Bimetallic Ru Research Articles

2,3-Bis(2-pyridyl)thieno[3,4-b]pyrazine and its ruthenium(II) complexes: a new bidentate bridging ligand for enhanced metal-metal communication.

A new bidentate bridging ligand, bis(2-pyridyl)thieno[3,4-b]pyrazine is reported, along with its mono- and bi-metallic Ru(II) complexes as representative examples. Spectroscopic, electrochemical and X-ray crystallographic characterization of these species is reported, with the separation of the two Ru(III)/Ru(II) couples of the bimetallic complex suggesting better metal-metal communication than classical polypyridyl analogues.

Steering Photoinduced Electron Transfer in Intramolecular Photocatalysts by Peripheral Ligand Control

AbstractBridged photosensitizer‐catalyst systems are promising models to study photocatalytic hydrogen evolution. However, the systems in the literature structurally diverse and therefore hard to compare. Many systems show highly complex photophysics including several accepting orbitals for the excited state, as a result catalytic activity is hard to predict. Here we present a bimetallic Ru−Pt photocatalyst bearing peripheral spectator ligands at the ruthenium(II) photocenter as a member of the Ru‐tpphz‐Pt family. Consequently, it features a single acceptor tpphz ligand and so‐called unidirectional electron transfer, i. e., electron transfer without co‐occurring transfer to peripheral ligands, from the excited state. Thus – and in contrast to recently used peripheral ligands – the new spectator ligands do not disrupt electron transfer towards the catalytic center. By comparison to known systems, this facilitates unprecedented insight into the importance of electron transfer from the bridge to the catalytic center moving towards more rational design of oligonuclear photocatalysts.

Advancing Molecular-Scale Logic Devices through Multistage Switching in a Luminescent Bimetallic Ru(II)-Terpyridine Complex.

Stimuli-responsive multistep switching phenomena of a luminescent bimetallic Ru(II) complex are employed herein to fabricate multiple configurable logic devices. The complex exhibits "off-on" and "on-off" emission switching upon alternative treatment with visible and UV light. Additionally, remarkable augmentation of the rate as well as quantum yield of photoisomerization was achieved via the use of a chemical oxidant (Ce4+) as well as a reductant (metallic sodium). Upon exploiting the emission spectral response of the complex, several advanced Boolean logic functions, including IMPLICATION as well as 2-input 2-output and 3-input 2-output complex combinational logic gates, are successfully implemented. Additionally, by utilizing the vast efficacy of Python, a novel "logic_circuit" model is devised that is capable of making accurate decisions under the influence of various input combinations. This model transcends traditional Boolean logic gates, offering flexibility and intuition to design logical functions tailored to specific chemical contexts. By integrating principles of logic circuits with chemical processes, this innovative approach enables structure determination of the chemical states based on input conditions, thereby unlocking avenues for exploring intricate interactions and reactions beyond conventional Boolean logic paradigms.

Bimetallic Ru(II) Complex Catalysed β‐Alkylation of Secondary Alcohols and α‐Alkylation of Ketones: Selective Formation of Saturated Ketones

AbstractRu(II) bimetallic [(p‐cymene)2(RuCl)2L1]2X (X=BF4 (Cat2); X=PF6 (Cat3)) and monometallic [(p‐cymene)(RuCl)L2]BF4 (Cat4) (where L1=N,N’‐(3,3’,5,5’‐tetraisopropyl‐[1,1’‐biphenyl]‐4,4’‐diyl)bis(1‐(pyridin‐2‐yl)methanimine); L2=N‐(2,6‐diisopropyl‐phenyl)‐1‐(pyridin‐2‐yl)‐methanimine) catalyse selective synthesis of saturated ketones using β‐alkylation of secondary alcohol or α‐alkylation of ketones with primary alcohol. Notably, a single catalyst facilitates the oxidation of both secondary and primary alcohols followed by condensation and hydrogenation yielding α‐alkylated saturated ketones. Remarkably, this system allows catalyst loading as low as 0.01 mol% for β‐alkylation of secondary alcohols and 0.005 mol% for the α‐alkylation of ketone, delivering access to a wide array of α‐alkylated ketones derivatives with yields of ~97 %. Complex Cat2, in particular, orchestrates one‐pot alkylation reactions with a high turnover frequency (TOF) of 5.6 105 h−1 using as low as low catalyst loading of 0.0001 mol%. A comparative study between bimetallic and monometallic complexes reveals that complex Cat2 exhibits better selectivity for the formation of saturated ketones presumably owing to a cooperative effect between the metal centres. The scale‐up synthesis highlights the practical applicability of the catalytic approach. To delve into the plausible mechanisms, we conducted initial investigations through meticulously controlled experiments and spectroscopic analysis.

Microwave-Assisted Transfer Hydrogenation of Carbonyl and ­Nitro Compounds Using Bimetallic Ru(II) Cymene Complexes

AbstractWe report an investigation of the microwave-assisted catalytic transfer hydrogenation (TH) of carbonyl and nitro compounds by employing Ru(II) complexes: bimetallic [(p-cymene)2(RuCl)2L1]2X (X = BF4 (Cat2); X = PF6 (Cat3)) and mononuclear [(p-cymene)(RuCl)L2]BF4 (Cat4) (where L1 = N,N′-(3,3′,5,5′-tetraisopropyl-[1,1′-biphenyl]-4,4′-diyl)bis(1-(pyridin-2-yl)methanimine) and L2 = N-(2,6-diisopropylphenyl)-1-(pyridin-2-yl)methanimine). At a low catalyst loading of 0.01 mol% (Cat2/Cat3), a broad range of substrates, comprising aromatic as well as aliphatic ketones and aldehydes, undergo the TH reaction in a short reaction time of just 10 minutes. Additionally, chemoselective hydrogenation of nitroaromatic compounds is achieved under microwave irradiation in the presence of Cat2 within 5 minutes. Control experiments demonstrate that microwave heating conditions outperform conventional heating in terms of improved catalytic activity and reaction efficiency. The bimetallic catalyst Cat2 is used at a very low loading of 0.001 mol% to achieve high TONs and TOFs of 7.7 × 104 and 2.3 × 105 h–1, respectively, for the TH reaction. Spectrometry experiments involving trapping of intermediates are used to propose a mechanism for the TH of the carbonyl compounds.

A highly active and chemoselective homobimetallic ruthenium catalyst for one-pot reductive amination in water

A bimetallic Ru(ii) complex efficiently catalyzes reductive amination of diverse substrates in water with the highest reported TONs and TOFs. Experimental and DFT calculations point to a cooperative effect for the increased efficiency at low catalyst loading (0.05 mol%).

Cell Death Mechanism of Organometallic Ruthenium(II) and Iridium(III) Arene Complexes on HepG2 and Vero Cells.

Due to side effects and toxicity associated with platinum-derived metal-based drugs, extensive research has been conducted on ruthenium (Ru) complexes. We aim to synthesize a highly oil soluble Ru(II)-p-cymene complex (Ru1) with an aliphatic chain group, a bimetallic Ru(II)-p-cymene complex (Ru2) with N,S,S triple-coordination and a bimetallic Ir(III)-pentamethylcyclopentadienyl complex (Ir1) with S,S double-coordination. Subsequently, we investigate the effects of these complexes on Vero and HepG2 cell lines, focusing on cell death mechanisms. Characterization of the complexes is performed through nuclear magnetic resonance spectroscopy (1H and 13C NMR) and Fourier-transform infrared spectroscopy. The effective doses are determined using the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) (MTT) assay, applying different doses of the complexes to the two cell lines for 24 and 48 h, respectively. Immunoreactivities of Bax, Bcl2, caspase-3, RIP3, and RIPK1 are analyzed using the indirect immunoperoxidase technique. Notably, all the complexes (Ru1, Ru2, and Ir1) exhibit distinct cell death mechanisms, showing greater effectiveness than cisplatin. This study reveals the diverse mechanisms of action of Ru and Ir complexes based on different ligands. To the best of our knowledge, this study represents the first investigation of a novel RAED-type complex (Ru1) and unexpected bimetallic complexes (Ru2 and Ir1).

Catalytic partial oxidation of methane over bimetallic Ru–Ni supported on CeO2 for syngas production

Methane (CH4) is the second most abundant greenhouse gas (GHG) after carbon dioxide (CO2) and is widely recognized as one of the most destructive GHGs, exerting negative impacts on the Earth's atmosphere. In order to effectively reduce CH4 emissions, the conversion of methane into synthesis gas, which is a mixture of hydrogen (H2) and carbon monoxide (CO), has emerged as an appealing approach. Recent advancements have demonstrated that catalytic partial oxidation of methane (POM) holds great promise as a reaction pathway for syngas production. Here we study a series of catalysts consisting of monometallic Ru and Ni, and bimetallic Ru–Ni supported on CeO2. These catalysts were synthesized using both mechanochemical and conventional incipient wetness impregnation methods. Various preparation parameters were investigated, including the Ru:Ni metal ratio, the order of metal addition, and the milling energy and time for the mechanochemically prepared samples. The catalysts were subjected to low-temperature POM (350–600 °C) experiments to evaluate their performance. The experimental results reveal that the bimetallic Ru–Ni/CeO2 catalysts exhibit superior catalytic activity and stability compared to the monometallic Ru–CeO2 and Ni–CeO2 catalysts. Notably, the bimetallic Ru–Ni/CeO2 catalysts prepared through ball milling demonstrate a significantly lower temperature requirement for syngas production compared to the conventional catalysts prepared via incipient wetness impregnation.

Ru–Ni nanoparticles electrodeposited on rGO/Ni foam as a binder-free, stable and high-performance anode catalyst for direct hydrazine fuel cell

Bimetallic Ru–Ni nanoparticles was synthesized on the reduced graphene oxide decorated Ni foam (Ru–Ni/rGO/NF) by electroplating method to be utilized as the anode electrocatalyst for direct hydrazine-hydrogen peroxide fuel cells (DHzHPFCs). The synthesized electrocatalysts were characterized by X-ray diffraction, Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The electrochemical properties of catalysts towards hydrazine oxidation reaction in an alkaline medium were evaluated by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. In the case of Ru1–Ni3/rGO/NF electrocatalyst, Ru1–Ni3 provided active sites due to low activation energy (22.24 kJ mol−1) for hydrazine oxidation reaction and reduced graphene oxide facilitated charge transfer by increasing electroactive surface area (EASA = 677.5 cm2) with the small charge transfer resistance (0.1 Ω cm2). The CV curves showed that hydrazine oxidation on the synthesized electrocatalysts was a first-order reaction in low concentrations of N2H4 and the number of exchanged electrons was 3.0. In the single cell of the of direct hydrazine-hydrogen peroxide fuel cell, the maximum power density value of Ru1–Ni3/rGO/NF electrocatalyst was 206 mW cm−2 and the open circuit voltage was 1.73 V at 55 °C. These results proved that the Ru1–Ni3/rGO/NF is a promising candidate for using as the free-binder anode electrocatalyst in the future application of direct hydrazine-hydrogen peroxide fuel cells due to its excellent structural stability, ease of synthesis, low cost, and high catalytic performance.

Robust Copper-Based Nanosponge Architecture Decorated by Ruthenium with Enhanced Electrocatalytic Performance for Ambient Nitrogen Reduction to Ammonia.

Electrochemical conversion of nitrogen to green ammonia is an attractive alternative to the Haber-Bosch process. However, it is currently bottlenecked by the lack of highly efficient electrocatalysts to drive the sluggish nitrogen reduction reaction (N2RR). Herein, we strategically design a cost-effective bimetallic Ru-Cu mixture catalyst in a nanosponge (NS) architecture via a rapid and facile method. The porous NS mixture catalysts exhibit a large electrochemical active surface area and enhanced specific activity arising from the charge redistribution for improved activation and adsorption of the activated nitrogen species. Benefiting from the synergistic effect of the Cu constituent on morphology decoration and thermodynamic suppression of the competing hydrogen evolution reaction, the optimized Ru0.15Cu0.85 NS catalyst presents an impressive N2RR performance with an ammonia yield rate of 26.25 μg h-1 mgcat.-1 (corresponding to 10.5 μg h-1 cm-2) and Faradic efficiency of 4.39% as well as superior stability in alkaline medium, which was superior to that of monometallic Ru and Cu nanostructures. Additionally, this work develops a new bimetallic combination of Ru and Cu, which promotes the strategy to design efficient electrocatalysts for electrochemical ammonia production under ambient conditions.

Effect of electronic structure of energy transfer in bimetallic Ru(II)/Os(II) complexes.

Novel monometallic (μ-LL')Ru, Ru(μ-LL'), homobimetallic Ru(μ-LL')Ru, and heterodimetallic Ru(μ-LL')Os and Os(μ-LL')Ru complexes based on two asymmetrical ligands LL' (where LL' = L1L1', L2L2') have been synthesized and characterized. Spectroscopic analysis indicates that all complexes exhibit intense spin-allowed ligand-centered (LC) transitions at 288 nm and Ru-based moderate spin-allowed MLCT absorption between 440-450 nm. The Ru(μ-LL')Os and Os(μ-LL')Ru dinuclear complexes show Os-based unit absorption in the range of 565-583 nm. The Ru-based units of the complexes present different emission intensities due to differing steric hindrance at the coordination sites of the two bridging ligands. The Os(μ-LL')Ru dinuclear complexes present weaker emission intensity than their parent monometallic complexes (μ-LL')Ru. These results indicate that the emission of Os(μ-LL')Ru dinuclear complexes is quenched by the Os(II)-based units.

Designing an industrially viable bimetallic catalyst for the polyol synthesis

A bimetallic Ru–Co/Al-Basic catalyst exhibits superior sugar hydrogenation activity under modest reaction conditions as Ru and Co act synergistically.

Catalytic Synergies in Bimetallic RuPt Single–Atom Catalysts via Speciation Control (Adv. Funct. Mater. 52/2022)

Catalytic Synergies in Bimetallic RuPt Single–Atom Catalysts via Speciation Control (Adv. Funct. Mater. 52/2022)

Bimetallic Ru–Pd supported on CeO2 for the catalytic partial oxidation of methane into syngas

A series of monometallic Ru, Pd, and bimetallic Ru–Pd catalysts loaded on CeO2 support have been prepared via mechanochemical and conventional incipient wetness impregnation methods and used in the partial oxidation of methane (POM) to obtain synthesis gas (H2 and CO). The influence of the preparation method, the order of addition of the metals, the Ru:Pd metal ratio, and the milling energy and time for samples prepared by the mechanochemical method, have been evaluated between 300 and 600 °C. The results revealed that bimetallic Ru–Pd/CeO2 catalysts outperform monometallic Ru–CeO2 and Pd–CeO2 for POM, both in terms of catalytic activity and stability. Additionally, the bimetallic Ru–Pd/CeO2 catalysts prepared by ball milling produced syngas at a much lower temperature compared to the conventional catalysts prepared by incipient wetness impregnation. Raman spectroscopy, temperature programmed reduction (H2–TPR), X–ray photoelectron spectroscopy (XPS) and high–resolution transmission electron microscopy (HRTEM) have been used to characterize the catalysts before and after reaction.

Catalytic Synergies in Bimetallic RuPt Single–Atom Catalysts via Speciation Control

AbstractBimetallic single–atom catalysts (b–SACs) have recently gained prominence by virtue of the unique catalytic cooperative interactions they can exhibit, intertwining electronic and geometric effects. To date, research efforts have exclusively focused on direct mechanisms such as electron density transfer or sequential reactivity. Herein, the first study on indirect, coordination–induced catalytic synergies in carbon‐supported RuPt SACs is conducted. To this end, a holistic approach is developed, combining i) precision synthesis, ii) advanced characterization, iii) exploration of single–site adsorption properties via the hydrogen evolution reaction, and iv) modeling through density functional theory. Despite the lack of both intermetallic coordination in the first or second shell and charge redistribution effects, the RuPt SACs exhibit a H2 formation rate enhanced up to 15–fold compared with their monometallic counterparts. To unfold the origin of the intermetallic cooperativity, modifications of the structural and catalytic properties induced by the integration of a second metal species are investigated. Thus, Pt atoms are found to selectively occupy the most energeticallyfavorable cavities in the support, prompting Ru atoms to assume a distinct, more active, configuration. This contribution unveils a novel principle of bimetallic cooperativity, demonstrating the key role of integrative experimental and computational analyses in studying b–SACs.

One-pot, cascade conversion of cellulose to γ-valerolactone over a multifunctional Ru–Cu/zeolite-Y catalyst in supercritical methanol

A one-pot cascade conversion of cellulose to GVL was investigated over bimetallic Ru–Cu deposited on a zeolite Y (Ru–Cu/Z) catalyst. Under supercritical methanol conditions, high-yield (49.8%) cascade conversion of cellulose to GVL was achieved at 250 °C, with an initial H2 pressure of 3.0 MPa and reaction time of 5 h. The Ru–Cu/Z catalyst was synthesized using activated reductive deposition (ARD), which resulted in the selective deposition of Cu nanodomains on Ru nanoparticles, thereby facilitating the dissociative adsorption of H2. In addition, Lewis and Brønsted acid sites of Cu-doped zeolite Y effectively proceeded to cascade conversion reactions, including alcoholysis, isomerization, dehydration, and acetalization reactions, suppressing humin formation. The bimetallic Ru–Cu/Z catalyst was used in six consecutive runs, with a marginal loss of activity. The structure–performance relationships of the Ru–Cu/Z catalysts synthesized using ARD, incipient wet impregnation, and reduction deposition methods were compared.

Bimetallic Ru:Co Mesoporous Nanoparticles Stabilized by PEG and Imidazolium Ionic Liquid Based [KIT-6] as an Efficient Heterogeneous Catalyst for Suzuki–Miyaura Cross-Couplings in H2O:EtOH Solution

Bimetallic Ru:Co Mesoporous Nanoparticles Stabilized by PEG and Imidazolium Ionic Liquid Based [KIT-6] as an Efficient Heterogeneous Catalyst for Suzuki–Miyaura Cross-Couplings in H2O:EtOH Solution

Origin of Enhanced Ammonia Synthesis on Ru–Co Catalysts Unraveled by Density Functional Theory

Bimetallic Ru–Co catalysts have been reported as promising NH3 production catalysts that are better than various Ru–X alloys, including RuFe and pure Ru, under mild conditions; however, a systematic understanding of their superior activity is still lacking. Here, we report a comprehensive theoretical study on NH3 synthesis of Ru–Co catalysts using density functional theory and microkinetic modeling. Indeed, the RuCo surface enables more facile N2 dissociation than the Ru surface, which results from the manifested Co-induced spin symmetry breaking of Ru. We also investigated the surface phase diagram of RuCo(0001) with partial pressures of H2 and N2 gases and found that the most stable phase of the RuCo surface consists of a fraction of both N and H atoms under experimental Haber–Bosch pressure conditions; however, NH3 can be readily produced on the surfaces without severe surface poisoning issues. Furthermore, this study shows that the spin-symmetry breaking of nonmagnetic surfaces can enhance the catalytic activity for NH3 synthesis, which provides an alternative strategy to catalyst design.

Bimetallic Ru–Pd Supported on Ceo2 for the Catalytic Partial Oxidation of Methane into Syngas

Bimetallic Ru–Pd Supported on Ceo2 for the Catalytic Partial Oxidation of Methane into Syngas

Oxy-Steam Reforming of Liquefied Natural Gas (LNG) on Mono- and Bimetallic (Ag, Pt, Pd or Ru)/Ni Catalysts

This work presents, for the first time, the comparative physicochemical and reactivity studies of a range of bimetallic Pt-Ni, Pd-Ni, Ru-Ni, and Ag-Ni catalysts in the oxy-steam reforming (OSR) of liquefied natural gas (LNG) reaction towards hydrogen generation. In order to achieve the intended purpose of this work, a binary oxide CeO2·ZrO2 (1:2) support was prepared via a co-precipitation method. The catalysts’ physicochemical properties were studied using X-ray diffraction (XRD), BET, TPR-H2, TPD-NH3, SEM-EDS and XPS methods. The highest activity in the studied process was exhibited by the 1%Pt-5%Ni catalyst supported on CeO2·ZrO2 (1:2) system. The highest activity of this system is explained by the specific interactions occurring between the components of the active phase and between the components of the active phase and the carrier itself. The activity results showed that this catalytic system exhibited above 71% of the methane conversion at 600 °C and 60% yield of hydrogen formation. The results of this work demonstrate that the Pt-Ni and Ru-Ni catalytic systems hold promise to be applied in the production of hydrogen to power solid oxide fuel cells.