Presence Of RuCl2 Research Articles

High activity and excellent durability of oxygen-vacancy-rich ruthenium manganese oxide solid-solution nanowires for the oxygen evolution reaction in acidic media

Oxygen vacancy-rich solid-solution RuxMn1−xO2 nanowires have been reported to be efficient catalysts for acidic oxygen evolution reaction. They only need an overpotential of 200 mV to drive 10 mA cm−2 and show no obvious activity drop for >600 h.

Kinetic model for cyclohexene hydromethoxycarbonylation catalyzed by RuCl3

A kinetic model for hydromethoxycarbonylation of cyclohexene in methanol in the presence of RuCl3 at 463 K was developed. The model shows a combined influence of different reactants on the reaction rate; it takes into account side reactions of cyclohexene and it satisfactorily describes the experimental data obtained at conversions of cyclohexene up to 75%.

Kinetic equations and models of cyclohexene hydrocarbomethoxylation catalyzed by the RuCl3 and RuCl3/NaCl system

Based on the kinetic data obtained earlier, the authors propose an improved mechanisms of cyclohexene hydrocarbomethoxylation and side reactions in the presence of RuCl3 and RuCl3/NaCl system. The mechanisms are complemented by ligand exchange reactions leading to deactivation of ruthenium complexes under CO effect. The paper shows that in the presence of RuCl3/NaCl catalytic system, the target product, methyl cyclohexanecarboxylate, is generated in two catalytic cycles: with the participation of neutral ruthenium complexes and anionic sodium-ruthenium complexes. In the presence of RuCl3, Ru(OCH3)Cl(CH3OH)4 is assumed to be a key intermediate, in the presence of RuCl3/NaCl system—Na[Ru(OCH3)Cl2(CH3OH)3]. For both catalysis cases, kinetic equations of fractional-rational form were obtained, which contain RuCl3 concentration and CO pressure in denominators. The obtained kinetic equations are consistent with the previously established first orders of reaction for cyclohexene and NaCl, the extreme dependences of reaction rate on CO pressure, and the nonlinear rate dependence on RuCl3 concentration with a constant value attainment. Based on the complete data sets on the effect of CO pressure as well as cyclohexene, RuCl3 and NaCl concentrations on the initial reaction rate, kinetic models of hydrocarbomethoxylation was developed.

RuO2 supported NaY zeolite catalysts: Effect of preparation methods on catalytic performance during aerobic oxidation of benzyl alcohol

The effects of preparation method for RuO2 supported zeolite catalysts on the catalytic consequences during the aerobic oxidation of benzyl alcohol to benzaldehyde were investigated. Three preparation methods, i.e., (i) simultaneous crystallization of the zeolite framework in the presence of RuCl3 (Ru(SC)/NaY), (ii) post ion-exchange with RuCl3 on the zeolite framework (Ru(IE)/NaY), and (iii) post support of preformed Ru metal nanoparticles on the zeolite surface (Ru(PS)/NaY), were used to construct three different RuO2 supported NaY zeolite catalysts. The catalyst performance was investigated as functions of the reaction time and temperature, in correlation with the structural changes of the catalysts, as analyzed by X-ray diffraction (XRD). The results revealed that the catalytic consequences were dramatically affected by the preparation methods. Although similar conversion was achieved with all three catalysts, the turnover frequency (TOF) differed. The Ru(PS)/NaY catalyst exhibited the highest TOF (33−48 h−1), whereas the other catalysts produced much lower TOFs (9−12 h−1). The Ru(PS)/NaY catalyst also had the highest activation energy (Ea) of 48.39 kJ mol−1, whereas the Ru(SC)/NaY and Ru(IE)/NaY catalysts had Ea values of 18.58 and 24.11 kJ mol−1, respectively. Notably, the Ru(PS)/NaY catalyst yielded a significantly higher pre-exponential factor of 5.22 × 105 h−1, which is about 5 orders of magnitude larger than that of the Ru(SC)/NaY catalyst (7.15 × 100 h−1). This suggests that collision between benzyl alcohol and molecular oxygen was very intensive on the Ru(PS)/NaY catalyst, which explains the higher TOF of the Ru(PS)/NaY catalyst relative to the others in spite of the higher Ea value of the former. In terms of recyclability, the pristine crystallinity of the zeolite framework was maintained in the Ru(SC)/NaY catalyst and the RuO2 phase exhibited an insignificant loss of the initial activity up to three catalytic cycles, whereas Ru(PS)/NaY showed slight loss of activity and Ru(IE)/NaY showed a significant loss of activity due to the disappearance of the RuO2 phase.

Nanostructuring of metal surfaces by corrosion for efficient water splitting

We show that simply by corroding Ni foam in an aqueous solution, it is possible to produce nanostructured surfaces. When Ni foam was corroded in water or an aqueous solution containing NaCl, a dense array of Ni(OH)2 nanosheets was produced on the surface of the foam. When corroded in the presence of RuCl3, the nanostructured surface composed of Ni(OH)2 nanosheets decorated with ultrasmall RuO2 nanoparticles was obtained. At an applied voltage of 1.7V, the combination of these two nanostructured surfaces yielded a water-splitting current density more than three times that obtained on the commercial Pt wire electrodes.

Oxidation of adamantane with 2,3,4,5,6-pentafluoroperoxybenzoic acid in the presence of RuCl3 · 3H2O

Adamantan-1-ol (1, 1-AdOH) is the most important adamantane derivative. It is used as starting compound in the synthesis of memantine and rimantadine, and 1-adamantyl ethers are efficient antioxidant additives to oils and transmission fluids, which simultaneously improve their rheological characteristics at low temperatures [1]. A known procedure for the synthesis of alcohol 1 is based on the catalytic oxidation of adamantane (2) with m-chloroperoxybenzoic acid in the presence of metal complexes. In particular, the yield of 1 in the presence of Ni, Fe, Mn, and Co complexes [2–5] ranges from 1 to 12%. Ruthenium-containing catalysts ensured preparation of adamanatan-1-ol in 66% yield [6]. However, in the latter case the reaction was accompanied by side processes leading to adamantan2-ol, adamantan-2-one, and 1-chloroadamantane. In this communication we report for the first time the oxidation of adamantane (2) with 2,3,4,5,6-pentafluoroperoxybenzoic acid (3) catalyzed by RuCl3 · 3 H2O. 2,3,4,5,6-Pentafluoroperoxybenzoic acid (3) is a stable compound whose synthesis and application were reported for the first time in [7, 8]. Peroxy acid 3 efficiently oxidizes ∆-steroids [7] and α,β-unsaturated esters [8] to the corresponding epoxy derivatives in almost quantitative yield even in the absence of a catalyst. Taking into account unusually high activity of acid 3 in reactions with olefins, we anticipated that it can be used for the selective transformation of adamantane (2) into practically important alcohol 1.

Ruthenium(II) bipyridine complexes bearing new keto–enol azoimine ligands: Synthesis, structure, electrochemistry and DFT calculations

The novel azoimine ligand, PhNHNC(COCH3)NHPh(CCH) (H2L), was synthesized and its molecular structure was determined by X-ray crystallography. Catalytic hydration of the terminal acetylene of H2L in the presence of RuCl3·3H2O in ethanol at reflux temperature yielded a ketone (L1=PhNNC(COCH3)NPh(COCH3) and an enol (L2=PhNNC(COCH3)NPhC(OH)CH2) by Markovnikov addition of water. Two mixed-ligand ruthenium complexes having general formula, trans-[Ru(bpy)(Y)Cl2] (1–2) (where Y=L1 (1) and Y=L2 (2), bpy is 2.2′-bipyrdine) were achieved by the stepwise addition of equimolar amounts of (H2L) and bpy ligands to RuCl3·3H2O in absolute ethanol. Theses complexes were characterized by elemental analyses and spectroscopic (IR, UV–Vis, and NMR (1D 1H NMR, 13C NMR, (DEPT-135), (DEPT-90), 2D 1H–1H and 13C–1H correlation (HMQC) spectroscopy)). The two complexes exhibit a quasi-reversible one electron Ru(II)/Ru(III) oxidation couple at 604mV vs. ferrocene/ferrocenium (Cp2Fe0/+) couple along with one electron ligand reduction at −1010mV. The crystal structure of complex 1 showed that the bidentate ligand L1 coordinates to Ru(II) by the azo- and imine-nitrogen donor atoms. The complex adopts a distorted trans octahedral coordination geometry of chloride ligands. The electronic spectra of 1 and 1+ in dichloromethane have been modeled by time-dependent density functional theory (TD-DFT).

Formic Acid As a Hydrogen Storage Medium: Ruthenium-Catalyzed Generation of Hydrogen from Formic Acid in Emulsions

Formic acid is decomposed to H2 and CO2 in the presence of RuCl3 and triphenylphosphines in an emulsion. In situ formed ruthenium carbonyls, such as [Ru(HCO2)2(CO)2(PPh3)2] (1), [Ru(CO)3(PPh3)2] (2), and [Ru2(HCO2)2(CO)4(PPh3)2] (3), and a large cluster, involving a Ru12 core, were identified and structurally characterized from the reaction mixtures. The catalytic activity of the mono and binuclear complexes was also investigated and it was found that [Ru2(HCO2)2(CO)4(PPh3)2] (3) shows high stability even at elevated temperatures and pressures and its activity is 1 order of magnitude lower than those measured for the mononuclear complexes. It was also attempted to use [Ru(HCO2)2(CO)2(PPh3)2] (1) as a catalyst for the hydrogenation of CO2 to formic acid under neutral conditions. Although the reduction of CO2 did not take place, the conversion of [Ru(HCO2)2(CO)2(PPh3)2] (1) to an unexpected carbonate, [Ru(CO3)(CO)2(PPh3)2]·H2O was observed.

ChemInform Abstract: Synthesis of 2‐Substituted Benzothiazoles by Visible Light‐Driven Photoredox Catalysis.

AbstractOptimal reaction conditions are found for the oxidative condensation of aminothiophenols (I) with aldehydes in the presence of RuCl2(bipy)3 as a photoredox catalyst.

Ruthenium-Catalyzed Self-Coupling of Primary and Secondary Alcohols with the Liberation of Dihydrogen

The dehydrogenative self-condensation of primary and secondary alcohols has been studied in the presence of RuCl2(IiPr)(p-cymene). The conversion of primary alcohols into esters has been further optimized by using magnesium nitride as an additive, which allows the reaction to take place at a temperature and catalyst loading lower than those described previously. Secondary alcohols were dimerized into racemic ketones by a dehydrogenative Guerbet reaction with potassium hydroxide as the additive. The transformation gave good yields of the ketone dimers with a range of alkan-2-ols, whereas more substituted secondary alcohols were unreactive. The reaction proceeds by dehydrogenation to the ketone, followed by an aldol reaction and hydrogenation of the resulting enone.

New one-pot approach to regio-synthesis of substituted 2-aminothiazoles from the corresponding keto-aziridines

Ring expansion of keto-aziridines to the corresponding 2-aminothiazoles (54–67 %) using ammonium thiocyanate in the presence of RuCl3 under refluxing acetonitrile is described. A plausible mechanism for the synthesis of substituted 2-aminothiazoles has been proposed.

Tetrazoles: LVII. Preparation and chemical properties of 1-substituted 5-arylsulfonyltetrazoles

Oxidation of 1-substituted 5-arylsulfanyltetrazoles with m-chloroperoxybenzoic acid and NaIO4 in the presence of RuCl3 leads to the formation of the 5-arylsulfonyltetrazoles. The microwave activation significantly accelerates the oxidation with sodium periodate. The phenylsulfonyl group in compounds obtained underwent the nucleophilic substitution when treated with ethanol, phenol, or benzimidazole in acetonitrile in the presence of NaOH.

ChemInform Abstract: Efficient RuIII‐Catalyzed Synthesis of 9‐Aryl‐9H‐xanthene‐3,6‐diols as Precursors to Fluorones.

Abstract Efficient condensation of resorcinol and various aromatic aldehydes in the presence of RuCl3·nH2O as a homogeneous catalyst under reflux conditions was investigated. It was found that a very simple method afforded good to excellent yields of the desired products.

The true catalyst in hydrogen transfer reactions with alcohol donors in the presence of RuCl2(PPh3)3 is ruthenium(0) nanoparticles

The widespread soluble complex RuCl2(PPh3)3 is evidently not the true catalyst in numerous hydrogen transfer reactions where it has been utilized. In the presence of alcohol donors, particularly under boiling conditions, the complex is swiftly reduced to Ru(0) and forms nanosized clusters which are the genuine catalysts. The so formed nanoparticles are not stable and they slowly agglomerate into larger non-active assemblies which are observable by the naked eye. Both the formation and the agglomeration of these nanoparticles are enhanced in the presence of a base such as NaOH. Conversely, addition of stabilizers, such as surface active agents or active carbon, inhibits the agglomeration process and elongates the life time of the catalyst although the observed activity is reduced. The presence of nanoparticles and their unique role in the catalysis of hydrogen transfer reactions between alcohols and ketones were corroborated by TEM imaging, NMR diffusion measurements, XPS and UV-vis spectroscopy and by kinetic studies.

Efficient RuIII-catalyzed synthesis of 9-aryl-9H-xanthene-3,6-diols as precursors to fluorones

Abstract Efficient condensation of resorcinol and various aromatic aldehydes in the presence of RuCl3·nH2O as a homogeneous catalyst under reflux conditions was investigated. It was found that a very simple method afforded good to excellent yields of the desired products.

ChemInform Abstract: The Asymmetric Hydrogenation of Heterocyclic Ketones

AbstractReview: 14 refs.

ChemInform Abstract: Visible‐Light Photoredox Catalysis: Dehalogenation of Vicinal Dibromo‐, α‐Halo‐, and α,α‐Dibromocarbonyl Compounds.

AbstractIn the presence of RuCl2(bipy)3, ascorbic acid, 1,5‐dimethoxynaphthalene, and visible light the title compounds undergo mild and efficient dehalogenation to afford alkenes, alkynes, monobromides, and ketones.

Preparation of tricyclic imidazopyridines by asymmetric ketone hydrogenation in the presence of RuCl 2[( S)-Xyl-P-Phos][( S)-DAIPEN

The novel complex RuCl 2[( S)-Xyl-P-Phos][( S)-DAIPEN] was identified as a highly active catalyst for the asymmetric reduction of a variety of prochiral ketones possessing an imidazo[1,2- a]pyridine scaffold. The corresponding alcohols were obtained in excellent enantiomeric purities (>96% ee) and served as valuable intermediates for the synthesis of pharmacologically active 7 H-8,9-dihydropyrano[2,3- c]imidazo[1,2- a]pyridines. The complexity of these multi-functional substrates required the development of specific reaction conditions. Whereas the reduction with RuCl 2[PP][NN] catalysts (Noyori catalysts) has never been reported to occur under aqueous conditions, in the present case, the use of aqueous isopropanol or tert-butanol was not only tolerated, but also turned out to be beneficial, especially when the reduction was conducted at high substrate to catalyst (S/C) ratios.

A Direct Synthesis of Alkenyl Alkylidene Bicyclo[3.1.0]hexane Derivatives via Ruthenium(II)-Catalysed Bicyclisation of Allenynes

The reaction of allenynes with N2CHSiMe3 in the presence of RuCl(cod)Cp* catalyst at room temperature constitutes a selective, general route to alkylidenebicyclo[3.1.0]hexanes having an adjacent Z-CH=CHSiMe3 group. The reaction shows that the RuCl(Cp*) moiety favours reductive elimination of a metallacyclobutane intermediate and not the enyne metathesis process.

Selective Ruthenium‐Catalyzed Transformations of Enynes with Diazoalkanes into Alkenylbicyclo[3.1.0]hexanes.

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