PREPARATION OF Ru/Al2O3 CATALYSTS FROM RuCl3

Increasing reduction time increases ruthenium reduction, but even after 6 h, ruthenium is not completely reduced and chlorine is not completely eliminated in Ru/Al₂O₃ prepared from RuCl₃.     

Catalytic activity of Ru/Fe2O3, obtained by adsorption of ruthenium on iron oxide supports

The effect of the method of a support preparation on its adsorption properties for ruthenium from solution and on the catalytic properties of Ru/Fe₂O₃ catalysts obtained by adsorption, has been studied. Moreover, the influence of the solvent in which a given ruthenium compound was dissolved on the properties of Ru/Fe₂O₃ catalysts was observed.     

Multi-wall carbon nanotubes supported ruthenium for glucose hydrogenation to sorbitol

Multi-wall carbon nanotubes (MWNTs) supported ruthenium prepared with an impregnation method was used as catalyst in glucose hydrogenation to sorbitol. The effects of ruthenium loading, reaction time, temperature and initial hydrogen pressure on glucose hydrogenation were investigated. Compared with Raney Ni and ruthenium supported on Al₂O₃, SiO₂, Ru/MWNTs showed higher catalytic activity.     

Ruthenium and enzyme-catalyzed dynamic kinetic resolution of alcohols

Ruthenium acts as a good catalyst for the racemization reaction of secondary alcohols and amines. Ruthenium-catalyzed racemization is coupled with enzymatic kinetic resolution to prepare chiral compounds in 100% theoretical yield. Ten ruthenium complexes (1–10) act as a good catalyst the for racemization reaction and are also compatible with DKR process. Two other ruthenium complexes [RuCl₂(PPh₃)₃] and [Cp^*RuCl(COD)] are active for racemization reaction but their successful compatibility with DKR has not yet been reported. Ru/γ-Al₂O₃ and Ru–HAP are the heterogeneous catalysts used for the racemization reaction. They have also not been employed for DKR process. Polymer supported ruthenium is employed as a reusable racemization catalyst for aerobic DKR of alcohols.     

Carbon Deposits Formed on the Surface of Ru–Ni Catalysts During the Mixed Reforming of Methane Process

Monometallic nickel and bimetallic ruthenium–nickel catalysts supported onto aluminum oxide without additives and aluminum oxide modified with MgO and CaO were prepared by an impregnation method. The catalysts were tested in the process of the mixed reforming of methane, and their properties were characterized by thermogravimetry, scanning electron microscopy, and X-ray diffractometry. The total organic carbon content of the catalysts was also measured. The promoting effect of ruthenium and structural promoters on the catalytic activity of Ni/Al₂O₃ was confirmed. The Ru–Ni/MgO–Al₂O₃ catalyst exhibited the highest stability and activity; this fact can be explained by the increased adsorption of methane on the surface of ruthenium–nickel clusters.     

Carbonyl and hydridocarbonyl complexes of ruthenium (II) and osmium (II) with tertiary arsines

Ruthenium halides (Cl and Br) react with monotertiary arsines-Ph₂RAs (R=Me, Et, Pr ⁿ ) in methoxyethanol, in the presence of aq. formaldehyde to give monocarbonyl complexes of ruthenium(II) of the type RuX₂(CO) (Ph₂RAs)₃. Carbonylation of an ethanolic solution containing ruthenium trichloride and the arsine at room temperature yieldtrans dicarbonyl compounds of the formula RuCl₂(CO)₂ (Ph₂RAs)₂. The osmium monocarbonyls OsX₂(CO) (Ph₂RAs)₃ (X=Cl, Br; R=Me, Et) react with NaBH₄ in methanol to yield complexes of the composition OsHX(CO) (Ph₂RAs)₃. The ruthenium analogues RuHCl(CO) (Ph₂RAs)₃ have also been made. Structures have been assigned to all these compounds on the basis of IR and NMR spectral results.     

Amino acid complexes of ruthenium: synthesis, characterization and cyclic voltammetric studies

Reaction of α-amino acids (HL) with [Ru(PPh₃)₃Cl₂] in the presence of a base afforded a family of complexes of type [Ru(PPh₃)₂(L)₂]. These complexes are diamagnetic (low-spin d⁶, S=0) and show ligand-field transitions in the visible region. ¹H and ³¹P NMR spectra of the complexes indicate the presence of C₂ symmetry. Cyclic voltammetry on the [Ru(PPh₃)₂(L)₂] complexes show a reversible ruthenium(II)–ruthenium(III) oxidation in the range 0.30–0.42 V vs. SCE. An irreversible ruthenium(III)–ruthenium(IV) oxidation is also displayed by two complexes near 1.5 V vs. SCE.     

Reactions of ruthenium benzylidenes with H2O to give benzaldehyde and (aqua)ruthenium complex

The second generation of Grubbs type catalyst, (PCy₃)(H₂IMes)Cl₂RuCHPh (1) undergoes the Cl replacement with CH₃CN to give cationic ruthenium carbene complexes, [(RCN)₃(H₂IMes)RuCHPh](OTf)₂ (2, R = CH₃ (a), Ph (b)) in the presence of AgOTf. The reaction of 2a with H₂O in the presence of CH₃CN gives (aqua)ruthenium complex, [Ru(H₂IMes)(NCCH₃) ₄(H₂O)](OTf)₂ (3) and benzaldehyde. Benzaldehyde is also observed in the reaction of 1 with H₂O. Plausible reaction pathways are suggested for the degradation of ruthenium benzylidenes to give benzaldehyde on the basis of the isotope labeling experiments.     

On the behaviour of Ru(I) and Ru(II) carbonyl acetates in the presence of H2 and/or acetic acid and their role in the catalytic hydrogenation of acetic acid

The reactivity of phosphine substituted ruthenium carbonyl carboxylates Ru(CO)₂(MeCOO)₂(PBu₃)₂, Ru₂(CO)₄(μ-MeCOO)₂(PBu₃)₂, Ru₄(CO)₈(μ-MeCOO)₄(PBu₃)₂ with H₂ and/or acetic acid was investigated by IR and NMR spectroscopy to clarify their role in the catalytic hydrogenation of acetic acid. Evidences were collected to suggest hydride ruthenium complexes as the catalytically active species. Equilibria among ruthenium hydrides and carboxylato complexes take place in the presence of hydrogen and acetic acid, that is in the conditions of the catalytic reaction. Nevertheless the presence of acetic acid reduces the rate of the formation of hydrides. Working at a very high temperature (180°C) polynuclear phosphido hydrides such as [Ru₆(μ-H)₆(CO)₁₀(μ-PHBu)(μ-PBu₂)₂(PBu₃)₂(μ₆-P)] were formed. These phosphido clusters are suggested as the resting state of the catalytic system.Furthermore the bi- or tetranuclear Ru(I) carboxylato complexes react with acetic acid giving a mononuclear ruthenium complex Ru(CO)₂(MeCOO)(μ-MeCOO)(PBu₃), containing a monodentate and a chelato acetato ligands. This complex was spectroscopically characterised. Its identity and structure were confirmed by its reactivity with stoichiometric amount of PPh₃ to give Ru(CO)₂(MeCOO)₂(PBu₃)(PPh₃), a new mononuclear ruthenium carbonyl carboxylate containing two different phosphines, that was fully characterised.     

氧化铝载体和氧化钡助剂对钌基氨合成催化剂结构和性能的影响

采用不同来源γ-Al2O3(市售Al2O3-1,合成Al2O3-2)作为钌基氨合成催化剂载体,利用浸渍法制备了一系列添加不同BaO助剂含量的Ba-Ru/Al2O3催化剂.通过X射线衍射(XRD)、N2-低温物理吸附、X射线荧光光谱(XRF)、透射电镜(TEM)、H2程序升温还原(H2-TPR)、NH3程序升温脱附(NH3-TPD)和X射线光电子能谱(XPS)等方法研究了不同来源的Al2O3以及BaO助剂含量对负载型钌基催化剂的物相结构、织构性质、微观形貌、表面性质和催化剂的氨合成活性等方面的影响.结果表明,载体的物理化学性质对制备的钌基氨合成催化剂的结构以及活性有较大影响.BaO助剂对催化剂的影响主要表现在两个方面:添加量不同导致BaO与γ-Al2O3的作用力不同,从而进一步影响催化体系的比表面积和孔结构性质;BaO助剂会对体系的Ru物种还原性质以及催化剂表面酸碱性质进行调节,适量BaO的加入能够极大提高反应活性,而这种最佳量与载体性质密切相关.     

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.     

The kinetics and mechanism of homogeneous hydrogen transfer from alcohols to benzylideneacetone catalyzed by dichlorotris(triphenylphosphine)ruthenium(II)

Dichlorotris(triphenylphosphine)ruthenium(II) catalyzes the hydrogen transfer from alcohols to olefins. Kinetic studies were carried out at 170–190°C using the ruthenium(II) complex as homogeneous catalyst, benzyl alcohol, diphenylcarbinol, methylphenylcarbinol and benzoin as the hydrogen donors, benzylideneacetone as the hydrogen acceptor, and dibenzyl ether as a solvent. The IR spectra and GLC were used to monitor the reaction and the isotope effects were determined in order to elucidate the role of the catalyst and the mechanism of hydrogen transfer. In the reaction mixture RuCl₂(PPh₃)₃ is converted by the alcohols into RuH₂(CO) (PPh₃)₃, which then hydrogenates benzylideneacetone. The kinetic data are compatible with the expression. reaction rate = k_obs[Ru][olefin][alcohol] The rate-determining step of this reaction is considered to be the transfer of hydrogen from the alcohol to a ruthenium species.     

Antioxidant Activity of Ruthenium Cyclopentadienyl Complexes Bearing Succinimidato and Phthalimidato Ligands

In these studies, we investigated the antioxidant activity of three ruthenium cyclopentadienyl complexes bearing different imidato ligands: (η⁵-cyclopentadienyl)Ru(CO)₂-N-methoxysuccinimidato (1), (η⁵-cyclopentadienyl)Ru(CO)₂-N-ethoxysuccinimidato (2), and (η⁵-cyclopentadienyl)Ru(CO)₂-N-phthalimidato (3). We studied the effects of ruthenium complexes 1–3 at a low concentration of 50 µM on the viability and the cell cycle of peripheral blood mononuclear cells (PBMCs) and HL-60 leukemic cells exposed to oxidative stress induced by hydrogen peroxide (H₂O₂). Moreover, we examined the influence of these complexes on DNA oxidative damage, the level of reactive oxygen species (ROS), and superoxide dismutase (SOD) activity. We have observed that ruthenium complexes 1–3 increase the viability of both normal and cancer cells decreased by H₂O₂ and also alter the HL-60 cell cycle arrested by H₂O₂ in the sub-G1 phase. In addition, we have shown that ruthenium complexes reduce the levels of ROS and oxidative DNA damage in both cell types. They also restore SOD activity reduced by H₂O₂. Our results indicate that ruthenium complexes 1–3 bearing succinimidato and phthalimidato ligands have antioxidant activity without cytotoxic effect at low concentrations. For this reason, the ruthenium complexes studied by us should be considered interesting molecules with clinical potential that require further detailed research.     

Conformational Tuning of the Intramolecular Electronic Coupling in Molecular‐Wire Biruthenium Complexes Bridged by Biphenyl Derivatives

The synthesis and characterization of a series of biphenyl‐derived binuclear ruthenium complexes with terminal {RuCl(CO)(PMe₃)₃} moieties and different structural arrangements of the phenyl rings are reported. Electrochemical studies revealed that the two metal centers of the binuclear ruthenium complexes interact with each other through the biphenyl bridge, and the redox splittings ΔE_1/2 show a strong linear correlation with cos² ?, where ? is the torsion angle between the two phenyl rings. A combination of electrochemical, UV/Vis/NIR, and in situ IR differential spectroelectrochemical analysis clearly showed that: 1) the intramolecular electronic couplings in the binuclear ruthenium complexes could be modulated by changing ?; 2) the electronic ground state of the mixed‐valent cations changes from delocalized to localized through the biphenyl bridge with increasing torsion angle ?, that is, the redox processes of these complexes change from significant involvement of the bridging ligand to an oxidation behavior with less participation of the bridge.     

Synthesis of tridentate 2,6-bis(imino)pyridyl aminechlorohydro ruthenium(II) complexes: The convenient use of amine hydrochlorides to generate metal-hydride

The reaction of low-valent ruthenium complexes with 2,6-bis(imino)pyridine ligand, [η²-N₃]Ru(η⁶-Ar) (1) or {[N₃]Ru}₂(μ-N₂) (2) with amine hydrochlorides generates six-coordinate chlorohydro ruthenium (II) complexes with amine ligands, [N₃]Ru(H)(Cl)(amine) (4). Either complex 1 or 2 activates amine hydrochlorides 3, and the amines coordinate to the ruthenium center to give complex 4. This is a convenient and useful synthetic approach to form ruthenium complexes with amine and hydride ligands using amine hydrochloride.     

Spectrophotometric Determination of Ruthenium in Solutions of Nitroso and Sulfate Complexes Using Microwave Radiation

It has been shown that ruthenium can be determined in solutions of ammonium nitrosopentachlororuthenate (NH₄)₂[Ru(NO)Cl₅] with nitroso and aquachloro complexes present simultaneously by its reaction with 1,10-phenanthroline and in solutions of sulfate complexes using microwave radiation. It is found by molecular absorption and luminescence studies that the composition of the complex formed corresponds to ruthenium(II) tris-(1,10-phenanthrolinate) {[Ru(Phen)₃]²⁺}. The complexation time is decreased by several tens of times (down to 5 min) compared to conventional heating, and a 100% yield of the complex is achieved. In the presence of HCl, the conversion of nitroso species to aquachloro ruthenium complexes upon microwave irradiation is inefficient. It is found that, compared to [Ru₂OCl₁₀]^4–, [Ru(NO)Cl₅]^2– is more labile in the complexation reactions of ruthenium with 1,10-phenanthroline under microwave irradiation. Regardless of the concentration of H₂SO₄ (1.7–12 M) in the starting solutions, ruthenium sulfate complexes can be converted in a microwave field to more labile chloride complexes.     

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.     

The state of ruthenium in nitrite-nitrate nitric acid solutions as probed by NMR

The state of ruthenium in nitric acid solutions treated with sodium nitrite has been studied by ¹⁴N, ¹⁵N, ¹⁷O, and ⁹⁹Ru NMR. In the acidity range 2.7-0.12 mol/L, the dominating ruthenium species are the [RuNO(NO₂)₂(NO₃)(H₂O)₂]⁰ and [RuNO(NO₂)₂(H₂O)₃]⁺ complexes. When the acidity is decreased to 0.06 mol/L, trinitro-and tetranitronitrosoruthenium(II) complexes predominate in solution. In an acidic medium, the trinitro-and tetranitronitrosoruthenium(II) complexes exhibit catalytic activity toward oxidation with air of nitrite to nitrate.     

The ruthenium pyrazolonate complex Ru(PMIP)2(PPh3)2: Synthesis, structure, and some properties

The new ruthenium(II) complex Ru(PMIP)₂(PPh₃)₂ (HPMIP is 4-isobutyryl-3-methyl-1-phe-nylpyrazol-5-one) was obtained from RuCl₂(PPh₃)₃ and Na(PMIP)(DME) (DME is dimethoxyethane). The structures of the complex obtained and the starting sodium pyrazolonate were determined by X-ray diffraction. The ruthenium pyrazolonate complex initiates metathetical norbornene polymerization producing high-molecular-weight polynorbornene in low yield.     

Ruthenium carbonyl derivatives of N-salicylidene-2-hydroxyaniline

The ruthenium tricarbonyl derivative [Ru(CO)₃(sha)] (1), was synthesized from reaction of [Ru₃(CO)₁₂] with N-salicylidene-2-hydroxyaniline (shaH₂) Schiff base. The corresponding reactions of the ruthenium cluster with shaH₂ in presence of a secondary ligand L,L?=?pyridine and triphenyl phosphine resulted in the formation of the dicarbonyl derivatives [Ru(CO)₂(shaH₂)(L)] (2, 3). In the presence of L?=?2-aminobenzimidazole or thiourea, two complexes [Ru(CO)₂(sha)(L)] (4, 5) were formed and the shaH₂ ligand bonded to ruthenium oxidatively. The bipyridine(bpy) derivative had the molecular formula [Ru(CO)₂(shaH)(bpy)] (6), with shaH coordinated bidentate. All complexes were characterized by elemental analysis and mass, IR, ¹H NMR and UV–Vis spectroscopy. The spectroscopic studies of these complexes revealed several structural arrangements and different tautomeric forms.