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Ruthenium Complexes (ruthenium + complex)
Kinds of Ruthenium Complexes Selected AbstractsA Trinuclear Aqua Cyano-Bridged Ruthenium Complex [{(,5 -C5H5)(PPh3)2Ru(,-CN)}2RuCl2(PPh3)(H2O)]PF6: Synthesis, Characterization and Crystal StructureEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2007Viatcheslav Vertlib Abstract The organometallic trinuclear aqua cyano-bridged complex [{(,5 -C5H5)(PPh3)2Ru(,-CN)}2RuCl2(PPh3)(H2O)]PF6 (1), in which the fragment [RuCl2(PPh3)(H2O)] acts as a bridge and an acceptor group between the two terminal cyclopentadienyl ruthenium cyano moieties, was isolated in moderate yield from the reaction of [(,5 -C5H5)(PPh3)2RuCN] with [RuCl2(PPh3)3] in THF. To the best of our knowledge, compound 1 is one of the few examples of a trinuclear array of ruthenium fragments bridged by the nitrogen atom of the,C,N, group (Ru,C,N,Ru,,N,C,Ru) with a Ru-coordinated water molecule. The new aqua complex was structurally characterized by FTIR, 1H, 13C, and 31P NMR spectroscopy, mass spectrometry, elemental analysis, single-crystal X-ray diffraction, and cyclic voltammetry. The title complex crystallizes in a triclinic unit cell a = 17.3477(6) Å, b = 17.8551(5) Å, c = 18.2460(7) Å, , = 95.693(2)°, , = 111.648(2)°, and , = 97.839(2)° in the space group P with Z = 2.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A Bimetallic Ruthenium Complex as a Catalyst Precursor for the Atom Transfer Radical Polymerization of Methacrylates at Ambient TemperatureADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4-5 2006Michel Haas Abstract The bimetallic ruthenium complex [(1,3,5- i -Pr3C6H3)Ru(,-Cl)3RuCl(C2H4)(PCy3)] has been synthesized by reaction of [(1,3,5- i -Pr3C6H3)RuCl2)]2 with one equivalent of PCy3 in the presence of ethylene. It can be used as a catalyst precursor for the controlled atom transfer radical polymerization of methacrylates at 35,°C. The resulting polymers show low polydispersities. [source] Mechanism of DNA Damage Photosensitized by Trisbipyrazyl Ruthenium Complex.PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2000Unusual Role of Cu/Zn Superoxide Dismutase ABSTRACT Trisbipyrazyl ruthenium(II) (Ru[bpz]32+) was examined as DNA photosensitizer. Damage resulting from the photolysis of synthetic oligonucleotides has been monitored by polyacrylamide gel electrophoresis. Photoadduct formation is found on both single- and double-stranded oligonucleotides. On oligonucleotide duplex, oxidative damage occurs selectively at the 5,G of the 5,GG3, site and to a lesser extent at the 5,G of a GA sequence. These findings suggest the involvement of electron transfer and show that this mechanism is the main DNA damaging process involved in Ru(bpz)32+ photosensitization. In addition, photoadducts and oxidative damage are both highly affected by an increase of salt concentration in the reaction medium, stressing the importance of direct interactions between nucleic acid bases and the excited ruthenium complex for efficient electron transfer. On single-stranded oligonucleotides, all the guanines are oxidized to the same extent. In this case, oxidative damage, which is not affected by an increase of salt in the solution, has been attributed, in part, to singlet oxygen. More importantly, Cu/Zn superoxide dismutase (SOD) strongly enhances the yield of all damage, correlated to an increase of both electron transfer and singlet oxygen production. This original activity of SOD is the first example of bioactivation of a polyazaaromatic ruthenium complex. [source] Decomposition of Formic Acid Catalyzed by a Phosphine-Free Ruthenium Complex in a Task-Specific Ionic LiquidCHEMCATCHEM, Issue 10 2010Jackson D. Scholten Abstract The dehydrogenation of formic acid is effectively catalyzed by the Ru complex [{RuCl2(p -cymene)}2] dissolved in the ionic liquid (IL) 1-(2-(diethylamino)ethyl)-3-methylimidazolium chloride at 80,°C without additional bases. This catalytic system gives TOF values of up to 1540,h,1. Preliminary kinetic insights show formal reaction orders of 0.70(±0.15), 0.78(±0.03) and 2.00(±0.17) for the Ru catalyst, IL,1, and formic acid, respectively. The apparent activation energy of this process is estimated to be (69.1±7.6),kJ,mol,1. In addition, dimeric Ru hydride ionic species involved in the reaction, such as [{Ru(p -cymene)}2{(H),-(H)-,-(HCO2)}]+ and [{Ru(p -cymene)}2{(H),-(Cl),-(HCO2)}]+, are identified by mass spectrometry. The presence of water in large amounts inhibits higher conversions. Finally, a remarkable catalytic activity is observed during recycles, indicating this system's potential for hydrogen gas production. [source] ChemInform Abstract: Highly Efficient Oxidation of Alcohols Using Oxone® as Oxidant Catalyzed by Ruthenium Complex under Mild Reaction Conditions.CHEMINFORM, Issue 49 2008Zi Qiang Lei Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Oxidation of Anisoles to p-Benzoquinone Monoketals Catalyzed by a Ruthenium Complex of 1,4,7-Trimethyl-1,4,7-triazacyclononane with tert-Butyl Hydroperoxide.CHEMINFORM, Issue 10 2006Wai-Hung Cheung Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] A Silica Gel Supported Ruthenium Complex of 1,4,7-Trimethyl-1,4,7-triazacyclononane as Recyclable Catalyst for Chemoselective Oxidation of Alcohols and Alkenes by tert-Butyl Hydroperoxide.CHEMINFORM, Issue 14 2003Wai-Hung Cheung Abstract For Abstract see ChemInform Abstract in Full Text. [source] Influence of pH on the Photochemical and Electrochemical Reduction of the Dinuclear Ruthenium Complex, [(phen)2Ru(tatpp)Ru(phen)2]Cl4, in Water: Proton-Coupled Sequential and Concerted Multi-Electron ReductionCHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2005Norma R. de Tacconi Prof. Abstract The dinuclear ruthenium complex [(phen)2Ru(tatpp)Ru(phen)2]4+ (P; in which phen is 1,10-phenanthroline and tatpp is 9,11,20,22-tetraaza tetrapyrido[3,2-a:2,3,-c:3,,,2,,-l:2,,,,3,,,]-pentacene) undergoes a photodriven two-electron reduction in aqueous solution, thus storing light energy as chemical potential within its structure. The mechanism of this reduction is strongly influenced by the pH, in that basic conditions favor a sequential process involving two one-electron reductions and neutral or slightly acidic conditions favor a proton-coupled, bielectronic process. In this complex, the central tatpp ligand is the site of electron storage and protonation of the central aza nitrogen atoms in the reduced products is observed as a function of the solution pH. The reduction mechanism and characterization of the rich array of products were determined by using a combination of cyclic and AC voltammetry along with UV-visible reflectance spectroelectrochemistry experiments. Both the reduction and protonation state of P could be followed as a function of pH and potential. From these data, estimates of the various reduced species' pKa values were obtained and the mechanism to form the doubly reduced, doubly protonated complex, [(phen)2Ru(H2tatpp)Ru(phen)2]4+ (H2P) at low pH (,7) could be shown to be a two-proton, two-electron process. Importantly, H2P is also formed in the photochemical reaction with sacrificial reducing agents, albeit at reduced yields relative to those at higher pH. [source] MCM-41 Bound Ruthenium Complex as Heterogeneous Catalyst for Hydrogenation I: Effect of Support, Ligand and Solvent on the Catalyst PerformanceCHINESE JOURNAL OF CHEMISTRY, Issue 7 2006Ying-Min Yu Abstract The functionalized MCM-41 mesoporous bound ruthenium complex was synthesized and characterized using elemental analysis, atomic absorption spectrophotometer, BET, XRD and FTIR. Hydrogenation of carbon dioxide to formic acid was investigated over these catalysts under supercritical CO2 condition. The effect of reactant gas partial pressure, supports, solvents and ligands on the synthesis of formic acid was studied. These factors could influence the catalyst activity, stability and reuse performance greatly and no byproduct was detected. These promising catalysts also offered the industrial advantages such as easy separation. [source] Variable Coordination Modes of Benzaldehyde Thiosemicarbazones , Synthesis, Structure, and Electrochemical Properties of Some Ruthenium ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29 2008Swati Dutta Abstract Reaction of benzaldehyde thiosemicarbazones [H2LR, where H2 stands for the two protons, the hydrazinic proton, and the phenyl proton at the ortho position, with respect to the imine function and R (R = OCH3, CH3, H, Cl, and NO2) for the para substituent] with [Ru(PPh3)2(CO)2Cl2], carried out in refluxing ethanol, afforded monomeric complexes of type [Ru(PPh3)2(CO)(HLR)(H)]. The crystal structure of the [Ru(PPh3)2(CO)(HLNO2)(H)] complex was determined. The thiosemicarbazone ligand is coordinated to the ruthenium center as a bidentate N,S-donor ligand forming a four-membered chelate ring. When the reaction of the thiosemicarbazones with [Ru(PPh3)2(CO)2Cl2] was carried out in refluxing toluene, a family of dimeric complexes of type [Ru2(PPh3)2(CO)2(LR)2] were obtained. The crystal structure of [Ru2(PPh3)2(CO)2(LCl)2] was determined. Each thiosemicarbazone ligand is coordinated to one ruthenium atom, by dissociation of the two protons, as a dianionic tridentate C,N,S-donor ligand, and at the same time the sulfur atom is also bonded to the second ruthenium center. 1H NMR spectra of the complexes of both types are in excellent agreement with their compositions. All the dimeric and monomeric complexes are diamagnetic (low-spin d6, S = 0) and show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry of the [Ru(PPh3)2(CO)(HLR)(H)] and [Ru2(PPh3)2(CO)2(LR)2] complexes show the ruthenium(II),ruthenium(III) oxidation within 0.48,0.73 V vs. SCE followed by a ruthenium(III),ruthenium(IV) oxidation within 1.09,1.47 V vs. SCE. Potentials of both the oxidations are found to correlate linearly with the electron-withdrawing character of the substituent R. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Efficient Functionalisation of Cubic Monovinylsilsesquioxanes via Cross-Metathesis and Silylative Coupling with Olefins in the Presence of Ruthenium ComplexesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2009Patrycja Abstract Monovinylheptaisobutylsilsesquioxane undergoes efficient cross-metathesis and silylative coupling with styrenes. Allyl derivatives were successfully tested in cross-metathesis in the presence of first generation Grubbs' catalyst, while heteroatom-substituted vinyl derivatives (vinyl ethers, 9-vinylcarbazole) efficiently undergo silylative coupling catalysed by ruthenium hydride complexes. Both reactions proceed highly stereoselectively and lead to nearly quantitative formation of E isomers. Only when vinyl ethers are used does the reaction lead to a mixture of stereoisomers. Atmospheric pressure photoionisation has been successfully used for recording mass spectra of the functionalised silsesquioxanes. [source] Homogeneous Photocatalytic Oxidation of Alcohols by a Chromophore,Catalyst Dyad of Ruthenium Complexes,ANGEWANDTE CHEMIE, Issue 51 2009Weizhong Chen Dr. Eine Chromophor-Katalysator-Dyade aus Rutheniumpolypyridylkomplexen wurde synthetisiert und sowohl strukturell als auch elektronisch charakterisiert. Ihre Eignung für die protonengekoppelte Mehrelektronenphotooxidation wurde anhand der photokatalytischen Oxidation aliphatischer und benzylischer Alkohole unter Bestrahlung mit sichtbarem Licht gezeigt, die in Wasser unter Umgebungsbedingungen hohe Selektivitäten und Umsatzzyklen über 100 liefert. [source] Asymmetric Dehydrative Cyclization of ,-Hydroxy Allyl Alcohols Catalyzed by Ruthenium Complexes,ANGEWANDTE CHEMIE, Issue 47 2009Shinji Tanaka Dr. Neue axial-chirale Liganden und ihre Allylester wurden hergestellt. Die Kombination dieser Liganden mit [CpRu(CH3CN)3]PF6 ermöglicht eine hoch effiziente intramolekulare dehydratisierende Cyclisierung von ,-Hydroxyallylalkoholen zu ,-Alkenyl-substituierten cyclischen Ethern ohne Aktivierung der Allyleinheiten (siehe Schema; Cp=Cyclopentadienyl, Naph=Naphthyl, Py=Pyridin). In manchen Fällen wurden Enantiomerenverhältnisse über 99:1 erzielt. [source] ChemInform Abstract: Asymmetric Dehydrative Cyclization of ,-Hydroxy Allyl Alcohols Catalyzed by Ruthenium Complexes.CHEMINFORM, Issue 10 2010Shinji Tanaka Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Nitrogen-Directed ortho-Selective Homocoupling of Aromatic Compounds Catalyzed by Ruthenium Complexes.CHEMINFORM, Issue 36 2008Shuichi Oi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Catalytic Applications of 1,2,4-Diazaphospholide-Based Ruthenium Complexes in the Heck Reaction.CHEMINFORM, Issue 14 2008Jake Yorke Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: The Oxime Bond Formation as an Efficient Tool for the Conjugation of Ruthenium Complexes to Oligonucleotides and Peptides.CHEMINFORM, Issue 7 2008Mathilde Villien Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Activated Pyridinium-Tagged Ruthenium Complexes as Efficient Catalysts for Ring-Closing Metathesis.CHEMINFORM, Issue 19 2007Diane Rix Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Ruthenium Complexes of Phosphine,Aminophosphine Ligands.CHEMINFORM, Issue 39 2006Neil W. Boaz Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Olefin Metathesis in Room Temperature Ionic Liquids Using Imidazolium-Tagged Ruthenium Complexes.CHEMINFORM, Issue 46 2005Herve Clavier Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Highly Selective Synthesis of (E)-N-Aryl-N-(1-propenyl) Ethanamides via Isomerization of N-Allyl Ethanamides Catalyzed by Ruthenium Complexes.CHEMINFORM, Issue 52 2001Stanislaw Krompiec Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: First Ruthenium Complexes with a Chelating Arene Carbene Ligand as Catalytic Precursors for Alkene Metathesis and Cycloisomerization.CHEMINFORM, Issue 32 2001Bekir Cetinkaya Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Hydrolysis of Dinuclear Ruthenium Complexes [{CpRu(PPh3)2}2(,,,1:1 -L)][CF3SO3]2 (L=P4, P4S3): Simple Access to Metal Complexes of P2H4 and PH2SHCHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2007Pierluigi Barbaro Dr. Abstract The reaction of [CpRu(PPh3)2Cl] (1) with half an equivalent of P4 or P4S3 in the presence of AgCF3SO3 as chloride scavenger affords the stable dimetal complexes [{CpRu(PPh3)2}2(,,,1:1 -P4)][CF3SO3]2, 3,CH2Cl2 (2) and [{CpRu(PPh3)2}2(,,,1:1 -Papical -Pbasal -P4S3)][CF3SO3]2, 0.5,C7H8 (3), in which the tetrahedral P4 and mixed-cage P4S3 molecules are respectively bound to two CpRu(PPh3)2 fragments through two phosphorus atoms. The coordinated cage molecules, at variance with the free ligands, readily react with an excess of water in THF under mild conditions. Among the hydrolysis products, the new, remarkably stable complexes [{CpRu(PPh3)2}2(,,,1:1 -P2H4)][CF3SO3]2 (4) and [CpRu(PPh3)2(,1 -PH2SH)]CF3SO3 (8) were isolated. In the former, diphosphane, P2H4, is coordinated to two CpRu(PPh3)2 fragments, and in the latter thiophosphinous acid, H2PSH, is coordinated to the metal centre through the phosphorus atom. All compounds were characterised by elemental analyses and IR and NMR spectroscopy. The crystal structures of 2, 3, 4 and 8 were determined by X-ray diffraction. [source] Systematic Evaluation of Substituted Cyclopentadienyl Ruthenium Complexes, [(,5 -C5MenH5,n)RuCl(cod)], for Catalytic Cycloadditions of DiynesCHEMISTRY - AN ASIAN JOURNAL, Issue 4 2010Yoshihiko Yamamoto Prof. Abstract A series of ,5 -cyclopentadienylruthenium complexes, [(,5 -C5MenH5,n)RuCl(cod)] (cod=1,5-cyclooctadiene), are evaluated as catalysts for the cycloaddition of 1,6-diynes with alkynes. As a result, we unexpectedly found that the complex bearing the 1,2,4-Me3Cp ligand is the most efficient catalyst in terms of turnover number (TON) for the cycloaddition of a bulky diiododiyne with acetylene, recording the highest TON of 970 with a catalyst loading of 0.1,mol,%. To obtain insight into this result, we evaluate the electron richness of all complexes by cyclic voltammetric analyses, which indicate that the electron density of the ruthenium center increases with an increase in methyl substitution on the Cp, ligands. The initial rate (up to 10,% conversion) of the cycloaddition was then measured using 1H,NMR spectroscopy. The initial rate is found to decrease as the number of methyl substituents increases. According to these results, we assumed that the optimum catalytic performance exhibited by the 1,2,4-trimethylcyclopentadienyl complex can be attributed to its robustness under the catalytic cycloaddition conditions. The steric and electronic effects of the Cp, ligands are also investigated in terms of the regioselectivity of the cycloaddition of an unsymmetrical diyne and in terms of the chemoselectivity in the cycloaddition of a 1,6-heptadiyne with norbornene. [source] Chiral Half-Sandwich Ruthenium(II) Complexes as Catalysts in 1,3-Dipolar Cycloaddition Reactions of Nitrones with Methacrolein,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2006Daniel Carmona Abstract Ruthenium complexes of formula [(,6 -arene)Ru(LL*)(H2O)][SbF6]2 (arene = C6H6, p -MeC6H4iPr, C6Me6; LL* = bidentate chelate chiral ligand with PN, PP or NN donor atoms) have been tested as catalyst precursors for the asymmetric 1,3-dipolar cycloaddition of nitrones to methacrolein. The reaction occurs quantitatively with perfect endo selectivity and moderate enantioselectivity (up to 74,% ee). The ruthenium aqua complexes can be prepared from the corresponding chlorides, [(,6 -arene)RuCl(LL*)][SbF6]. Dipolarophile intermediates [(,6 -arene)Ru(PNiPr)(methacrolein)][SbF6]2 {PNiPr = (4S)-2-(2-diphenylphosphanylphenyl)-4-isopropyl-1,3-oxazoline} as well as nitrone-containing complexes [(p -MeC6H4iPr)Ru(PNiPr)(nitrone)][SbF6]2 (nitrone = N -benzylidenephenylamine N -oxide, N -benzylidenemethylamine N -oxide, 3,4-dihydroisoquinoline N -oxide) have been also isolated and characterised. The crystal structures of the chlorides (RRu)-[(,6 -C6Me6)RuCl(PNiPr)][SbF6], (RRu)-[(,6 -C6H6)RuCl(PNInd)][SbF6] {PNInd = (3aR,8aS)-2-[2-(diphenylphosphanyl)phenyl]-3a,8a-dihydroindane[1,2- d]oxazole} and those of the aqua solvates (RRu)-[(,6 -arene)Ru(PNiPr)(H2O)][SbF6]2 (arene = C6H6, C6Me6) were determined by X-ray diffraction methods. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Ruthenium-Catalyzed Allenyl Carbamate Formation from Propargyl Alcohols and IsocyanatesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2008Edgar Haak Abstract Ruthenium complexes of redox-coupled cyclopentadienone ligands catalyze the formation of allenyl carbamates from propargyl alcohols and isocyanates. This efficient and atom-economical process represents the first catalytic access to allenyl carbamates, compounds of high synthetic potential. The reaction needs an acidic co-catalyst and can be performed at room temperature. In addition, new (cyclopentadienone)iron and -ruthenium complexes were synthesized, and mechanistic aspects regarding catalytic transformations of propargyl systems with ruthenium catalysts are obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Ruthenium-Catalyzed Asymmetric Epoxidation of Olefins Using H2O2, Part II: Catalytic Activities and MechanismCHEMISTRY - A EUROPEAN JOURNAL, Issue 7 2006Man Kin Tse Dr. Abstract Asymmetric epoxidation of olefins with 30,% H2O2 in the presence of [Ru(pybox)(pydic)] 1 and [Ru(pyboxazine)(pydic)] 2 has been studied in detail (pybox=pyridine-2,6-bisoxazoline, pyboxazine=pyridine-2,6-bisoxazine, pydic=2,6-pyridinedicarboxylate). 35 Ruthenium complexes with sterically and electronically different substituents have been tested in environmentally benign epoxidation reactions. Mono-, 1,1-di-, cis - and trans -1,2-di-, tri-, and tetra-substituted aromatic olefins with versatile functional groups can be epoxidized with this type of catalyst in good to excellent yields (up to 100,%) with moderate to good enantioselectivies (up to 84,% ee). Additive and solvent effects as well as the relative rate of reaction with different catalysts have been established. It is shown that the presence of weak organic acids or an electron-withdrawing group on the catalyst increases the reactivity. New insights on the reaction intermediates and reaction pathway of the ruthenium-catalyzed epoxidation are proposed on the basis of density functional theory calculation and experiments. [source] Chiral Ruthenium,Allenylidene Complexes That Bear a Fullerene Cyclopentadienyl Ligand: Synthesis, Characterization, and Remote Chirality TransferCHEMISTRY - AN ASIAN JOURNAL, Issue 3 2007Yu-Wu Zhong Dr. Abstract Ruthenium complexes that bear both a fullerene and an allenylidene ligand, [Ru(C60Me5)((R)-prophos)=CCCR1R2]PF6 (prophos=1,2-bis(diphenylphosphanyl)propane), were prepared by the reaction of [Ru(C60Me5)Cl((R)-prophos)] and a propargyl alcohol in better than 90,% yields, and characterized by 1H, 13C, and 31P,NMR, IR, and UV/Vis/NIR spectroscopy and MS. Cyclic voltammograms of these complexes showed one reversible or irreversible reduction wave due to the allenylidene part, and two reversible reduction waves due to the fullerene core. Nucleophilic addition of RMgBr or RLi proceeded regioselectively at the distal carbon atom of the allenylidene array. The reaction took place with a 60:40,95:5 level of diastereoselectivity with respect to the original chirality in the (R)-prophos ligand, which is located six atoms away from the electrophilic carbon center. [source] 16-Electron (Arene)ruthenium Complexes with Superbasic Bis(imidazolin-2-imine) Ligands and Their Use in Catalytic Transfer HydrogenationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29-30 2009Thomas Glöge Abstract The ligands N,N, -bis(1,3,4,5-tetramethylimidazolin-2-ylidene)-1,2-ethanediamine (BLMe) and N,N, -bis(1,3-diisopropyl-4,5-dimethylimidazolin-2-ylidene)-1,2-ethanediamine(BLiPr) react with [(,5 -C5Me5)RuCl]4 to afford cationic 16-electron half-sandwich complexes [(,5 -C5Me5)Ru(BLR)]+ (R = Me, 3; R = iPr, 4), which resist coordination of the chloride counterion because of the strong electron-donating ability of the diimine ligands. Upon reaction with [(,6 -C6H6)RuCl2]2 or [(,6 -C10H14)RuCl2]2, these ligands stabilize dicationic 16-electron benzene and cymene complexes of the type [(,6 -C6H6)Ru(BLR)]2+ (R = Me, 5; R = iPr, 6) and [(,6 -C10H14)Ru(BLR)]2+ (R = Me, 7; R = iPr, 8). The X-ray crystal structure of [5]Cl2 reveals the absence of any direct Ru,Cl interaction, whereas a long Ru,Cl bond, supported by two CH···Cl hydrogen bonds, is observed for [(6)Cl]Cl in the solid state. Treatment of the dichlorides of 6 and 8 with NaBF4 affords [6](BF4)2 and [8](BF4)2, which are composed of individual dications and tetrafluoroborate ions with no direct Ru,F interaction. All complexes catalyze the transfer hydrogenation of acetophenone in boiling 2-propanol. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] A spectroscopic study of the reaction of NAMI, a novel ruthenium(III)anti-neoplastic complex, with bovine serum albuminFEBS JOURNAL, Issue 4 2000Luigi Messori The reaction of Na[transRuCl4Me2SO(Im)] (NAMI; where Im is imidazole), a novel anti-neoplastic ruthenium(III) complex, with BSA, was studied in detail by various physico-chemical techniques. It is shown that NAMI, following chloride hydrolysis, binds bovine serum albumin tightly; spectrophotometric and atomic absorption data point out that up to five ruthenium ions are bound per albumin molecule when BSA is incubated for 24 h with an eightfold excess of NAMI. CD and electronic absorption results show that the various ruthenium centers bound to albumin exhibit well distinct spectroscopic features. The first ruthenium equivalent produces a characteristic positive CD band at 415 nm whereas the following NAMI equivalents produce less specific and less marked spectral effects. At high NAMI/BSA molar ratios a broad negative CD band develops at 590 nm. Evidence is provided that the bound ruthenium centers remain in the oxidation state +3. By analogy with the case of transferrins it is proposed that the BSA-bound ruthenium ions are ligated to surface histidines of the protein; results from chemical modification experiments with diethylpyrocarbonate seem to favor this view. Spectral patterns similar to those shown by NAMI are observed when BSA is reacted with two strictly related ruthenium(III) complexes Na[transRuCl4(Me2SO)2] and H(Im)[transRuCl4(Im)2] (ICR), implying a similar mechanism of interaction in all cases. It is suggested that the described NAMI-BSA adducts may form in vivo and may be relevant for the biological properties of this complex; alternatively NAMI/BSA adducts may be tested as specific carriers of the ruthenium complex to cancer cells. Implications of these findings for the mechanism of action of NAMI and of related ruthenium(III) complexes are discussed. [source] | |||||||||||||||||||||||||||||||