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We report here on three new ruthenium(II) complexes, [Ru(DPEPhos)(mtz)(bipy)]PF 6 (Ru1), [Ru(DPEPhos)(mmi)(bipy)]PF 6 (Ru2) and [Ru(DPEPhos)(dmp)(bipy)]PF 6 (Ru3). DPEPhos = bis-[(2-diphenylphosphino)phenyl]ether, mtz = 2-mercapto-2-thiazoline, mmi = 2-mercapto-1-methylimidazole, dmp = 4,6-diamino-2-mercaptopyrimidine and bipy = 2,2'-bipyridine. The compounds were characterized by several spectroscopic techniques, and the molecular structure of Ru1 complex was determined by single-crystal X-ray diffraction. The cytotoxicity of Ru1 - Ru3 complexes were tested against the A549 (human lung) and the MDA-MB-231 (human breast) cancer cell lines and against MRC-5 (non-tumor lung) and MCF-10A (non-tumor breast) cell lines through the MTT assay. All three complexes are cytotoxic against the cell lines studied, with IC 50 values lower than those found for the cisplatin. Among them, the Ru2 complex has shown the best selectivity against MDA-MB-231 cancer cell lines, with an IC 50 value 12 times lower than that on MCF-10A. The complex Ru2 was capable to induce changes in MDA-MB-231 cells morphology, with loss of cellular adhesion, inhibited colony formation and induce an accumulation of cells at the sub-G1 phase, with an increase in S-phase and decrease of cells at G2 phase. Viscosity, electrochemical and Hoechst 33258 displacement experiments for Ru1 - Ru3 complexes with calf thymus DNA (CT-DNA) showed an electrostatic and groove binding mode of interaction. Additionally, the complexes interact with the protein Human Serum Albumin (HSA) by static mechanism. The negative values for ΔH and ΔS indicate that van der Waals forces and hydrogen bonding may occurs between the complexes and HSA. Therefore, this class of complexes are promising anticancer candidates and may be selected to further detailed studies., Competing Interests: Declaration of Competing Interest There are no conflicts to declare., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Five new complexes with general formula [Ru(L n )(PP)(bipy)]PF 6 , where L n  = N,N'-dimethyl-N-Acyl thiourea, and P-P: 1,2-bis(diphenylphosphino)ethane (dppe) or 1,4-bis(diphenylphosphino)butane (dppb)) were synthesized and characterized by elemental analysis, molar conductivity, cyclic voltammetry, IR, NMR ( 1 H, 13 C{ 1 H} and 31 P{ 1 H}), and single crystal X-ray diffractometry. The cytotoxicity of compounds against lung and breast tumor cell lines was significant, where two complexes, [Ru(L 3 )(bipy)(dppe)]PF 6 (3) and [Ru(L 3 )(bipy)(dppb)]PF 6 (6), were selected to evaluate changes in morphology, inhibition of migration and cell death in the MDA-MB-231 lineage. The complexes caused alterations in the cell morphology and were able to inhibit cell migration at the concentrations evaluated, induce the cell cycle arrested in the Sub-G1 phase, and induced cell death by apoptosis. All the complexes presented interaction with HSA, and the interaction studies with DNA suggested weak interactions, probably by the minor groove., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study, Ru(II)-arene complexes with acylthiourea ligands of the type [Ru(η 6 ‑p‑cymene)(PPh 3 )(T)Cl]PF 6 (1-5) and [Ru(η 6 ‑p‑cymene)(PPh 3 )(T)]PF 6 (1a, 4a), where PPh 3  = triphenylphosphine and T = N‑acyl‑N'(monosubstituted)thiourea, were synthesized and characterized, and their cytotoxic properties were also evaluated. 1a and 4a were obtained from the hydrolysis reaction of 1 and 4. All complexes showed unusual coordination modes for acylthiourea ligands, which are coordinated in a monodentate fashion (S) in 1-5, while they found to be bidentate (S,N), in 1a and 4a. To the best of our knowledge, 1a and 4a are the first crystallographically reported ruthenium compounds with acylthiourea coordinated via S and N(amide) atoms. The cytotoxicity of the compounds was evaluated in human lung cells, A549 and MRC-5. The IC 50 values ranging from 0.25 to 0.61 μM after 48 h incubation in lung cancer cells indicate that the compounds showed high cytotoxicity with values significantly lower than the reference drug, cisplatin (11.84 μM). Interaction studies were carried out using human serum albumin (HSA) and DNA. All complexes showed similar cytotoxic activity, however complex 1a, which is the hydrolysis product of 1, presented the highest activity and selectivity among all seven compounds synthesized here. Complexes 1 and 1a inhibited the colony formation decreasing the colony size and inducing morphology changes in A549 cells. These complexes induced apoptosis cell death and promoted cell cycle arrest in the Sub-G1 phase with a decrease in the cell number at the S phase., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Organometallic ruthenium complexes as potential anticancer agents have been explored due to their suitable properties, such as stability in the solid state and in solution, water solubility and low toxicity. In this study, eight metal complexes of this class were synthesized, characterized and their important biological activities against a human breast tumor cell line (MDA-MB-231) were studied. Complexes 1-8 were obtained in good yields and have been characterized by satisfactory elemental analyses, IR, 1D and 2D 1 H and 13 C{ 1 H} NMR, UV-Vis spectroscopy, cyclic voltammetry, ESI-MS and X-ray diffractometry (1, 2, 3 and 6). All complexes exhibit growth inhibition on human breast and lung tumor cell lines, with IC 50 values ranging from 6.0 to 45.0 μM in 48 h. Four compounds were selected to evaluate the changes in the morphology, clonogenic, migration, cell cycle arrest and cell death in MDA-MB-231 cells. The complexes are able to induce morphological changes and inhibit the size, number of colonies and cell migration, and induce cell cycle arrest in the sub-G1 phase and apoptosis cell death. The interaction of the complexes with DNA was determined by performing spectroscopic titration, a competitive assay with thiazole orange, circular dichroism, gel electrophoresis and interactions with guanosine or guanosine monophosphate by 1 H NMR, indicating the non-covalent interaction. The HSA binding affinity measured by spectrophotometric titration, revealed the hydrophobic and spontaneous association with the human protein. Overall, the studies indicated that these metal complexes are potential agents against MDA-MB-231 cells, encouraging us to continue studies of these types of compounds.

Four ruthenium(II)-based complexes with N-(acyl)-N',N'-(disubstituted)thiourea derivatives (Th) were obtained. The compounds, with the general formula trans-[Ru(PPh3)2(Th)(bipy)]PF6, interact with bovine serum albumin (BSA) and DNA. BSA-binding constants, which were in the range of 3.3-6.5×10(4) M(-1), and the thermodynamic parameters (ΔG, ΔH and ΔS), suggest spontaneous interactions with this protein by electrostatic forces due to the positive charge of the complexes. Also, binding constant by spectrophotometric DNA titration (Kb = 0.8-1.8×10(4) M(-1)) and viscosity studies indicate weak interactions between the complexes and DNA. Cytotoxicity assays against DU-145 (prostate cancer) and A549 (lung cancer) tumour cells revealed that the complexes are more active in tumour cells than in normal (L929) cells, and that they present high cytotoxicity (low IC50 values) compared with the reference metallodrug, cisplatin., (Copyright © 2015. Published by Elsevier Inc.)

Complexes [RuCl(H4NO(2)Fo4M)(bipy)(dppb)]PF(6) (1), [RuCl(H4NO(2)Fo4M)(Mebipy)(dppb)]PF(6) (2), [RuCl(H4NO(2)Fo4M)(phen)(dppb)]PF(6) (3), [RuCl(H4NO(2)Ac4M)(bipy)(dppb)]PF(6) (4), [RuCl(H4NO(2)Ac4M)(Mebipy)(dppb)]PF(6) (5) and [RuCl(H4NO(2)Ac4M)(phen)(dppb)]PF(6) (6) with N(4)-methyl-4-nitrobenzaldehyde thiosemicarbazone (H4NO(2)Fo4M) and N(4)-methyl-4-nitroacetophenone thiosemicarbazone (H4NO(2)Ac4M) were obtained from [RuCl(2)(bipy)(dppb)], [RuCl(2)(Mebipy)(dppb)], and [RuCl(2)(phen)(dppb)], (dppb = 1,4-bis(diphenylphospine)butane; bipy = 2,2'-bipyridine; Mebipy = 4,4'-dimethyl-2,2'-bipyridine; phen = 1,10-phenanthroline). In all cases the thiosemicarbazone is attached to the metal center through the sulfur atom. Complexes (1-6), together with the corresponding ligands and the Ru precursors were evaluated for their ability to in vitro suppress the growth of Trypanosoma cruzi. All complexes were more active than their corresponding ligands and precursors. Complexes (1-3) and (5) revealed to be the most active among all studied compounds with ID(50) = 0.6-0.8 microM. In all cases the association of the thiosemicarbazone with ruthenium, dppb and bipyridine or phenanthroline in one same complex proved to be an excellent strategy for activity improvement., (Copyright (c) 2010 Elsevier Masson SAS. All rights reserved.)

Three novel polymetallic ruthenium (III) meso-tetra(4-pyridyl)porphyrins containing peripheral "RuCl(3)(dppb)" moieties have been prepared and characterized. The X-ray structure of the tetraruthenated {NiTPyP[RuCl(3)(dppb)](4)} porphyrin complex crystallizes in the triclinic space group P1. This structure is discussed and compared with the crystal data for the mer-[RuCl(3)(dppb)(py)]. The {TPyP[RuCl(3)(dppb)](4)} and {CoTPyP[RuCl(3)(dppb)](4)} porphyrins were used to obtain electrogenerated films on ITO and glass carbon electrode surfaces, respectively. Such tetraruthenated porphyrins form films of a mixed-valence species {TPyP[Ru(dppb)](4)(muCl(3))(2)}(2n)(4n2+) and {CoTPyP[Ru(dppb)](4)(muCl(3))(2)}(2n)(4n2+) on the electrode surface. The modified electrode with {CoTPyP[RuCl(3)(dppb)](4)} is very stable and can be used to detect organic substrates such as catechol.

The reaction of cis-[RuCl(2)(dppb)(N-N)], dppb=1,4-bis(diphenylphosphino)butane, complexes with the ligand HSpymMe(2), 4,6-dimethyl-2-mercaptopyrimidine, yielded the cationic complexes [Ru(SpymMe(2))(dppb)(N-N)]PF(6), N-N=bipy (1) and Me-bipy (2), bipy=2,2'-bipyridine and Me-bipy=4,4'-dimethyl-2,2'-bipyridine, which were characterized by spectroscopic and electrochemical techniques and X-ray crystallography and elemental analysis. Additionally, preliminary in vitro tests for antimycobacterial activity against Mycobacterium tuberculosis H37Rv ATCC 27264 and antitumor activity against the MDA-MB-231 human breast tumor cell line were carried out on the new complexes and also on the precursors cis-[RuCl(2)(dppb)(N-N)], N-N=bipy (3) and Me-bipy (4) and the free ligands dppb, bipy, Me-bipy and SpymMe(2). The minimal inhibitory concentration (MIC) of compounds needed to kill 90% of mycobacterial cells and the IC(50) values for the antitumor activity were determined. Compounds 1-4 exhibited good in vitro activity against M. tuberculosis, with MIC values ranging between 0.78 and 6.25microg/mL, compared to the free ligands (MIC of 25 to >50microg/mL) and the drugs used to treat tuberculosis. Complexes 1 and 2 also showed promising antitumor activity, with IC(50) values of 0.46+/-0.02 and 0.43+/-0.08microM, respectively, against MDA-MB-231 breast tumor cells.

The [Ru(II)(Hedta)NO(+)] complex is a diamagnetic species crystallizing in a distorted octahedral geometry, with the Ru-N(O) length 1.756(4) A and the RuNO angle 172.3(4) degrees . The complex contains one protonated carboxylate (pK(a)=2.7+/-0.1). The [Ru(II)(Hedta)NO(+)] complex undergoes a nitrosyl-centered one-electron reduction (chemical or electrochemical), with E(NO+/NO)=-0.31 V vs SCE (I=0.2 M, pH 1), yielding [Ru(II)(Hedta)NO](-), which aquates slowly: k(-NO)=2.1+/-0.4x10(-3) s(-1) (pH 1.0, I=0.2 M, CF(3)COOH/NaCF(3)COO, 25 degrees C). At pHs>12, the predominant species, [Ru(II)(edta)NO](-), reacts according to [Ru(II)(edta)NO](-)+2OH(-)-->[Ru(II)(edta)NO(2)](3-), with K(eq)=1.0+/-0.4 x 10(3) M(-2) (I=1.0 M, NaCl; T=25.0+/-0.1 degrees C). The rate-law is first order in each of the reactants for most reaction conditions, with k(OH(-))=4.35+/-0.02 M(-1)s(-1) (25.0 degrees C), assignable mechanistically to the elementary step comprising the attack of one OH(-) on [Ru(II)(edta)NO](-), with subsequent fast deprotonation of the [Ru(II)(edta)NO(2)H](2-) intermediate. The activation parameters were DeltaH(#)=60+/-1 kJ/mol, DeltaS(#)=-31+/-3 J/Kmol, consistent with a nucleophilic addition process between likely charged ions. In the toxicity up-and-down tests performed with Swiss mice, no death was observed in all the doses administered (3-9.08 x 10(-5) mol/kg). The biodistribution tests performed with Wistar male rats showed metal in the liver, kidney, urine and plasma. Eight hours after the injection no metal was detected in the samples. The vasodilator effect of [Ru(II)(edta)NO](-) was studied in aortic rings without endothelium, and was compared with sodium nitroprusside (SNP). The times of maximal effects of [Ru(II)(edta)NO](-) and SNP were 2 h and 12 min, respectively, suggesting that [Ru(II)(edta)NO](-) releases NO slowly to the medium in comparison with SNP.

We have synthesized and characterized three new ruthenium(II) diphosphine complexes containing an acylthiourea ligand, with the general formula [Ru(DPEPhos)(O,S)(bipy)]PF6, where DPEPhos = bis(2-(diphenylphosphino)phenyl)ether, bipy = 2,2′-bipyridine, and O,S = N,N-dimethyl-N′-(benzoyl)thiourea (1), N,N-dimethyl-N′-(furoyl)thiourea (2), and N,N-dimethyl-N′-(thiophenyl)thiourea (3), by several physicochemical techniques. We evaluated the ruthenium complexes for their cytotoxicity against two human cancer cell lines, A549 (lung) and MDA-MB-231 (breast), and two corresponding lines of non-cancer cells, MRC-5 (lung) and MCF-10A (breast). All the complexes are cytotoxic against the cancer cell lines; the IC50 values lie in the micromolar range (0.07–0.70 μM). Ruthenium complex 1 is more selective (7 times more active) toward lung cancer cells (A549) than toward non-cancer cells (MRC-5) and is 160 times more cytotoxic than cisplatin against A549 cells. Investigations of the mechanism of action of complex 1 in A549 cells demonstrated that it inhibits colony formation and promotes cell cycle arrest in the G1 phase and apoptotic cell death. DNA binding studies revealed that complexes 1–3 interact with the biomolecule via minor grooves. These complexes also interact with human serum albumin (HSA) and have affinity for site I by hydrophobic forces. Therefore, this new class of ruthenium complexes can act as cytotoxic agents, mainly for lung cancer treatment. [ABSTRACT FROM AUTHOR]

This manuscript describes the preparation of a new Ru(ii) nitrosylsulphito complex, trans-[Ru(NH3)4(isn)(N(O)SO3)]+ (complex 1), its spectroscopic and structural characterization, photochemistry, and thermal reactivity. Complex 1 was obtained by the reaction of sulfite ions (SO32−) with the nitrosyl complex trans-[Ru(NH3)4(isn)(NO)]3+ (complex 2) in aqueous solution resulting in the formation of the N-bonded nitrosylsulphito (N(O)SO3) ligand. To the best of our knowledge, only four nitrosylsulphito metal complexes have been described so far (J. Chem. Soc., Dalton Trans., 1983, 2465–2472), and there is no information about the photochemistry of such complexes. Complex 1 was characterized by spectroscopic means (UV-Vis, EPR, FT-IR, 1H- and 15N-NMR), elemental analysis and single-crystal X-ray diffraction. The X-ray structure of the precursor complex 2 is also discussed in the manuscript and is used as a reference for comparisons with the structure of 1. Complex 1 is water-soluble and kinetically stable at pH 7.4, with a first-order rate constant of 3.1 × 10−5 s−1 for isn labilization at 298 K (t1/2∼ 373 min). Under acidic conditions (1.0 M trifluoroacetic acid), 1 is stoichiometrically converted into the precursor complex 2. The reaction of hydroxide ions (OH−) with 1 and with 2 yields the Ru(ii) nitro complex trans-[Ru(NH3)4(isn)(NO2)]+ with second-order rate constants of 2.1 and 10.5 M−1 s−1 (at 288 K), respectively, showing the nucleophilic attack of OH− at the nitrosyl in 2 (Ru–NO) and at the nitrosylsulphito in 1 (Ru–N(O)SO3). The pKa value of the –SO3 moiety of the N(O)SO3 ligand in 1 was determined to be 5.08 ± 0.06 (at 298 K). The unprecedented photochemistry of a nitrosylsulphito complex is investigated in detail with 1. The proposed mechanism is based on experimental (UV-Vis, EPR, NMR and Transient Absorption Laser Flash Photolysis) and theoretical data (DFT) and involves photorelease of the N(O)SO3− ligand followed by formation of nitric oxide (NOṖ) and sulfite radicals (SO3Ṗ−, sulfur trioxide anion radical). [ABSTRACT FROM AUTHOR]

Here, we report the synthesis, characterization, crystal data and DFT calculation of a new water-soluble ruthenium(II) carbonyl complex. The trans -[Ru(CO)(NH 3 ) 4 P(O)(OH) 2 ]Cl is a robust complex in aqueous media. The p K a of 3.3 for the phosphorous acid ligand in this complex was measured by infrared spectroscopy. The trans -[Ru(CO)(NH 3 ) 4 P(O)(OH) 2 ] + exhibits just two slow reactions at pH 7.5: CO–Ru–P(O)(OH) 2 to CO–Ru–(O)P(OH) 2 isomerization ( k = 1.1 × 10 −5 s −1 at 25 °C) and subsequent P(O)(OH) 2 dissociation ( k = 1.7 × 10 −7 s −1 at 25 °C). The formation of O-bonded trans -[Ru(CO)(NH 3 ) 4 (O)P(OH) 2 ] + was supported by IR, UV–Vis and 31 P NMR spectroscopies and DFT calculations. [ABSTRACT FROM AUTHOR]

The complex fac-[Ru(NO)Cl2(κ³N4,N8,N11 (1-carboxypropyl)cyclam)]Cl · H2O (1-carboxypropyl)cyclam = 3-(1,4,8,11-tetraazacyclotetradecan-1-yI)propionic acid) was prepared in a one pot reaction by mixing equimolar amounts of RuNOCl3 and (1-carboxypropyl)cyclam and was characterized by X-ray crystallography, electrospray ionization tandem mass spectrometry (ESI-MS/MS), elemental analysis, NMR, and electronic and vibrational (IR) spectroscopies. fac-[Ru(NO)Cl2(κ³N4,N8,N11(1-carboxypropyl)cyclam)]Cl · H2O crystallizes in the triclinic, space group P1, No. 2, with unit cell parameters of a = 8.501 (1) Å, b = 9.157(1) Å, c = 14.200(1) Å, α = 72.564(5)°, β = 82.512(5)°, ³ = 80.308(5)°, and Z = 2. The Ru-N interatomic distance and bond angle in the [Ru-NO] unit are 1.739(2) Å and 167.7(2)°, respectively. ESI-MS/MS shows characteristic dissociation chemistry that initiates by HCl or NO loss. The IR spectrum displays a ν(NO) at 1881 cm-1 indicating a nitrosonium character. The electronic spectrum shows absorptions bands at 264 nm (log ε = 3.27), 404 nm (log ε = 2.53), and 532 nm (log ε = 1.88). ¹H and 13C NMR are in agreement with the proposed molecular structure, which shows a very singular architecture where the cyclam ring N (with the carboxypropyl pendant arm) is not coordinated to the ruthenium resulting in a κ³ instead of the expected κ4 denticity. [ABSTRACT FROM AUTHOR]

In this work a series of {[RuCl 2 (dppb)](μ-4,4′-N-N)} 4 complexes were synthesized and characterized by elemental analysis, cyclic voltammetry and differential pulse voltammetry and UV-Vis and 31 P{ 1 H} NMR spectroscopies; [(μ-4,4′-N-N=pyrazine (pz), 4,4′-bipyridine=(4,4′-bipy), 1,2-bis- trans -(4-pyridyl)ethane = (pyeta) and 1,2-bis- trans -(4-pyridyl)ethylene=(pyetil) as bridging alterdentate ligands (alterdentate ligands are molecules (or ions), with two equivalent ligating atoms or ligating sites that do not simultaneously bind to a metallic center [Zelewsky von A. in Stereochemistry of Coordination Compounds , Inorganic Chemistry , A Textbook Series; John Wiley & Sons, Inc.: New York, 1995: p. 45] [1] ) and 1,4-bis(diphenylphosphino)butane=dppb]. Electrochemical experiments (cyclic voltammetry and differential pulse voltammetry) suggest that for longer ligands the interaction between two ruthenium atoms is weak and for short ligands like pyrazine the corresponding interaction is strong. The analysis of the X-ray structure of the {[RuCl 2 (dppb)](μ-4,4′-bipy)} 4 complex showed that the molecular squares obtained are stacked on top of each other along the α axis forming infinite columns and that the formation of central tunnels is prevented by the bulky character of the phenyl groups of the diphenylphosphine ligands. [ABSTRACT FROM AUTHOR]

The crystal structure of [Ru(NH3)5(OH2)]2(S2O6)3 · 2H2O has been solved by X-ray diffraction techniques. The relevant average interatomic distances are Ru–(NH3)eq=2.09 A˚, Ru–(NH3)ax=2.08 A˚ and Ru–(OH2)ax=2.11 A˚. The aquation rate (kH2O) and the activation parameters for the reactiontrans-[RuNO(NH3)4Cl]2++H2O→, upper limit kH2O trans-[RuNO(NH3)4(H2O)]3++Cl−have been calculated as 8.4 × 10−6 s−1 (0.10 mol L−1 CF3COOH, μ=0.10 mol L−1, 40 °C), ΔH≠−1=2.3 kcal mol−1, ΔS≠−1=24.0 cal deg−1 mol and ΔG≠−1=8.6 kcal mol−1. A comparison between the structural data, kinetic and thermodynamic reactivities of [Ru(NH3)5(OH2)]3+ and trans-[RuNO(NH3)4(OH2)]3+ ions strongly suggests that the substitution of the trans NH3 ligand in the coordination sphere of [Ru(NH3)5(OH2)]2+ by NO confers a character of Ru(III) to the formally Ru(II) center. [Copyright &y& Elsevier]

Highlights an experimental study which developed a route for the preparation of trans nitrosyl complexes of the formula [Ru-(NH3)4L(NO)](BF4)3. In-depth look at the synthesis of the complexes; Analysis of ruthenium (Ru); Information on the X-ray crystallography of the complexes; What the results of the study showed.

Complexes with the general formula [Ru(dppb)(R) 2 ] {where: dppb = 1,4-bis(diphenylphosphino)butane and R = piperidinedithiocarbamate (pipeCS 2 − ) ( 1 ); morpholinedithiocarbamate (morphCS 2 − ) ( 2 ); ethilenodiaminedithiocarbamate (ethCS 2 − ) ( 3 ) and hexamethilenominedithiocarbamate (hexCS 2 − ) ( 4 )} were synthesised from [RuCl 2 (dppb)] 2 -μ-(dppb). The complexes were characterised by nuclear magnetic resonance of phosphorus ( 31 P{ 1 H} NMR), cyclic voltammetry (CV) as well as elemental analyses. The X-ray structures of ( 1 ), ( 2 ), and ( 3 ) were determined and are presented here. Additionally, the complexes ( 1 – 4 ) were used as pre-catalysts in the epoxidation of cyclooctene, and initial results show that complex ( 4 ) has a selectivity of 74% in the epoxide product, with 53% conversion. The epoxidation catalysed used iodosylbenzene (PhIO) as primary oxidant. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and characterization of ruthenium compounds of the type [RuCl2(NO)(dppp)(L)]PF6 [dppp=1,3-bis(diphenylphosphino)propane; L=pyridine, 4-methylpyridine, 4-phenylpyridine and dimethyl sulfoxide] are described. The complexes were characterized by elemental analysis, UV/Vis and infrared spectroscopy, cyclic voltammetry, and X-ray crystallography for the complexes with the pyridine and 4-methylpyridine ligands. In vitro evaluation of these nitrosyl complexes revealed cytotoxic activity from 7.1 to 19.0μM against the MDA-MB-231 breast tumor cells and showed that, in this case, they are more active than the reference metallodrug cisplatin. The 1,3-bis(diphenylphosphino)propane and the N-heterocyclic ligands alone failed to show cytotoxic activities at the concentrations tested (maximum concentration utilized=200μM). [Copyright &y& Elsevier]

Abstract: The chemistry of Ru(III) complexes containing dmso as a ligand has become an interesting area in the cancer treatment field. Because of this, structural knowledge and chemistry of the moiety Ru(III)–dmso have become important to cancer research. The crystal structures of the compounds mer-[RuCl3(dms)3] (1) and mer-[RuCl3(dms)2(dmso)]:mer-[RuCl3(dms)3] (2) were determined by X-ray crystallography and a speciation of the presence of intramolecular hydrogen bond in these structures has been studied. Compound (1) crystallizes in the orthorhombic space group, Pna21; a =16.591(8)Å, b =8.724(2)Å, c =10.547(3)Å; Z =12 and (2) crystallizes in the space group, P21/C; a =11.9930(2)Å, b =7.9390(2) Å, c =15.8700(3)Å, β =93.266(1)°, Z =2. From the X-ray structures solved in this work, were possible to suggest an interpretation for the broad lines observed in the EPR spectra of the Ru(III) compounds explored here. Also, the exchange interactions detected by EPR spectroscopy in solid state and in solution, confirm the presence of van der Waals interactions such as C–H…Cl in the compounds (1), (2) and (3). The use of techniques such as IR, UV–vis, 1H NMR and EPR Spectroscopy and Cyclic Voltammetry were applied in this work to analyze the behavior of these metallocompounds. [Copyright &y& Elsevier]

Abstract: [Ru(HL)(PPh3)2Cl]Cl complexes have been obtained in which HL= N(4)-ortho (complex 1), N(4)-meta (complex 2) and N(4)-para-tolyl 2-acetylpyridine thiosemicarbazone (complex 3). NMR and electrochemical studies indicate that both cis and trans isomers exist in solution, and that the cis isomers are converted into the trans isomers with time. Crystal structure determination of (1) reveals that the trans isomer is formed in the solid state. [Copyright &y& Elsevier]

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]

Abstract: The reaction of RuCl3NO·2H2O with stoichiometric amount of dppf, 1,1′-bis(diphenylphosphino)ferrocene, afforded the new neutral nitrosyl complex fac-[RuCl3(NO)(dppf)] which was characterized by spectroscopical, electrochemical and X-ray crystallography techniques as well as elemental analysis. The ν NO band in the IR spectrum is at 1860cm−1 (CH2Cl2 solution) and in the cyclic voltammogram an irreversible wave was observed at −1.35V, both are characteristics of a nitrosonium (NO+) character for the coordinated NO. Additionally, preliminary in vitro antitumor activity against the MDA-MB-231 breast tumor cell line was carried out for the new complex. The initial results indicated an important activity for fac-[RuCl3(NO)(dppf)] (IC50 =10±3μM ). The complex has a higher cytotoxicity than the precursor complex RuCl3NO·2H2O, the free dppf ligand as well as the reference metallodrug cisplatin. [Copyright &y& Elsevier]

Abstract: The trans-[RuCl2(dppb)(1,4-dt)], mer-[RuCl3(dppb)(1,4-dt)] and [{RuCl3(dppb)}2(μ-(1,4-dt))] complexes were synthesized and characterized by spectroscopic and electrochemical techniques. Despite the favorable energy for the C 2h conformation, the crystallographic data point for the 1,4-dithiane (1,4-dt) D2 conformer in the trans-[RuCl2(dppb)(1,4-dt)] complex, where it acts as a bidentate ligand. The E 1/2 value of this complex is higher than those found for some related pyridine derivative compounds showing that with this thio-ligand, the Ru(II) atom presents a relatively strong π back-bonding interaction. Apart from the phosphine intraligand transitions, the UV/Vis spectrum of the trans-[RuCl2(dppb)(1,4-dt)] complex shows only one band at 457nm assigned to the MLCT transition. The bands observed in the spectra of the mer-[RuCl3(dppb)(1,4-dt)] and [{RuCl3(dppb)}2(μ-(1,4-dt))] complexes, at 530, 420 and 347nm were attributed to the contribution of the (RuIII)←(Cl,S) LMCT transitions. The EPR spectrum of the mer-[RuCl3(dppb)(1,4-dt)] complex shows three g-values in 2.87, 2.15 and 1.73, suggesting that the 1,4-dt is coordinated in a monodentate mode. The NMR, EPR, FTIR and crystallographic data point for the ruthenium-phosphine species as the first example of metallic system that form complexes with the 1,4-dithiane acting as bidentate, monodentate and bridged ligand. [Copyright &y& Elsevier]

Abstract: The [Ru(dppb)(mbt)2], mbt=2-mercaptobenzothiazole, complex, isolated from the reaction of the mer-[RuCl3(dppb)(OH2)] complex with the 2,2′-dithiobis(benzothiazole), mbts, was characterized by spectroscopic and electrochemical techniques (E 1/2 =0.78V versus NHE) and its structure was determined by crystal X-ray analysis. The structural analysis suggests that the S–S bond of the mbts ligand is cleaved, thus forming two four-membered chelate rings coordinated to the ruthenium through the N,S-donor atoms of the mbt reduced ligands, with an average bite angle of 67.295(11)°. The 1H and 13C NMR signals observed for mbts ligand coordinated to the metal center, the changes in the vibrational spectra, and the appearance of a MLCT band in the electronic spectrum of the complex point for the reduced state of the ruthenium metal center, RuII. These reducing processes are suggested to be due to the methanol interference, which is observed to be strongly affected by N-methylmorpholine. The cytochrome c electrochemistry was analyzed by using the SAMs formed by the mbts and the [Ru(dppb)(mbt)2] complex on gold, with only the former presenting electroactivity. [Copyright &y& Elsevier]

Abstract: Ruthenium (II) complexes with the hemilabile ligand Ph2PCH2P(O)Ph2 (dppmO) were obtained and characterized by 31P{1H} NMR, IR and cyclic voltammetry. The reaction of the compound tcc-[RuCl2(η2-dppmO)2] with carbon monoxide yielded the complexes [RuCl2(CO)(η1,η2-dppmO)2] and [RuCl(CO)(η2-dppmO)2]PF6. For the tcc-[RuCl2(η2-dppmO)2] and [RuCl2(CO)(η1,η2-dppmO)2] species, two dimensional NMR analyses 31P–31P gCOSY, 13C–1H HSQC, 1H–31P HMBC were performed. Based on the resulting chemical shifts, coupling constants and correlations between 1H, 13C and 31P spectra it was possible to reveal the structures of these complexes in solution. The structure of the tcc-[RuCl2(η2-dppmO)2] complex was determined by X-ray diffraction, confirming the NMR results. The mer-[RuCl3(η1,η2-dppmO)2] complex was characterized by EPR and its crystal structure was also established by X-ray diffraction. The isomerization of tcc-[RuCl2(η2-dppmO)2] into cct-[RuCl2(η2-dppmO)2] was followed by UV–Vis spectroscopy and 31P{1H} NMR. [Copyright &y& Elsevier]

The [RuII(Hedta)NO+] complex is a diamagnetic species crystallizing in a distorted octahedral geometry, with the Ru–N(O) length 1.756(4) Å and the RuNO angle 172.3(4)°. The complex contains one protonated carboxylate (pKa=2.7±0.1). The [RuII(Hedta)NO+] complex undergoes a nitrosyl-centered one-electron reduction (chemical or electrochemical), with ENO+/NO=−0.31 V vs SCE (I=0.2 M, pH 1), yielding [RuII(Hedta)NO]−, which aquates slowly: k–NO=2.1±0.4×10−3 s−1 (pH 1.0, I=0.2 M, CF3COOH/NaCF3COO, 25 °C). At pHs>12, the predominant species, [RuII(edta)NO]−, reacts according to [RuII(edta)NO]−+2OH−⇒[RuII(edta)NO2]3−, with Keq=1.0±0.4×103 M−2 (I=1.0 M, NaCl; T=25.0±0.1 °C). The rate-law is first order in each of the reactants for most reaction conditions, with kOH−=4.35±0.02 M−1s−1 (25.0 °C), assignable mechanistically to the elementary step comprising the attack of one OH− on [RuII(edta)NO]−, with subsequent fast deprotonation of the [RuII(edta)NO2H]2− intermediate. The activation parameters were ΔH#=60±1 kJ/mol, ΔS#=−31±3 J/Kmol, consistent with a nucleophilic addition process between likely charged ions. In the toxicity up-and-down tests performed with Swiss mice, no death was observed in all the doses administered (3–9.08×10−5 mol/kg). The biodistribution tests performed with Wistar male rats showed metal in the liver, kidney, urine and plasma. Eight hours after the injection no metal was detected in the samples. The vasodilator effect of [RuII(edta)NO]− was studied in aortic rings without endothelium, and was compared with sodium nitroprusside (SNP). The times of maximal effects of [RuII(edta)NO]− and SNP were 2 h and 12 min, respectively, suggesting that [RuII(edta)NO]− releases NO slowly to the medium in comparison with SNP. [Copyright &y& Elsevier]

The present paper describes a new tripodal ligand containing imidazole and pyridine arms and its first cis-[RuIII(L)(Cl)2]ClO4 complex (1). The crystal structure of 1 shows RuIII in a distorted octahedral geometry, in which two chloride ions, cis-positioned to each other, are coordinated besides the four nitrogen atoms from the tetradentate ligand L. The cyclic voltammogram of 1 exhibits three redox processes at −67, +73 and +200 mV versus SCE, which are attributed to the RuIII/RuII couple in the cis-[RuIII(L)(Cl)2]+, cis-[RuII(L)(H2O)(Cl)]+ and cis-[RuII(L)(H2O)2]2+, respectively. After chemical reduction (Zn(Hg) or EuII) only the cis-[RuII(L)(H2O)2]2+ species is observed in the cyclic voltammetry. Complex 1 absorbs at 470 nm (ϵ=1.4×103 mol−1 L cm−1), 335 nm (ϵ=7.9×103 mol−1 L cm−1), 301 nm (ϵ=6.7×103 mol−1 L cm−1) and 264 nm (ϵ=9.9×103 mol−1 L cm−1), in water solution (CF3COOH, 0.01 mol L−1, μ=0.1 mol L−1 with CF3COONa). Spectroelectrochemical experiments show a decrease of the bands at 335 and 301 nm, which are attributed to LMCT transitions from the chloride to the RuIII center and the appearance of a broad band at 402 nm ascribed to MLCT transition from the RuII center to the pyridine ligand. The lability of the water ligands in the cis-[RuII(L)(H2O)2]2+ species has been investigated using the auxiliary ligand pyrazine. Reactions in the presence of stoichiometric and excess of pyrazine yield the same species, cis-[RuII(L)(H2O)(pz)]2+, which exhibits a reversible redox process at 493 mV versus SCE and absorbs at 438 nm (ϵ=5.1×103 mol−1 L cm−1) and 394 nm (ϵ=4.2×103 mol−1 L cm−1). Experiments performed with a large excess of pyrazine gave a specific rate constant k1=(2.8±0.5)×10−2 M−1 s−1, at 25 °C, in CF3COOH, 0.01 mol L−1, μ=0.1 mol L−1 (with CF3COONa). [Copyright &y& Elsevier]

Trans-[RuCl(NO)(dppe)2]2+ species were prepared. The complexes have been characterized by microanalysis, IR and 31P{1H} NMR spectroscopy and cyclic voltammetry. The trans-[RuCl(NO)(dppe)2](ClO4)2 complex shows a reversible one-electron-reduction process at E1/2 = 0.200 V and another one-electron-reduction irreversible process at −0.620 V, both centered at the NO+ group. The dissociation of the NO group from the trans-[RuCl(NO)(dppe)2]2+ after two one-electron reductions results in the formation of the trans- and cis-[RuCl2(dppe)2] isomers. The product of an electrolyzed solution of the same complex at −0.300 V shows an EPR signal consistent with the presence of the [RuCl(NO0)(dppe)2]+ complex. Crystal data for trans-[RuCl(NO)(dppe)2]2+·[RuCl4(NO)(H2O)]·1/2[RuCl6]4−·2[H2O] (I) and trans-[RuCl(NO)(dppe)2]2+·2[RuCl4(NO)(CH3O)]−·3[CH3OH] (II) are as follow: (I) Space group P-1, a=10.4040(3) A˚, b=12.3470(4) A˚, c=23.5620(8) A˚, α=95.885(2)°, β=99.608(2)°, γ=104.378(2)°, R=0.0521; (II) space group P-1, a=10.9769(2) A˚, b=13.2753(3) A˚, c=24.0287(4) A˚, α=99.743(1)°, β=95.847(1)°, γ=97.549(1)°; R=0.0496. The fac-[RuCl3(NO)(dppe)] (III) complex has been also prepared; its crystal data are: space group P21/n (No. 14), a=11.841(2) A˚, b=13.775(2) A˚, c=16.295(4) A˚, β=92.81(2)°; R1=0.0395. [Copyright &y& Elsevier]