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Upon exploration of the chemistry of the combination of ruthenium/arene with anthraquinone alizarin (L), three new complexes with the general formulas [Ru(L)Cl(η 6 - p -cymene)] ( C1 ), [Ru(L)(η 6 - p -cymene)(PPh 3 )]PF 6 ( C2 ), and [Ru(L)(η 6 - p -cymene)(PEt 3 )]PF 6 ( C3 ) were synthesized and characterized using spectroscopic techniques (mass, IR, and 1D and 2D NMR), molar conductivity, elemental analysis, and X-ray diffraction. Complex C1 exhibited fluorescence, such as free alizarin, while in C2 and C3 , the emission was probably quenched by monophosphines and the crystallographic data showed that hydrophobic interactions are predominant in intermolecular contacts. The cytotoxicity of the complexes was evaluated in the MDA-MB-231 (triple-negative breast cancer), MCF-7 (breast cancer), and A549 (lung) tumor cell lines and MCF-10A (breast) and MRC-5 (lung) nontumor cell lines. Complexes C1 and C2 were more selective to the breast tumor cell lines, and C2 was the most cytotoxic (IC 50 = 6.5 μM for MDA-MB-231). In addition, compound C1 performs a covalent interaction with DNA, while C2 and C3 present only weak interactions; however, internalization studies by flow cytometry and confocal microscopy showed that complex C1 does not accumulate in viable MDA-MB-231 cells and is detected in the cytoplasm only after cell permeabilization. Investigations of the mechanism of action of the complexes indicate that C2 promotes cell cycle arrest in the Sub-G 1 phase in MDA-MB-231, inhibits its colony formation, and has a possible antimetastatic action, impeding cell migration in the wound-healing experiment (13% of wound healing in 24 h). The in vivo toxicological experiments with zebrafish indicate that C1 and C3 exhibit the most zebrafish embryo developmental toxicity (inhibition of spontaneous movements and heartbeats), while C2 , the most promising anticancer drug in the in vitro preclinical tests, revealed the lowest toxicity in in vivo preclinical screening.

In this work we present the synthesis and characterization of six new ruthenium compounds with general formulae [Ru(L)(dppb)(bipy)]PF 6 and [Ru(L)(dppe) 2 ]PF 6 where L = salicylic acid (Sal), 4-aminosalicylic acid (AmSal) or 2,4-dihydroxybenzoic acid (DiSal), dppb = 1,4-bis(diphenylphosphino)butane, dppe = 1,2-bis(diphenylphosphino)ethane and bipy = 2,2'-bipyridine. The complexes were characterized by elemental analysis, molar conductivity, cyclic voltammetry, NMR, UV-vis and IR spectroscopies, and two by X-ray crystallography. The 31 P{ 1 H} NMR spectra of the complexes with the general formula [Ru(L)(dppe) 2 ]PF 6 showed that the phosphorus signals are solvent-dependent. Aprotic solvents, which form strong hydrogen bonds with the complexes, inhibit the free rotation of the salicylic acid-based, modifying the diphosphine cone angles, leading to distortion of the phosphorus signals in the NMR spectra. The cytotoxicity of the complexes was evaluated in MCF-7, MDA-MB-231, SKBR3 human breast tumor cells, and MCF-10 non-tumor cell lines. The complexes with the structural formula [Ru(L)(dppe) 2 ]PF 6 were the most cytotoxic, and the complex [Ru(AmSal)(dppe) 2 ]PF 6 with L = 4-aminosalicylic acid ligand was the most selective for the MDA-MB-231 cell line. This complex interacts with the transferrin and induces apoptosis through the intrinsic pathway, as demonstrated by increased levels of proteins involved in apoptotic cell death., 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 © 2022 Elsevier Masson SAS. All rights reserved.)

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.

In this paper, four new ruthenium complexes, [Ru(N-S)(dppm)2]PF6 (1), [Ru(N-S)(dppe)2]PF6 (2), [Ru(N-S)2(dppp)] (3) and [Ru(N-S)2(PPh3)2] (4) [dppm = 1,1-bis(diphenylphosphino)methane, dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane, PPh3 = triphenylphosphine and N-S = 2-mercaptopyrimidine anion] were synthesized and characterized using spectroscopy techniques, molar conductance, elemental analysis, electrochemical techniques and X-ray diffraction. The DNA binding studies were investigated using voltammetry and spectroscopy techniques. The results show that all complexes exhibit a weak interaction with DNA. HSA interaction with the complexes was studied using fluorescence emission spectroscopy, where the results indicate a spontaneous interaction between the species by a static quenching mechanism. The cytotoxicity of the complexes was evaluated against A549, MDA-MB-231 and HaCat cells by MTT assay. Complexes (1) and (2), which are very active against triple negative MDA-MB-231, were subjected to further biological tests with this cell line. The cytotoxic activity triggered by the complexes was confirmed by clonogenic assay. Cell cycle analyses demonstrated marked anti-proliferative effects, especially at the G0/G1 and S phases. The morphological detection of apoptosis and necrosis - HO/PI and Annexin V-FITC/PI assay, elucidated that the type of cell death triggered by these complexes was probably by apoptosis. The in vivo toxicological assessment performed on zebrafish embryos revealed that complexes (1) and (2) did not present embryotoxic or toxic effects during embryonic and larval development showing that they are promising new prototypes of safer and more effective drugs for triple negative breast cancer treatment.

Leishmaniasis, a neglected tropical disease caused by protozoans of the genus Leishmania, kills around 20-30 thousand people in Africa, Asia, and Latin America annually and, despite its potential lethality, it can be treated and eventually cured. However, the current treatments are limited owing to severe side effects and resistance development by some Leishmania. These factors make it urgent to develop new leishmanicidal drugs. In the present study, three ruthenium(II) organometallic complexes containing as ligands the commercially available anti-inflammatories diclofenac (dic), ibuprofen (ibu), and naproxen (nap) were synthesized, characterized, and subjected to in vitro leishmanicidal activity. The in vitro cytotoxicity assays against Leishmania (L.) amazonensis and Leishmania (L.) infantum promastigotes have shown that complexes [RuCl(dic)(η 6 -p-cymene)] (1) and [RuCl(nap)(η 6 -p-cymene)] (3) were active against both Leishmania species. Complex [RuCl(ibu)(η 6 -p-cymene)] (2) has exhibited no activity. The IC 50 values for the two active complexes were respectively 7.42 and 23.55 μM, for L. (L.) amazonensis, and 8.57 and 42.25 μM, for L. (L.) infantum. Based on the toxicological results and computational analysis, we proposed a correlation between the complexes and their activity. Our results suggest both complexation to ruthenium(II) and ligands structure are key elements to leishmanicidal activity.

Thirteen new ruthenium amino acid complexes were synthesized and characterized. They were obtained by the reaction of α-amino acids (AA) with [RuCl 2 (P-P)(N-N)], where P-P=1,4-bis(diphenylphosphino)butane (dppb) or 1,3-bis(diphenylphosphino)propane (dppp) and N-N=4,4'-dimethyl-2,2'-bipyridine (4'-Mebipy), 5,5'-dimethyl-2,2'-bipyridine (5'-Mebipy) or 4,4'-Methoxy-2-2'-bipyridine (4'-MeObipy). This afforded a family of complexes formulated as [Ru(AA-H)(P-P)(N-N)]PF 6 , where AA=glycine (Gly), L-alanine (Ala), L-valine (Val), L-tyrosine (Tyr), L-tryptophan (Trp), L-histidine (His) and L-methionine (Met). All compounds were characterized by elemental analysis, spectroscopic and electrochemical techniques. The [Ru(AA-H)(P-P)(N-N)]PF 6 complexes are octahedral (the AA-H ligand binding involves N-amine and O-carboxylate), diamagnetic (low-spin d 6 , S=0) and present bands due to electronic transitions in the visible region. 1 H, 13 C{ 1 H} and 31 P{ 1 H} NMR spectra of the complexes indicate the presence of C 2 symmetry, and the identification of diastereoisomers. In vitro cytotoxicity assays of the compounds and cisplatin were carried out using MDA-MB-231 (human breast) tumor cell line and a non-tumor breast cell line (MCF-10A). Most complexes present promising results with IC 50 values comparable with the reference drug cisplatin and high selectivity indexes were found for the complexes containing L-Trp. The binding of two Ru-precursors of the type [RuCl 2 (dppb)(NN)] (N-N=4'-MeObipy or 4'-Mebipy) to the blood transporter protein human serum albumin (HSA) was evaluated by fluorescence and circular dichroism spectroscopy. Both complexes bind HSA, probably in the hydrophobic pocket near Trp214, and the Ru-complex containing 4'-MeObipy shows higher affinity for HSA than the 4'-Mebipy one., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The aim of this work was the synthesis, characterization, and cytotoxicity evaluation of three new Ru(II) complexes with a general formula [Ru(Spy)(bipy)(P-P)]PF 6 [Spy = pyridine-6-thiolate; bipy = 2,2'-bipyridine; P-P = 1,2-bis(diphenylphosphine)ethane (1); 1,3-bis(diphenylphosphine) propane (2); and 1,1'-bis(diphenylphosphino)ferrocene] (4). Complex (3) with the 1,4-bis(diphenylphosphine)butane ligand, already known from the literature, was also synthesized, to be better studied here. The cytotoxicities of the complexes toward two kinds of cancerous cells (K562 and S-180 cells) were evaluated and compared to normal cells (L-929 and PBMC) by MTT assay. The complex [Ru(Spy)(bipy)(dppb)]PF 6 (3) was selected to study both the cellular and molecular mechanisms underlying its promising anticancer action in S-180 cells. The results obtained from this study indicated that complex (3) induces cell cycle arrest in the G0/G1 phase in S-180 cells associated with a decrease in the number of cells in S phase. After 24 and 48 h of exposure to complex (3), the cell viability decreased when compared to the negative control. Complex (3) does not appear to be involved in the DNA damage, but induced changes in the mitochondrial membrane potential in S-180 cells. Furthermore, there was also an increase in the gene expression of Bax, Caspase 9, and Tp53. According to our results, complex (3) induces cell apoptosis through p53/Bax-dependent intrinsic pathway and suppresses the expression of active antiapoptotic Bcl-2 protein.

Triple-negative breast cancer (TNBC) is a highly aggressive breast cancer subtype. The high rate of metastasis associated to the fact that these cells frequently display multidrug resistance, make the treatment of metastatic disease difficult. Development of antitumor metal-based drugs was started with the discovery of cisplatin, however, the severe side effects represent a limitation for its clinical use. Ruthenium (Ru) complexes with different ligands have been successfully studied as prospective antitumor drugs. In this work, we demonstrated the activity of a series of biphosphine bipyridine Ru complexes (1) [Ru(SO4)(dppb)(bipy)], (2) [Ru(CO3)(dppb)(bipy)], (3) [Ru(C2O4)(dppb)(bipy)] and (4) [Ru(CH3CO2)(dppb)(bipy)]PF6 [where dppb = 1,4-bis(diphenylphosphino)butane and bipy = 2,2'-bipyridine], on proliferation of TNBC (MDA-MB-231), estrogen-dependent breast tumor cells (MCF-7) and a non-tumor breast cell line (MCF-10A). Complex (4) was most effective among the complexes and was selected to be further investigated on effects on tumor cell adhesion, migration, invasion and in apoptosis. Moreover, DNA and HSA binding properties of this complex were also investigated. Results show that complex (4) was more efficient inhibiting proliferation of MDA-MB-231 cells over non-tumor cells. In addition, complex (4) was able to inhibit MDA-MB231 cells adhesion, migration and invasion and to induce apoptosis and inhibit MMP-9 secretion in TNBC cells. Complex (4) should be further investigated in vivo in order to stablish its potential to improve breast cancer treatment.

The motivation to use ruthenium complexes in cancer treatment has led our research group to synthesize complexes with this metal and test them against several types of tumor cells, yielding promising results. In this paper the results of biological tests, assessed by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, were carried out on the complexes cis-[RuCl(BzCN)(bipy)(dppe)]PF6 (1), cis-[RuCl(BzCN)(bipy)(dppb)]PF6 (2), cis-[RuCl(BzCN)(bipy)(dppf)]PF6 (3) and cis-[RuCl(BzCN)(phen)(dppb)]PF6 (4) which are described [BzCN = b enzonitrile; bipy = 2,2'-bipyridine; phen = 1,10-phenanthroline; dppe = 1,2-bis(diphenylphosphino) ethane; dppb = 1,4-bis-(diphenylphosphino)butane; dppf = 1,1'-bis(diphenylphosphino)ferrocene]. The present study is focused on the cytotoxic activity of complexes (1)-(4) against four tumor cell lines and on the apoptosis and changes in the cell cycle and gene expression observed in the sarcoma 180 (S180) tumor cell line treated with complex (1). The results demonstrated that this complex inhibits S180 cell growth, with an IC50 of 17.02 ± 8.21 μM, while exhibiting lower cytotoxicity (IC50 = 53.73 ± 5.71 μM) towards lymphocytes (normal cells). Flow cytometry revealed that the complex inhibits the growth of tumor cells by inducing apoptosis as evidenced by an increase in the proportion of cells positive for annexin V staining and G0/G1 phase cell-cycle arrest. Further investigation showed that complex (1) induces a drop in the mitochondrial membrane potential and provokes a decrease in Bcl-2 protein expression and increase in caspase 3 activation, while the increased activation of caspase 8 caused a decrease in the gene expression in caspases 3 and 9. Increases in Tp53 and Bax expressions were also observed., (Copyright © 2015 Elsevier Inc. All rights reserved.)

cis-[RuCl(NO2)(dppb)(5,5'-mebipy)] (complex 1), cis-[Ru(NO2)2(dppb)(5,5'-mebipy)] (complex 2), ct-[RuCl(NO)(dppb)(5,5'-mebipy)](PF6)2 (complex 3), and cc-[RuCl(NO)(dppb)(5,5'-mebipy)](PF6)2 (complex 4), where 5,5'-mebipy is 5,5'-dimethyl-2,2'-bipyridine and dppb is 1,4-bis(diphenylphosphino)butane, were synthesized and characterized. The structure of complex 2 was determined by X-ray crystallography. These complexes exhibited a higher anti-Trypanosoma cruzi activity than benznidazole, the current antiparasitic drug. Complex 3 was the most potent, displaying a 50% effective concentration (EC50) of 2.1 ± 0.6 μM against trypomastigotes and a 50% inhibitory concentration (IC50) of 1.3 ± 0.2 μM against amastigotes, while it displayed a 50% cytotoxic concentration (CC50) of 51.4 ± 0.2 μM in macrophages. It was observed that the nitrosyl complex 3, but not its analog lacking the nitrosyl group, releases nitric oxide into parasite cells. This release has a diminished effect on the trypanosomal protease cruzain but induces substantial parasite autophagy, which is followed by a series of irreversible morphological impairments to the parasites and finally results in cell death by necrosis. In infected mice, orally administered complex 3 (five times at a dose of 75 μmol/kg of body weight) reduced blood parasitemia and increased the survival rate of the mice. Combination index analysis of complex 3 indicated that its in vitro activity against trypomastigotes is synergic with benznidazole. In addition, drug combination enhanced efficacy in infected mice, suggesting that ruthenium-nitrosyl complexes are potential constituents for drug combinations., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

The present study describes the synthesis, characterization, antileishmanial and antiplasmodial activities of novel diimine/(2,2'-bipyridine (bipy), 1,10-phenanthroline (phen), 4,4'-methylbipyridine (Me-bipy) and 4,4'-methoxybipyridine (MeO-bipy)/phosphine/ruthenium(II) complexes containing lapachol (Lap, 2-hydroxy-3-(3-33 methyl-2-buthenyl)-1,4-naphthoquinone) as bidentate ligand. The [Ru(Lap)(PPh3)2(bipy)]PF6 (1), [Ru(Lap)(PPh3)2(Me-bipy)]PF6 (2), [Ru(Lap)(PPh3)2(MeO-bipy)]PF6(3) and[Ru(Lap)(PPh3)2(phen)]PF6 (4) complexes, PPh3=triphenylphospine, were synthesized from the reactions of cis-[RuCl2(PPh3)2(X-bipy)] or cis-[RuCl2(PPh3)2(phen)], with lapachol. The [RuCl2(Lap)(dppb)] (5) [dppb=1,4-bis(diphenylphosphine)butane] was synthesized from the mer-[RuCl3(dppb)(H2O)] complex. The complexes were characterized by elemental analysis, molar conductivity, infrared and UV-vis spectroscopy, (31)P{(1)H} and (1)H NMR, and cyclic voltammetry. The Ru(III) complex, [RuCl2(Lap)(dppb)], was also characterized by the EPR technique. The structure of the complexes [Ru(Lap)(PPh3)2(bipy)]PF6 and [RuCl2(Lap)(dppb)] was elucidated by X-ray diffraction. The evaluation of the antiparasitic activities of the complexes against Leishmania amazonensis and Plasmodium falciparum demonstrated that lapachol-ruthenium complexes are more potent than the free lapachol. The [RuCl2(Lap)(dppb)] complex is the most potent and selective antiparasitic compound among the five new ruthenium complexes studied in this work, exhibiting an activity comparable to the reference drugs., (Copyright © 2014. Published by Elsevier Inc.)

This paper describes the synthesis and characterization of four new ruthenium complexes containing 1,4 bis(diphenylphosphino)butane (dppb), 2-pyridinecarboxylic acid anion (pic) and the diimines [(2,2'-bipyridine (bipy), 4,4'-dimethyl-2,2'-bipyridine (Me-bipy), 4,4'-dichloro-2,2'-bipyridine (Cl-bipy) and 1,10-phenanthroline (phen) as ligands, with formulae [Ru(pic)(dppb)(bipy)]PF(6) (SCAR01), [Ru(pic)(dppb)(Me-bipy)]PF(6) (SCAR02), [Ru(pic)(dppb)(Cl-bipy)]PF(6) (SCAR03) and [Ru(pic)(dppb)(phen)]PF(6) (SCAR04). Additionally, the in vitro anti-Mycobacterium tuberculosis (MTB) activity, cytotoxicity and activity against in vitro infection of these complexes and two more complexes, cis-[Ru(pic)(dppe)(2)]PF(6) (SCAR05) and cis-[RuCl(2)(dppb)(bipy)] (SCAR06), and their free ligands are described and discussed. All compounds showed excellent MIC against MTB, low cytotoxicity and a selectivity index higher than 10. Also, all compounds showed significant intracellular inhibition and the compound SCAR05 showed a better activity than rifampin and SQ109. This is the first report of activity against in vitro infection of ruthenium compounds., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

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 ruthenium(II) compounds cis-[Ru(bpy)2(4-bzpy)(CO)](PF6)2 (I) and cis-[Ru(bpy)2(4-bzpy)(Cl)](PF6) (II) (4-bzpy=4-benzoylpyridine, bpy=2,2'-bipyridine) were synthesized and characterized by spectroscopic and electrochemical techniques. The crystal structure of II was determined by X-ray diffraction. The photochemical behavior of I in aqueous solution shows that irradiation with ultraviolet light (365nm) releases both CO and 4-bzpy leading to the formation of the cis-[Ru(bpy)2(H2O)2]2+ ion as identified by NMR and electronic spectroscopy. Carbon monoxide release was confirmed with the myoglobin method and by gas chromatographic analysis of the headspace. CO release was not observed when aqueous I was irradiated with blue light (453nm). Changes in the electronic and 1H NMR spectra indicate that I undergoes photoaquation of 4-bzpy to form cis-[Ru(bpy)2(CO)(H2O)]2+. Blue light irradiation of aqueous II released the coordinated 4-bzpy to give the cis-[Ru(bpy)2(H2O)(Cl)]2+ ion. When the latter reaction was carried out in the presence of the nucleobase guanine, Ru-guanine adducts were formed, indicating that the metal containing photoproduct may also participate in biologically relevant reactions. The photochemical behavior of I indicates that it can release either CO or 4-bzpy depending on the wavelength chosen, a feature that may have therapeutic application.

Herein, we report on the synthesis and characterization of ruthenium compounds with the general formula [RuCl(AA-H)(NO)(dppb]PF6, where AA = glycine (1), L-alanine (2), L-phenylalanine (3) and L-valine (4), and dppb = 1,4-bis(diphenylphosphine)butane. The complexes were characterized using elemental analysis, UV/Vis and infrared spectroscopies, 1H, 13C, 31P NMR techniques, and cyclic voltammetry. Furthermore, the structures of the compounds (1) and (3) were determined using single-crystal X-ray diffraction. In vitro evaluation of the Ru(II)/nitrosyl/amino acid complexes revealed their cytotoxic activities against triple-negative MDA-MB-231 breast cancer cells, and against the non-tumor murine fibroblast cells. All the compounds decreased the percentage of viable cells, inducing cell death by apoptosis. Additionally, the Ru(II) complexes inhibited the migration of MDA-MB-231 cells at concentrations lower than 35 µM, after 48 h of exposure. Thus, these complexes may be promising agents for the treatment of triple-negative MDA-MB-231 breast cancer. [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]

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The ruthenium(II) compounds cis -[Ru(bpy) 2 (4-bzpy)(CO)](PF 6 ) 2 ( I ) and cis -[Ru(bpy) 2 (4-bzpy)(Cl)](PF 6 ) ( II ) (4-bzpy = 4-benzoylpyridine, bpy = 2,2′-bipyridine) were synthesized and characterized by spectroscopic and electrochemical techniques. The crystal structure of II was determined by X-ray diffraction. The photochemical behavior of I in aqueous solution shows that irradiation with ultraviolet light (365 nm) releases both CO and 4-bzpy leading to the formation of the cis -[Ru(bpy) 2 (H 2 O) 2 ] 2 + ion as identified by NMR and electronic spectroscopy. Carbon monoxide release was confirmed with the myoglobin method and by gas chromatographic analysis of the headspace. CO release was not observed when aqueous I was irradiated with blue light (453 nm). Changes in the electronic and 1 H NMR spectra indicate that I undergoes photoaquation of 4-bzpy to form cis -[Ru(bpy) 2 (CO)(H 2 O)] 2 + . Blue light irradiation of aqueous II released the coordinated 4-bzpy to give the cis -[Ru(bpy) 2 (H 2 O)(Cl)] 2 + ion. When the latter reaction was carried out in the presence of the nucleobase guanine, Ru-guanine adducts were formed, indicating that the metal containing photoproduct may also participate in biologically relevant reactions. The photochemical behavior of I indicates that it can release either CO or 4-bzpy depending on the wavelength chosen, a feature that may have therapeutic application. [ABSTRACT FROM AUTHOR]

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]

In this paper, the influence of pseudohalide ligands coordinated to the ruthenium center on the hydrogenation of cyclohexene was investigated. The pseudohalide complexes containing ruthenium were synthesized from the cis -[RuCl 2 (dppb)(N-N)] { where N-N = 2,2′-bipyridine (bipy) (1A) , 4,4′-dimethyl-2,2′-bipyridine (Me-bipy) (2) , or 4,4′-dimethoxy-2,2′-bipyridine (MeO-bipy) (3) , dppb = 1,4-bis(diphenylphosphino)butane}, by chloride exchange to provide complexes with general formula cis -[RuL 2 (dppb)(N-N)] {where L 2 = N 3 − (4) , (7) and (9) CN − (5) , (8) and (10) or SCN − (6) and (11) }. All complexes were characterized using spectroscopic, electrochemical techniques, as well as elemental analyses to check their molecular formulation and purity. Furthermore, crystal structure of the complexes cis -[Ru(N 3 ) 2 (dppb)(bipy)] ( 4 ), cis -[Ru(CN) 2 (dppb)(bipy)] ( 5 ), cis -[Ru(SCN) 2 (dppb)(bipy)] ( 6 ), cis -[Ru(CN) 2 (dppb)(Me-bipy)] ( 8 ), and cis -[Ru(SCN) 2 (dppb)(MeO-bipy)] ( 11 ) were determined by single-crystal X-ray diffraction, as well as the X-ray structure of the solvate complex [RuCl(CH 3 CN)(dppb)(bipy)](PF 6 ) ( 1B ). Dichloride and pseudohalide complexes containing ruthenium were applied as pre-catalysts in the hydrogenation of cyclohexene, after pre-established conditions using the cis -[RuCl 2 (dppb)(bipy)] (1A) as a target complex. The quantitative conversion of cyclohexene to cyclohexane was obtained in 5 h at 25 °C using 0.1 mol% of (1A) in methanol solution at 15 atm H 2 . The substituted bipy derivatives (2) and (3) were also effective pre-catalysts, but pseudohalides were not under these conditions. [ABSTRACT FROM AUTHOR]

This study reports on the synthesis of a new ruthenium(II) complex, cis -[Ru(PPh 3 ) 2 (lap) 2 ] ( 1 ) with two molecules of the natural product known as lapachol [lap = (2-hydroxy-3-(3-methyl-2-buthenyl)-1,4-naphthoquinone)] coordinated as bidentated by oxygen atoms and two monodentate PPh 3 (triphenylphosphine) in a cis configuration. This neutral complex was characterized by spectroscopic analysis, single-crystal X-ray diffraction, elemental analysis, molar conductivity and cyclic voltammetry. In this study, ruthenium complex trans -[Ru(lap)(PPh 3 ) 2 (phen)]PF 6 ( 2 ) was used for comparison purposes. The interaction of ruthenium complexes ( 1 ) and ( 2 ) with CT-DNA was evaluated by UV–Vis and circular dichroism and it was observed that the complexes interact weakly with the CT-DNA. The fluorescence measurements suggest that complex ( 1 ) shows stronger interaction with HSA and BSA proteins compared to complex ( 2 ). Cytotoxicity assays against A549 (lung cancer), MDA-MB-231 (breast cancer) and V79 (non-tumoral lung) revealed that complex ( 2 ) is more active (lower IC 50 values) than complex ( 1 ) and the cisplatin, used as a reference. [ABSTRACT FROM AUTHOR]

New complexes with the general formula [RuCl(NIC)(dppb)(X-bipy)]PF 6 were prepared by exchanging the Cl- trans ligand to the phosphorus atom by Nicotinamide (NIC). DNA and human serum albumin interactions were evaluated. Compound C3 showed high activity and selectiveness in WM1366 tumor lines, SK-MEL-147 and mainly CHL-1. Which were correlated to the generation of species that react to oxygen (ROS). [Display omitted] A set of new ruthenium complexes, [RuCl(NIC)(dppb)(4,4′-Me-bipy)]PF 6 (C1) , [RuCl(NIC)(dppb)(4,4′-Methoxy-bipy)]PF 6 (C2), and [RuCl(NIC)(dppb)(5,5′-Me-bipy)]PF 6 (C3), where NIC = 3-pyridinecarboxamide, 4,4′-Me-bipy = 4,4′-dimethyl-2,2′-bipyridine, 4,4′-Methoxy-bipy = 4,4′-dimethoxy-2,2′-bipyridine, and 5,5′-Me-bipy = 5,5′-dimethyl-2,2′-bipyridine were synthesized and characterized by elemental analysis, UV/Vis and infrared spectroscopy, 31P{1H},1H, 13C{1H} nuclear magnetic resonance (NMR), and cyclic voltammetry. In addition, the structure of [RuCl(NIC)(dppb)(4,4′-Me-bipy)]PF 6 was confirmed by single crystal X-ray diffraction (XRD). The solution stability study of C1-C3 showed the formation of pyridine which was coordinated due to solvent protic attacked to nicotinamide, and an elimination reaction of a carbamate group was observed. C1 - C3 interacted with DNA through intercalation, electrostatic forces of attraction, or hydrogen bonding. The complexes interacted, moderately and spontaneously, with HSA, mainly through Van der Waals and hydrogen bond interactions. An in vitro evaluation of the (C1-C3) complexes revealed a cytotoxicity against MCF-7, HepG2, A549, SK-MEL-147, WM1366, and CHL-1. A higher cytotoxicity was observed for compound (C3) against melanoma cell cancer (CHL-1). Moreover, the (C3) complex inhibited the clonogenic capacity and cell cycle progression of CHL-1 cells and induced apoptosis involving the production of reactive oxygen species (ROS). [RuCl(py)(dppb)(5,5′-Me-bipy)]PF 6 presented a very close C3 cytotoxicity against melanoma cell cancer (CHL-1). [ABSTRACT FROM AUTHOR]

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: Phosphine ruthenate complexes containing the non-innocent ligands 4-chloro-1,2-phenylenediamine (opda-Cl) and 3,3′,4,4′-tetraamminebiphenyl (diopda) were synthesized and characterized by means of X-ray diffraction, electrochemistry, 31P{1H} NMR and electronic spectroscopies. Crystals of cis-[RuCl2(dppb)(bqdi-Cl)] complex were isolated as a mixture of two conformational isomers due to different positions of the chlorine atoms of the o-phenylene ligand in relation to the P1 atom of the phosphine moiety. [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]

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]

• 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 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: 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: [RuCl3(NO)(P–P)], [P–P=R2P(CH2) n PR2 (n =1–3) and R2P(CH2)POR2, PR2–CH;PR2, R=Ph and (C6H11)2P-(CH2)2-P(C6H11)2] were obtained and characterized by 31P {1H} NMR, IR spectroscopies and cyclic voltammetry. The structures of fac-[RuCl3(NO)(P–P)], P–P=dppm (1), dppe (2), c-dppen (3) and dppp (4), mer-[RuCl3(NO)(dcpe)] (6a) and mer-[RuCl3(NO)(dppmO)] (7) have been determined by X-ray diffraction. Photochemical isomerization of fac- to mer-[RuCl3(NO)(P–P)] was observed under white light in a CH2Cl2 solution and in solid state. The isomerization processes were followed by IR and 31P {1H} spectra. The mer-[RuCl3(15NO)(dppb)] isomer was used for the definition of the phosphorus atoms in the structure of the complex in solution. The electrochemical study shows that the oxidation/reduction processes observed in these complexes are dependent on both the isomer (fac or mer) and the solvent. In CH2Cl2, the NO+ reduction potentials are less negative for the mer-isomers than for the fac ones, while in CH3CN solvent these potentials are, in general, very close for both isomers. [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 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]

Chagas'' disease, considered incurable, is a major third world parasitosis that affects millions of people in Latin America. Previous work has shown that ruthenium clotrimazole complexes are more active against Trypanosoma cruzi, causative agent of Chagas'' disease, than the corresponding free ligand. In this work, the synthesis and characterization of a series of new Ru(II) complexes with different antitrypanosomal active compounds is presented. Complexes of general formulae [RuIICl2(dmso)2L], where dmso=dimethylsulfoxide and L=5-nitro-2-furaldehyde semicarbazone (L1), N4-n-butyl-5-nitro-2-furaldehyde semicarbazone (L2) or 3-(5-nitrofuryl)acroleine semicarbazone (L3), were prepared in good yields by reaction of [RuIICl2(dmso)4] with L in ethanol or toluene solutions. Complexes were characterized by elemental analyses and electronic, FTIR, 1H and 13C NMR spectroscopies. Crystal and molecular structures of [RuCl2(dmso)2L1] and [RuCl2(dmso)2L2] were determined by X-ray diffraction methods. In both crystals the ruthenium metal atom is in a quite similar elongated octahedral environment, equatorially coordinated to the semicarbazone molecule, acting as a bidentate ligand through its azomethynic nitrogen and carbonylic oxygen atoms. The sixfold coordination is completed with the sulfur atoms of two dimethylsulfoxide ligands at cis positions and two chlorine ions at the axial positions. The proposed formula for L3 complex was supported by FTIR, NMR and theoretical studies. NOE–NMR experiments allowed to assign L3 spatial distribution in the complex. [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]