Properties of anodic RuNiO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>(OH)<Subscript><Emphasis Type="Italic">y</Emphasis></Subscript> catalysts synthesized on carbon supports with various dispersion degree

A number of catalysts of the (Ru-Ni)/C system is synthesized and studied for application in anodes of alkaline ethanol-air fuel cells. The carbon supports used are carbon blacks with different specific surface area and graphite powders. The X-ray photoelectron spectroscopy technique allowed detecting on the catalyst surface metallic ruthenium and nickel in the form of Ni(OH)2 hydroxide and possibly oxyhydroxide NiOOH. It is shown that the catalyst activity in the reaction of ethanol electrochemical oxidation grows at an increase in the specific surface area of the carbon support. The method of carbon monoxide oxidative desorption was used to determine the values of the specific surface area of the catalyst metallic phase. It is shown that at an increase in the relative ruthenium content from (1Ru3Ni)/C to Ru/C, the specific catalytic activity in the catalysts of the (Ru-Ni)/C system reaches the maximum value near the composition of (2Ru1Ni)/C. It is shown that the found optimum catalyst composition is independent of the carbon support dispersion degree. Activity in ethanol electrooxidation of the (2Ru1Ni)/C catalyst supported on the Ketjenblack EC-600 carbon black is 18 ± 3 A/g of the catalyst (>120 A/g of Ru) at 40°C and potential E = 0.5 V in the 2MKOH + 1 M C₂H₅OH electrolyte.     

Decomposition thermique du trichlorure de ruthenium hexammine

The thermal decomposition of [Ru(NH₃)₆]Cl₃ leads between 200 and 400° in inert gas to metallic ruthenium through the intermediates [Ru(NH₃)₅Cl]Cl₂, [Ru(NH₃)₄Cl₂]Cl and [Ru(NH₃)₃Cl₃]. In the total decomposition $$[Ru(NH_3 )_6 ]Cl_3 \to Ru + 1/2N_2 + 3NH_3 + HCl + 2NH_4 Cl$$ finely divided ruthenium is obtained above 240°. In oxygen the same intermediates are formed, the final product, however, being the metal and its dioxide.     

Formation of Ru–M/Sibunit Catalysts for Ammonia Synthesis

The effects of the nature of ruthenium and alkaline promoter precursor compounds and support properties on the activity of Ru–(Cs, K)/Sibunit catalysts in the reaction of ammonia synthesis were studied. The formation of active centers in the catalysts was studied with the use of EXAFS, XPS, and electron micro-scopy. It was found that ruthenium and a portion of cesium occurred in metallic states in the reduced catalysts. The most active catalysts containing 4 wt % ruthenium at the atomic ratios [K] : [Ru] = 4.5 and [Cs] : [Ru] = 2.5 were obtained with the use of the [Ru(dipy)₃](OH)₂ complex.     

Reactions of [Ru(CO)3Cl2]2 with aromatic nitrogen donor ligands in alcoholic media

The reactions of mono‐ and bidentate aromatic nitrogen‐containing ligands with [Ru(CO)₃Cl₂]₂ in alcohols have been studied. In alcoholic media the nitrogen ligands act as bases promoting acidic behaviour of alcohols and the formation of alkoxy carbonyls [Ru(N–N)(CO)₂Cl(COOR)] and [Ru(N)₂(CO)₂Cl(COOR)]. Other products are monomers of type [Ru(N)(CO)₃Cl₂], bridged complexes such as [Ru(CO)₃Cl₂]₂(N), and ion pairs of the type [Ru(CO)₃Cl₃]^? [Ru(N–N)(CO)₃Cl]⁺ (N–N = chelating aromatic nitrogen ligand, N = non‐chelating or bridging ligand). The reaction and the product distribution can be controlled by adjusting the reaction stoichiometry. The reactivity of the new ruthenium complexes was tested in 1‐hexene hydroformylation. The activity can be associated with the degree of stability of the complexes and the ruthenium–ligand interaction. Chelating or bridging nitrogen ligands suppresses the activity strongly compared with the bare ruthenium carbonyl chloride, while the decrease in activity is less pronounced with monodentate ligands. A plausible catalytic cycle is proposed and discussed in terms of ligand–ruthenium interactions. The reactivity of the ligands as well as the catalytic cycle was studied in detail using the computational DFT methods. Copyright © 2005 John Wiley & Sons, Ltd.     

Immobilization of ruthenium(II) salen complexes on poly(4-vinylpyridine) and their application in catalytic aldehyde olefination

Two Ru(II)(salen)(PPh₃)₂ complexes grafted on poly(4-vinylpyridine) have been synthesized and characterized. An elemental analysis shows that both grafted samples contain ca. 0.6 wt % Ru. FTIR spectra confirm the formation of metal-salen complexes attached to the carrier polymer by an interaction between the ruthenium(II) compounds with the pyridine nitrogen atoms of the poly(4-vinylpyridine). Immobilization of both Ru(II) salen complexes on the polymer increases their thermal stability as demonstrated by TG-MS analysis. The grafted materials were applied as catalysts for the olefination of various aldehydes at 60 °C under an inert gas atmosphere, showing comparable yields as their homogeneous congeners and high trans-selectivities. The ruthenium(II) compound with a larger salen ligand shows a better recyclability and selectivity than the derivative with the smaller ligand.     

Oscillations during partial oxidation of methane to synthesis gas over Ru/Al2O3 catalyst (Special column of methane transformation, Article)

Oscillations in temperatures of catalyst bed as well as concentrations of gas phase species at the exit of reactor were observed during the partial oxidation of methane to synthesis gas over Ru/Al₂O₃ in the temperature range of 600 to 850 °C. XRD, H₂-TPR and in situ Raman techniques was used to characterize the catalyst. Two types of ruthenium species, i.e. the ruthenium species weakly interacted with Al₂O₃ and that strongly interacted with the support, were identified by H₂-TPR experiment. These species are responsible for two types of oscillation profiles observed during the reaction. The oscillations were the result of these ruthenium species switching cyclically between the oxidized state and the reduced state under the reaction condition. These cyclic transformations, in turn, were the result of temperature variations caused by the varying levels of the strongly exothermic CH₄ combustion and the highly endothermic CH₄ reforming (with H₂O and CO₂) reactions (or the less exothermic direct partial oxidation of methane to CO and H₂), which were favored by the oxidized and the metallic sites, respectively. The major pathway of synthesis gas formation over the catalyst was via the combustion-reforming mechanism.     

Covalent Interaction of Ru(terpy)(tmephen)Cl+ with DNA: A Potential Ruthenium‐Based Anticancer Drug

The use of ruthenium complexes in antitumor therapy was launched two decades ago. In view of their low toxicity and good selectivity for solid tumor metastasis, ruthenium complexes have great potential as alternative drugs to cisplatin in cancer chemotherapy. A series of monochloro ruthenium complexes, Ru(terpy) (NN)Cl⁺ (NN, bidentate nitrogen ligand), containing different electron‐donating groups were prepared. The reactivity towards the formation of Ru‐DNA adduct were revealed by gel mobility shift assay. Their DNA binding sites of Ru(terpy)(tmephen)Cl⁺ were located predominantly at the purine residues i.e., guanine and adenine, by terminating DNA elongation in vitro using PCR and primer extension techniques. Surprisingly, the ability of Ru(terpy)(tmephen)Cl⁺ to inhibit cell growth was found to be approximately two times better than that of a known cross‐linking agent, Ru(bpy)₂Cl₂. Therefore, the increase in liability of the chloro ligand was demonstrated to improve the reactivity of these ruthenium complexes towards the covalent bond formation in Ru‐DNA adducts and result also in a significant inhibition of cell growth. Based on our results, these ruthenium complexes modified with electron‐rich groups provide new consideration in the tune of ruthenium‐based drugs in cancer chemotherapy.     

Electrochemistry of microparticles of tris (2,2′-bipyridine) ruthenium(II) hexafluorophosphate

The electrochemical behaviour of tris(2,2′-bipyridine)ruthenium(II) hexafluorophosphate (Ru(II)) microparticles, immobilised on a graphite electrode and adjacent to an aqueous electrolyte solution, has been studied by cyclic voltammetry and an in situ spectroelectrochemical technique. The solid Ru(II) complex exhibits one reversible redox couple with a formal potential (E_f) of 1.1 V versus Ag¦AgCl. The continuous cyclic voltammetric experiments showed that the Ru(II) microparticles are stable during the electrochemical conversions. The in situ spectroelectrochemical study showed that the absorbance at 463 nm decreased due to the oxidation of Ru(II) to Ru(III). Upon reduction, the growth of absorbance at 463 nm was observed due to the formation of Ru(II) complex and this process was reversible.     

Ruthenium(II) complexes of NSO donor ligands in the form of ring-substituted 4-phenyl-thiosemicarbazones of salicylaldehyde and o-hydroxyacetophenone

This work describes the preparation and characterisation of ruthenium(II) complexes of several ONS donor ligands in the form of ring-substituted 4-phenylthiosemicarbazones of salicylaldehyde and o-hydroxyacetophenone. Reactions of these thiosemicarbazone ligands with [Ru(PPh₃)₃]Cl₂ in refluxing MeOH furnished ruthenium(II) complexes of general formula [Ru(PPh₃)₂(LH)Cl] where the ligands acted as monoanionic tridentate ONS donors attached to the ruthenium(II) acceptor centre through the deprotonated phenolic oxygen, thione sulphur and azomethine nitrogen.     

Resolving ruthenium: XPS studies of common ruthenium materials

X‐ray photoelectron spectroscopy (XPS) utilising monochromatic Al Kα radiation has been employed to study metallic ruthenium and the catalytically and technologically important ruthenium compounds RuO₂, RuCl₃, Ru(NO)(NO₃)₃ and Ru(AcAc)₃. The results improve on the accuracy of already published Ru(3d) binding energies, expand known Ru(3p) binding energies and also report spin‐orbit splitting for the core levels. For RuO₂, the difference between anhydrous and hydrated samples is explored, and the effect on curve fitting such spectra is discussed. Analysis of RuCl₃ has allowed, for the first time, the positive identification of Ru(OH)₃ by XPS. Copyright © 2015 John Wiley & Sons, Ltd.     

Feasibility studies on the electrochemical recovery of fission platinoids from high-level liquid waste

The electrochemical behavior of ruthenium(III) and rhodium(III) in nitric acid medium has been studied at platinum and stainless steel electrodes by cyclic voltammetry. The cyclic voltammograms consisted of surge in cathodic current occurring at potentials of −0.13 V (Vs. Pd) and −0.15 V (Vs. Pd), which culminates into peaks at −0.47 V and −0.5 V due to the reductions of Ru(III) and Rh(III) to their metallic forms, respectively. Electrodeposition was carried out at stainless steel electrode and unlike palladium, the recovery of ruthenium and rhodium was limited to ~4% and ~14%, respectively. However, a different scenario was observed in case of electrodeposition from a ternary solution containing all these platinum metals. Ruthenium and rhodium deposited underpotentially in the presence of palladium and the recovery of ~20% and ~5% was observed for ruthenium and rhodium, respectively. Evolution of RuO₄ at the anode and deposition of RuO₂ in the anodic side was observed in all cases during electrolysis of ruthenium(III) containing solutions.     

Comparison of homoleptic and heteroleptic 2,2′-bipyridine and 1,10-phenanthroline ruthenium complexes as chemiluminescence and electrochemiluminescence reagents in aqueous solution

We have conducted a comprehensive comparative study of Ru(bipy)₃²⁺, Ru(bipy)₂(phen)²⁺, Ru(bipy)(phen)₂²⁺, and Ru(phen)₃²⁺ as chemiluminescence and electrochemiluminescence (ECL) reagents, to address several previous conflicting observations and gain a greater insight into their potential for chemical analysis. Clear trends were observed in many of their spectroscopic and electrochemical properties, but the relative chemiluminescence or ECL intensity with a range of analytes/co-reactants is complicated by the contribution of numerous (sometimes opposing) factors. Significantly, the reversibility of cyclic voltammetric responses for the complexes decreased as the number of phenanthroline ligands was increased, due to the lower stability of their ruthenium(III) form in the aqueous solvent. This trend was also evident over a longer timescale when the ruthenium(III) form was spectrophotometrically monitored after chemical oxidation of the ruthenium(II) complexes. In general, the greater stability of Ru(bipy)₃³⁺ resulted in lower blank signals, although this effect was less pronounced with ECL, where the reagent is oxidised in the presence of the co-reactants. Nevertheless, this shows the need to compare signal-to-blank ratios or detection limits, rather than the more common comparisons of overall signal intensity for different ruthenium complexes. Furthermore, our results support previous observations that, compared to Ru(bipy)₃²⁺, Ru(phen)₃²⁺ provides greater ECL and chemiluminescence intensities with oxalate, which in some circumstances translates to superior detection limits, but they do not support the subsequent generalised notion that Ru(phen)₃²⁺ is a more sensitive reagent than Ru(bipy)₃²⁺ for all analytes.     

Electrochemical and structural investigations of oxide films anodically formed on ruthenium-plated titanium electrodes in sulfuric acid

The electrochemical characteristics of ruthenium oxides, formed on Ru-plated Ti electrodes in 0.5 M H₂SO₄ by potential cycling with different CV upper potential limits (E _SU), were systematically compared. The repeated potential cycling between 0.2 and 0.75 V activated the formation/reduction of surface Ru oxides with hysteretic behavior. This application of repeated CVs also modified the ability of Ru deposits for hydrogen adsorption/desorption. An irreducible Ru oxide accumulated on the electrode at potentials more positive than ca. 0.95 V, whose capacitive characteristics are applicable for electrochemical supercapacitors. This irreducible oxide was composed of an aggregate consisting of Ru in various oxidation states, bridged oxygen, OH and water in a 3D-like structure with a relatively ordered and compact nature, from the X-ray photoelectron spectroscopic and voltammetric results. The surface reconstruction of the Ru deposits induced by the repeated potential cycling with E _SU≥0.75 V was clearly observed from the SEM photographs. From the X-ray diffraction patterns, all the anodically formed Ru oxides showed an amorphous nature.     

Synthesis,spectral characterization and cytotoxicity of Ru–bipyridyl complexes containing hexakis(pyrazol-1-yl)benzene (hpzb) as a co-ligand

A novel ruthenium bisbipyridine complex, [Ru(bpy)₂(hpzb)](PF₆)₂ (1) (hpzb = hexakis(pyrazol-1-yl)benzene) was obtained in the reaction between [Ru(bpy)₂Cl₂], the tritopic ligand hpzb and NH₄PF₆. A high selectivity has been found in the reaction and when the hpzb ligand was made to react with more than one ruthenium fragment, it coordinated selectively only to the first metallic fragment, and it was not possible to introduce two or three ruthenium centres. A similar complex with a deuterated bipyridine has also been obtained. The reaction with the methylated ligand hexakis(3,5-dimethylpyrazol-1-yl)benzene does not take place. A complete assignment of all the proton and carbon NMR signals of 1 was carried out. The orientation of the free pyrazolyl groups is also discussed. The redox properties and the anticancer activity of complex 1 have been studied.     

Electrochemiluminescence Based on Solid State Tri(4,7‐diphenyl‐1,10‐phenanthroline) Ruthenium(II) Ditetrakis(4‐chlorophenyl) Borate Immobilized on Carbon Fibers

A simple method for immobilization of tri(4,7‐diphenyl‐1,10‐phenanthroline) ruthenium(II) ditetrakis(4‐chlorophenyl) borate ([Ru(dpp)₃][(4‐Clph)₄B]₂) on carbon fiber electrodes was developed. Excellent electrochemical activity and electrochemiluminescence (ECL) signal of the coated carbon fiber electrodes were observed using oxalate as the co‐reactant. In addition, the effects of pH, scan rate, nitrogen and oxygen on ECL intensity were also studied. To demonstrate the reliability, the coated carbon fiber electrodes were used as ECL detectors and very low concentration of phenol was detectable (5.0×10^?8 M).     

Adducts of ruthenium(IV) thiolates with substituted pyridines. Syntheses and structures of [Ru(SMes)4(R-py)] (R = 4-Et, 4-tBu,and 3,5-Me2) and [{Ru(SMes)4}2(μ-4,4’-bipy)] (Mes = 2,4,6-trimethylphenyl)

Treatment of the trigonal-bipyramidal ruthenium(IV)–thiolate complex, [Ru(SMes)₄(MeCN)] (Mes = 2,4,6-trimethylphenyl, 1), with an anhydrous diethyl ether solution of hydrogen chloride in THF afforded [Ru(SMes)₃Cl(MeCN)] (2), whereas interaction of 1 with [Et₄N]Cl in THF gave an anionic ruthenium(IV)–thiolate complex, [Et₄N][Ru(SMes)₄Cl] (3). Reaction of 1 with one equivalent of substituted pyridines in dichloromethane gave the corresponding pyridine-coordinated ruthenium(IV)–thiolate complexes, [Ru(SMes)₄(R-py)] (R = 4-Et, 4; 4-^tBu, 5; 3,5-Me₂, 6), while reaction of 1 with 0.5 equiv. of 4,4’-bipy (4,4’-bipy = 4,4’-bipyridine) in dichloromethane resulted in the formation of a dinuclear ruthenium(IV)–thiolate complex [{Ru(SMes)₄}₂(μ-4,4’-bipy)] (7). Complexes 2–7 have been spectroscopically characterized along with their electrochemical analyses, and their structures have been determined by single-crystal X-ray diffraction.     

Synthesis and Characterization of Hyperbranched RuO2 Nanostructures

RuO₂ nanostructures were synthesized by heating Ru nanoparticles in air at 280°C using Cu as catalyst. The Ru nanoparticles were prepared by the pyrolysis of ruthenium precursors in a vacuum using multi-walled carbon nanotubes as templates. The RuO₂ nanostructures grew radically with diameters of 50–150 nm, and lengths of 0.5–2.0 μm. The growth of nanostructure mainly depends on the dispersivity of Ru nanoparticles on MWNTs. The electrochemical property of these nanostructures was studied by cyclic voltammetry. Electronic Supplementary Material Supplementary material for this article is available at and is accessible for authorized users.     

炭载钌催化剂的微波制备及其水相乙酰丙酸加氢性能

生物质衍生物乙酰丙酸是生物质转化过程中重要的平台分子,对其进行催化加氢可以得到高附加值的产物,是连接生物质转化和石油化工的重要途径。本实验研究了无溶剂微波辅助热解法绿色制备负载型钌基催化剂,以Ru₃（CO）₁₂为金属前体,碳纳米管、椰壳活性炭和活性氧化铝为催化剂载体,该制备方法简单易操作,环保高效低能耗,不使用溶剂,避免了杂质的引入和对催化剂的污染,是一种新型负载型贵金属催化剂的制备方法。同样采取传统浸渍法制备Ru/γ-Al₂O₃-IM。在乙酰丙酸水相催化加氢反应中的催化活性顺序为Ru/AC > Ru/CNT ≈ Ru/FCNT > Ru/γ-Al₂O₃-MW ≈ Ru/γ-Al₂O₃-IM。比较不同反应溶液水、甲醇、乙醇、苯甲醚、环己烷和丙酮等对于乙酰丙酸催化加氢反应的影响,并通过考察反应温度、反应压力和反应物初始浓度等因素对加氢反应的影响,确定最佳实验条件为：反应温度为90℃,反应压力2.0 MPa,适宜反应物浓度为0.10 g/mL,产品GVL收率大于99%。     

Synthesis, characterization and electron transfer properties of some picolinate complexes of ruthenium

In aqueous solution ruthenium trichloride reacted with picolinic acid (Hpic) in the presence of a base to afford [Ru(pic)₃]. In solution it shows intense ligand-to-metal charge transfer transitions near 310 and 370 nm, together with a low-intensity absorption near 2000 nm. [Ru(pic)₃] is one-electron paramagnetic and shows a rhombic ESR spectrum in 1:1 dimethylsulphoxide-methanol solution at 77 K. The distortions from octahedral symmetry have been calculated by ESR data analysis. The axial distortion is larger than the rhombic one. In acetonitrile solution it shows a reversible ruthenium(III)-ruthenium(II) reduction at −0.09 V vs. SCE and a reversible ruthenium(III)-ruthenium(IV) oxidation at 1.52 V vs. SCE. Chemical or electrochemical reduction of [Ru^III(pic)₃] gives [Ru^II(pic)₃]⁻, which in solution shows intense MLCT transitions near 360, 410 and 490 nm, and is converted back to [Ru(pic)₃] by exposure to air. Reaction of [Ru(pic)₃] with 8-quinolinol (HQ) in dimethylsulphoxide solution affords [RuQ₃]. [Ru(bpy)(pic)₂] (bpy = 2,2′-bipyridine) has been prepared by the reaction of Hpic with [Ru(bpy)(acac)₂]Cl (acac = acetylacetonate ion) in ethyleneglycol. It is diamagnetic and in solution shows intense MLCT transitions near 370, 410 and 530 nm. In acetonitrile solution it shows a reversible ruthenium(II)-ruthernium(III) oxidation at 0.44 V vs. SCE and a reversible one-electron reduction of bpy at − 1.64V vs. SCE.     

Study of the Ru/Ce system in the oxidation of carbon black and volatile organic compounds

The relationship between the state of Ru on CeO₂ and catalytic activity in the oxidation of carbon black (CB) and some volatile organic compounds (VOCs) was investigated for Ru/CeO₂ catalysts prepared by wet impregnation. It was demonstrated that the addition of ruthenium to ceria significantly improved the reactivity of the latter. The temperature programmed reduction (TPR) experiments of Ru/CeO₂ showed that the oxygen species of RuO₂ was reduced at low temperatures. In addition, Electronic Paramagnetic Resonance (EPR) studies of outgassed samples at different temperatures showed an anisotropic signal indicating that Ru(IV) was reduced to intermediate valence states like Ru(III) before its total reduction to metallic Ru. It was concluded that Ru-O-Ce bonds in the well-dispersed Ru species are highly fragile and its mobile oxygen is the active species in the catalytic oxidation process. Published in Russian in Kinetika i Kataliz, 2007, Vol. 48, No. 6, pp. 893–898. This article was submitted by the authors in English.