover number (TON) of up to 4000. The pyridine substituent at the 4-position in 1 may be protonated giving an intensive electron-withdrawing effect. Complex 2 bears the most electron-withdrawing trifluoromethyl group under neutral conditions and showed the highest photocatalytic activity with a TON of 270 over 2 h. It was concluded that the more electron-withdrawing substituents led to higher activity towards oxygen evolution for this type of Ru catalysts in the oxidation of water. Mononuclear ruthenium complexes based on the bipyridine-dicarboxylate (bda) ligand were prepared and showed high catalytic efficiencies for chemical and photochemical water oxidation, a key challenge for solar energy conversion into fuels. The more electron-withdrawing substituents on the axial ligands of the catalysts lead to higher activities towards water oxidation.

Visible light-driven water oxidation catalyzed by mononuclear ruthenium complexes

A series of mononuclear ruthenium water oxidation catalysts (WOCs) [Ru(bda)L2] (H2bda=2,2′-bipyridine-6,6′-dicarboxylic acid; L=N-cyclic aromatic ligands) were investigated in three-component light-driven water oxidation systems composed of photosensitizers, a sacrificial electron acceptor, and WOCs. A high turnover number of 579 for water oxidation was achieved in the homogeneous system using complex 4 ([Ru(bda)(4-Br-pyridine)2]) as the WOC, and a high quantum efficiency of 17% was found which is a new record for visible light-driven water oxidation in homogeneous systems.

Water‐Soluble Half‐Sandwich RuII–Arene Complexes: Synthesis, Structure, Electrochemistry, DFT Studies, and Aqueous Phase Hydroformylation of 1‐Octene

AbstractWater‐soluble mononuclear ruthenium complexes containing monodentate P‐donor ligands [1,3,5‐triaza‐7‐phosphaadamantane (PTA) and P(OMe)3], together with a mononuclear bidentate salicylaldimine ruthenium–arene complex, were synthesized from a water‐soluble dimeric ruthenium(II)–arene precursor. These complexes were used as catalyst precursors in the aqueous biphasic hydroformylation of 1‐octene. Hydroformylation reactions with these Ru‐arene complexes showed that the complexes are active hydroformylation catalyst precursors in water. The catalyst precursors convert 1‐octene into a range of products, which include aldehydes and alcohols, as well as isomerization and hydrogenation products. The less basic the ligand, the more it favoured the production of aldehydes. The relative basicity of the ligands P(OMe)3, PTA and the N,O‐chelating ligand was elucidated by cyclic voltammetry and supported by DFT calculations. The catalysts show good recyclability without a significant decrease in 1‐octene conversion. All of the catalysts could be reused three times.

An Electrochemical and Raman Spectroscopy Study of the Surface Behaviour of Mononuclear Ruthenium and Osmium Polypyridyl Complexes Based on Pyridyl‐ and Thiophene‐Based Linkers

AbstractThe utility of a thiophene anchor unit as an alternative for thiols in the immobilisation of ruthenium and osmium complexes on gold and platinum is examined with special attention focused on the relative contributions of physi‐ and chemisorption of the complexes and the chemical stability of the thiophene anchoring unit. The redox and spectroscopic properties of the ruthenium(II) and osmium(II) complexes are described in solution and the effect of surface immobilisation examined through a combined electrochemical and surface‐enhanced Raman spectroscopic study. A key finding is that although the thiophene unit is involved in surface anchoring it also undergoes chemical reactions with the gold surface as demonstrated by Raman spectroscopy.

Synthesis and structural characterization of asymmetric mononuclear ruthenium(II) complexes derived from 2-(1,2,3-thiadiazol-4-yl)pyridine and azoimine ligands

Five mononuclear ruthenium complexes of the general type trans-[RuII(L)(Azo)Cl2] {(Azo=C6H5NNC(COCH3)NC6H4Y, Y=H (1), CH3 (2), OCH3 (3), Cl (4), Br (5)} and L is 2-(1,2,3-thiadiazol-4-yl)pyridine have been synthesized and their structures investigated by elemental analyses, spectroscopic (IR, UV/–Vis, and NMR) and electrochemical (cyclic voltammetry) techniques. In addition, complex (3) has been further characterized by X-ray diffraction analysis. The absorption spectrum of 3 in acetonitrile has been modeled by time-dependent density functional theory (TD-DFT) using mixed basis set, LanL2DZ/6–-31+g(d,p), in acetonitrile as a solvent.

Structure and Electronic Configurations of the Intermediates of Water Oxidation in a Highly Active and Robust Molecular Ruthenium Catalyst

Photosynthesis is one of the most important chemical processes on our planet. Splitting water into O2 and H2 using sunlight is a clean and sustainable proposition for addressing energy and environmental problems encountered in our society. Mimicking this reaction in a manmade device will allow for sunlight-to-energy conversion with water providing electrons and protons for production of chemical fuels. About 30 years ago Meyer and coworkers reported the first ruthenium-based catalyst for water oxidation, known as the “blue dimer”. This catalyst may be considered as an artificial analog of the oxygen-evolving complex (OEC) in Photosystem II (PS II). Recently it has been demonstrated that single-site Ru and Ir catalysts are also active in water oxidation. These single-site catalysts are attractive model compounds for both experimental and theoretical studies of mechanism of water oxidation and show improved catalytic activity compared to “blue dimer”. A better understanding of this mechanism and identification of the rate-limiting steps could pave the way to light-driven generation of molecular hydrogen by water splitting.A mononuclear ruthenium complex [Ru(bda)(pic)2] (pic=4-picoline) was found to show high catalytic activity as well as high chemical stability. EPR, Raman and XAS characterization of the electronic structure and molecular geometry of Ru(III)-OH2,Ru(IV)=O and Ru(IV)-OO-Ru(IV) are reported in the single site water oxidizing complex. Formation of metal bound peroxides as the result of O-O coupling has been implicated in the mechanism of catalytic water oxidation by Photosystem II oxygen evolving complex (OEC) and in Ru-based catalysts. However, such intermediates were never isolated and their structural and electronic characterization has not been reported. We believe that the intermediates described here are direct products of the O-O bond formation step in the studied catalyst.

The preparation, characterisation and electronic structures of 2,4-pentadiynylnitrile (cyanobutadiynyl) complexes

Convenient preparative routes to mononuclear ruthenium complexes containing the 2,4-pentadiynylnitrile, or cyanobutadiynyl, ligand are described. The electronic properties of the [C(5)N](-) ligand are closely related to those of not only the cyanide ([CN](-)) and 2-propynylnitrile or cyanoacetylide ([C≡CC≡N](-)) ligands, but also those of the isoelectronic polyynyl ([{C≡C}(n)R](-)) ligands.

Highly efficient and robust molecular ruthenium catalysts for water oxidation

Water oxidation catalysts are essential components of light-driven water splitting systems, which could convert water to H(2) driven by solar radiation (H(2)O + hν → 1/2O(2) + H(2)). The oxidation of water (H(2)O → 1/2O(2) + 2H(+) + 2e(-)) provides protons and electrons for the production of dihydrogen (2H(+) + 2e(-) → H(2)), a clean-burning and high-capacity energy carrier. One of the obstacles now is the lack of effective and robust water oxidation catalysts. Aiming at developing robust molecular Ru-bda (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) water oxidation catalysts, we carried out density functional theory studies, correlated the robustness of catalysts against hydration with the highest occupied molecular orbital levels of a set of ligands, and successfully directed the synthesis of robust Ru-bda water oxidation catalysts. A series of mononuclear ruthenium complexes [Ru(bda)L(2)] (L = pyridazine, pyrimidine, and phthalazine) were subsequently synthesized and shown to effectively catalyze Ce(IV)-driven [Ce(IV) = Ce(NH(4))(2)(NO(3))(6)] water oxidation with high oxygen production rates up to 286 s(-1) and high turnover numbers up to 55,400.

Synthesis, spectroscopic characterization, antineoplastic, in vitro-cytotoxic, and antibacterial activities of mononuclear ruthenium(II) complexes

The synthesis, antineoplastic, cytotoxic, and antibacterial activities of Ru(II) complexes derived from quinazoline and thiosemicarbazone ligands are reported. These complexes have been prepared and characterized by UV-Vis, IR, 1H-NMR, FAB-mass spectroscopy, and elemental analysis. The ligands and resulting complexes were subjected to in vivo antineoplastic activity against a transplantable murine tumor cell line Ehrlich ascites carcinoma (EAC) and in vitro cytotoxic activity against human cancer cell line Molt 4/C8, CEM, and murine tumor cell line L 1210. The ruthenium complexes show promising biological activity especially in decreasing tumor volume and viable ascitic cell counts. These complexes prolonged the life span of mice bearing EAC tumors by 10–52%. In vitro evaluation of these ruthenium complexes revealed cytotoxic activity from 0.29 to 2.9 µmol L−1 against Molt 4/C8, 0.22 to 2.1 µmol L−1 against CEM and 0.42 to 4.7 µmol L−1 against L1210 cell proliferation, depending on the nature of the compound. The metal complexes are more active than the parent ligand and exhibit mild to moderate antibacterial activity.