Organometallic Synthesis Research Articles

Precious-Group-Metal-Free Energy-Efficient Urea Electrolysis: Membrane Electrode Assembly Cell Using Ni3N Nanoparticles as Catalyst

The sluggish kinetics of the anodic oxygen evolution reaction (OER) limit the overall efficiency of green hydrogen production. The proposed strategy to overcome this is to replace OER with other kinetically favorable anodic reactions like urea oxidation reaction (UOR). Herein, we develop an organometallic synthesis of nickel nitride nanoparticles supported on carbon (Ni3N–C) as the catalyst for both UOR and hydrogen evolution reaction (HER). A precious group metal-free electrolyzer based on Ni3N–C catalyst (as both anode and cathode) is implemented for the first time, and the urea electrolyzer cell has a 200 mV lower overpotential compared to that of the water electrolyzer.

Synthesis of NiFeOx nanocatalysts from metal-organic precursors for the oxygen evolution reaction.

Production of hydrogen from a renewable source that is water requires the development of sustainable catalytic processes. This implies, among others, developing efficient catalytic materials from abundant and low-cost resources and investigating their performance, especially in the oxidation of water as this half-reaction is the bottleneck of the water splitting process. For this purpose, NiFe-based nanoparticles with sizes ca. 3-4 nm have been synthesized by an organometallic approach and characterized by complementary techniques (WAXS, TEM, STEM-HAADF, EDX, XPS, and ATR-FTIR). They display a Ni core and a mixed Ni-Fe oxide shell. Once deposited onto FTO electrodes, they have been assessed in the electrocatalytic oxygen evolution reaction under alkaline conditions. Three different Ni/Fe ratios (2/1, 1/1 and 1/9) have been studied in comparison with their monometallic counterparts. The Ni2Fe1 nanocatalyst displayed the lowest overpotential (320 mV at j = 10 mA cm-2) as well as excellent stability over 16 h.

From metal vapor to supported single atoms, clusters and nanoparticles: Recent advances to heterogeneous catalysts

The ever-increasing demand for metal catalysts on the global market has encouraged the development of new approaches for the synthesis of highly efficient catalysts. Metal and organometallic vapor-based synthesis methods allow exerting a high control over the morphological and structural features of the supported metal active phase leading to a significant contribution to design advanced catalysts and understand reaction mechanisms at atomic scale. In this mini-review, we describe recent advances on the synthesis of heterogeneous catalysts by three different promising methods using vapors of metal or organometallic complexes as precursors: atomic layer deposition (ALD), cluster beam deposition (CBD) and metal vapor synthesis (MVS). Catalytic applications over the last decade of heterogeneous catalysts containing single atoms, clusters or nanoparticles are reported and discussed pointing out the potentiality of these three approaches.

Bulky Cyclometalated Ruthenium Nitrates for Challenging Z-Selective Metathesis: Efficient One-Step Access to α-Oxygenated Z-Olefins from Acrylates and Allyl Alcohols.

α-Oxygenated Z-olefins are ubiquitous in biologically active molecules and serve as versatile handles for organic synthesis, but their syntheses are often tedious and less selective. Here we report the efficient Z-selective metathesis of various terminal acrylates and allyl alcohols, which enables facile and selective construction of high value-added α-oxygenated Z-olefins from readily available feedstock chemicals. These challenging metathesis transformations are enabled by novel cyclometalated Ru-carbene-nitrate complexes bearing bulky-yet-flexible side arms, whose assembly was unlocked by new organometallic syntheses.

Bulky Cyclometalated Ruthenium Nitrates for Challenging Z‐Selective Metathesis: Efficient One‐Step Access to α‐Oxygenated Z‐Olefins from Acrylates and Allyl Alcohols

Abstractα‐Oxygenated Z‐olefins are ubiquitous in biologically active molecules and serve as versatile handles for organic synthesis, but their syntheses are often tedious and less selective. Here we report the efficient Z‐selective metathesis of various terminal acrylates and allyl alcohols, which enables facile and selective construction of high value‐added α‐oxygenated Z‐olefins from readily available feedstock chemicals. These challenging metathesis transformations are enabled by novel cyclometalated Ru‐carbene‐nitrate complexes bearing bulky‐yet‐flexible side arms, whose assembly was unlocked by new organometallic syntheses.

Nickel-Catalyzed Kumada Vinylation of Enol Phosphates: A Comparative Mechanistic Study

Based on supporting stoichiometric organometallic syntheses, structural analyses, reaction monitoring, radical-clock experiments, and kinetic investigations, a comparative mechanistic study between two related systems that are competent in the Ni-catalyzed Kumada cross-coupling reaction between enol phosphates and vinyl magnesium bromide is reported. We demonstrate that the two bisphosphine–nickel complexes operate via Ni(0)/Ni(II) catalytic manifolds for this type of C(sp2)–O electrophiles. The first complex of generic structure [(dppe)NiBr2] is reduced in situ upstream from the productive catalytic cycle, which itself follows a classical mechanistic scenario composed of an oxidative addition/transmetalation/reductive elimination sequence. A rapid phosphate/bromide ion exchange prior to transmetalation constitutes a key feature of this system. The related [(dmpe)NiBr2] complex follows a much less conventional pathway. Kinetic analyses distinguish themselves by an unusual apparent second order in the catalyst, which is attributed to an interplay between vinyl nickel species formed during precatalyst activation and styrenyl nickel intermediates generated downstream in the sequence of elementary steps. This hypothesis is corroborated by independent supporting organometallic investigations.

Recent Advances in Synthesis of Molecular Heteroleptic Osmium and Iridium Phosphorescent Emitters

AbstractThe application of new procedures of organometallic synthesis based on alternative starting complexes has given rise to a significant enhancement in the preparation of osmium(IV), osmium(II), and iridium(III) emitters, since 2012. The choice of the precursors should be done taking into account its ligands, since they may cooperate in the emitter synthesis. Three different functions are clearly pointed out in the revised procedures: the ligands of the starting compounds can direct the selectivity of competitive ruptures of σ‐bonds of the chromophores, without having direct participation in the activation; on the contrary, they can directly participate in the generation of a ligand, being a part of the new coordinated group; and the ligands can also act as internal base in σ‐bond heterolytic activation reactions. In addition, the ability of the polyhydrides OsH6(PiPr3)2 and IrH5(PiPr3)2 to activate C−H bonds is pointed out as one of the determining factors of the success in many cases.

Layered Zinc Hydroxides: Direct Organometallic Synthesis of Carboxylate Intercalated Layered Zinc Hydroxides for Fully Exfoliated Functional Nanosheets (Adv. Funct. Mater. 30/2021)

In article number 2102631, Milo S. P. Shaffer, Charlotte K. Williams, and co-workers present a direct and versatile organometallic route to carboxylate-intercalated layered zinc hydroxide (LZH) 2D nanosheets. The functional LZHs show excellent solubility in polar solvents, including water with solubilities of up to 140 mg mL−1 and monolayer exfoliation yields of 70–80%. This method contrasts with more conventional top-down routes to layered metal hydroxides and offers unique insight into the mechanisms of seeding, growth, and exfoliation of 2D materials.

A Simple, Inexpensive, Mercury-Free Bubbler Apparatus

Inert gas manifolds for the handling of air-sensitive materials are commonplace in the inorganic chemistry curriculum as well as in research laboratories specializing in inorganic and organometallic synthesis. Mercury bubblers are ubiquitously implemented for maintaining a positive internal pressure for air-free manifold systems, commonly known as Schlenk lines. This has rendered them difficult to replace with equivalent and accessible alternatives. This communication describes the setup and implementation of a simple, inexpensive alternative to the traditional mercury bubbler that is modular and flexible enough to fit most any laboratory space.

Direct Organometallic Synthesis of Carboxylate Intercalated Layered Zinc Hydroxides for Fully Exfoliated Functional Nanosheets

AbstractIntercalation of organic anions into 2D materials can enable exfoliation, improve dispersion stability, increase surface area, and provide useful functional groups. In layered metal hydroxides, intercalation of bulk structures is commonly achieved by cumbersome and typically incomplete anion exchange reactions. In contrast, here, a series of carboxylate‐intercalated layered zinc hydroxides (LZH‐R) are synthesized directly, at room temperature, by reacting an organozinc reagent with a precise sub‐stoichiometric quantity of the desired carboxylic acid and water. A range of carboxylic acids are used to make new LZH‐R materials which are crystalline, soluble, and functionalized, as established by X‐ray diffraction, spectroscopic, and microscopy techniques. When R is an alkyl ether carboxylate, this direct synthesis method results in the spontaneous exfoliation of the LZH‐R into monolayer nanosheets with high yields (70–80%) and high solubilities in alcohols and water of up to 180 mg mL−1. By altering the carboxylate ligand, functional groups suitable for post‐synthetic modification or for detection by fluorescence are also introduced. These examples demonstrate a versatile synthetic route for functional exfoliated nanosheets.

Facile Organometallic Synthesis of Fe-Based Nanomaterials by Hot Injection Reaction.

Fe-based colloids with a core/shell structure consisting of metallic iron and iron oxide were synthesized by a facile hot injection reaction of iron pentacarbonyl in a multi-surfactant mixture. The size of the colloidal particles was affected by the reaction temperature and the results demonstrated that their stability against complete oxidation related to their size. The crystal structure and the morphology were identified by powder X-ray diffraction and transmission electron microscopy, while the magnetic properties were studied at room temperature with a vibrating sample magnetometer. The injection temperature plays a very crucial role and higher temperatures enhance the stability and the resistance against oxidation. For the case of injection at 315 °C, the nanoparticles had around a 10 nm mean diameter and revealed 132 emu/g. Remarkably, a stable dispersion was created due to the colloids’ surface functionalization in a nonpolar solvent.

Organometallic synthesis, structural and optical properties of CdSe quantum dots passivated with ternary AgZnS alloyed shell

We report on the surface passivation of a new alloyed ternary AgZnS shell layer on luminescent CdSe quantum dots (QDs) via the organometallic hot-injection pyrolysis of metal precursors, surfactant precursors and organic ligands in a non-coordinating solvent. Transmission electron microscopy, X-ray diffraction, Raman spectroscopy and UV/vis absorption and fluorescence emission spectrophotometry were used to characterize the QD nanocrystals. Fixed AgZnS shell alloying was used as the main fabrication strategy to engineer the band gap of CdSe/AgZnS core/alloyed shell QDs which in turn led to a blended mixture of homogenous and heterogenous particle size growth with spherical, quasi-spherical and trigonal-shaped particles. The crystal structure of CdSe/AgZnS QDs was mainly zinc blende but as the QDs size increased with time, a superimposition of zinc blende and wurtzite hexagonal structure was observed with the former being predominant in the diffraction pattern. The photoluminescence (PL) emission spectra of CdSe/AgZnS QDs were tuned across the visible region while the full width at half maximum was as low as 33 nm, representing an 8 nm decrease compared to 41 nm FWHM exhibited by CdSe QDs. As CdSe/AgZnS core/alloyed shell QDs grew with time, the PL quantum yield (QY) increased from 67% for CdSe to a maximum of ~100% for CdSe/AgZnS QDs and thereafter decreased steadily to a minimum of 36% upon further growth. By achieving ~100% PL QY, it appears that interfacial surface defect states in the core/alloyed shell QDs were completely eliminated via the AgZnS shell alloying process on the CdSe core. The unique optical properties exhibited by CdSe/AgZnS core/alloyed shell QDs as reported in this work shows great promise for light emitting QD applications.

Catalytic Hydrogenation: Organometallic Synthesis of Bimetallic Cobalt‐Rhodium Nanoparticles in Supported Ionic Liquid Phases (CoxRh100−x@SILP) as Catalysts for the Selective Hydrogenation of Multifunctional Aromatic Substrates (Small 5/2021)

Catalytic Hydrogenation: Organometallic Synthesis of Bimetallic Cobalt‐Rhodium Nanoparticles in Supported Ionic Liquid Phases (Co<i>_x</i>Rh₁₀₀₋<i>_x</i>@SILP) as Catalysts for the Selective Hydrogenation of Multifunctional Aromatic Substrates (Small 5/2021)

Nanometallurgy in solution: organometallic synthesis of intermetallic Pd-Ga colloids and their activity in semi-hydrogenation catalysis.

Nanoparticles (NPs) of Pd1--xGax (x = 0.67, 0.5, 0.33), stabilized in non-aqueous colloidal solution, were obtained via an organometallic approach under mild conditions using [Pd2(dvds)3] and GaCp* as all-hydrocarbon ligated metal-precursor compounds (dvds = 1,1,3,3-tetramethyl-1,3-divinyl-disiloxane; Cp* = η5-C5Me5; Me = CH3). The reaction of the two precursors involves the formation of a library of molecular clusters [PdnGamCp*y(dvds)z], as shown by liquid injection field desorption ionization mass spectrometry (LIFDI-MS). Full characterization of the catalytic system (HR-TEM, EDX, DLS, PXRD, XPS, NMR, IR, Raman) confirmed the formation of ultra-small, spherical NPs with narrow size distributions ranging from 1.2 ± 0.2 nm to 2.1 ± 0.4 nm (depending on the Pd : Ga ratio). The catalytic performance of the Pd1--xGax NPs in the semi-hydrogenation of terminal and internal alkynes and the influence of the gallium content on product selectivity were investigated. The highest activities (65%) and selectivities (81%) are achieved using colloids with a "stoichiometric" Pd/Ga ratio of 1 : 1 at 0 °C and 2.0 bar H2 pressure. While lower Ga ratios lead to an increase in activity, higher Ga contents increase the olefin selectivity but are detrimental to the activity.

An air-stable, reusable Ni@Ni(OH)2 nanocatalyst for CO2/bicarbonate hydrogenation to formate.

Production of formate via CO2/bicarbonate hydrogenation using cheap metal-based heterogeneous catalysts is attractive. Herein, we report the organometallic synthesis of a foam-like Ni@Ni(OH)2 composite nanomaterial which exhibited remarkable air stability and over 2 times higher catalytic activity than commercial RANEY® Ni catalyst in formate synthesis. Formate generation was achieved with an optimal rate of 6.0 mmol gcat-1 h-1 at 100 °C, a significantly lower operation temperature compared to the 200-260 °C reported in the literature. Deep characterization evidenced that this nanomaterial was made of an amorphous Ni(OH)2 phase covering metallic Ni sites; a core-shell structure which is crucial for the stability of the catalyst. The adsorption of bicarbonates onto the Ni@Ni(OH)2 catalyst was found to be a kinetically relevant step in the reaction, and the Ni-Ni(OH)2 interface was found to be beneficial for both CO2 and H2 activation thanks to a cooperative effect. Our findings emphasize the underestimated potential of Ni-based catalysts in CO2 hydrogenation to formate, indicating a viable strategy to develop stable, cheap metal catalysts for greener catalytic applications.

Fluorescent Cadmium Chalcogenide Nanoclusters in Ubiquitin

Fluorescent semiconductor nanoclusters (FNCs) have received much attention by many scientists due to their attractive functions and features. However, the traditional organometallic chemical synthesis routes for such FNCs require harsh reaction conditions in organic solvents, which limit their use in biological applications. Therefore, developing synthesis strategies for the fabrication of FNCs by association with proteins under mild reaction conditions is pivotal to improve their functionalities. In addition, understanding the effect of structural and chemical properties of proteins on the synthesis mechanism of FNCs is one of the key points, which eventually enables to control and tune the photophysical properties of FNCs. The purpose of this study is to introduce the syntheses of cadmium selenide nanocluster (CdSeNC) and cadmium sulfide nanocluster (CdSNC) by using ubiquitin, a small cysteine‐free protein, and investigating their properties via spectroscopic and microscopic methods. It is shown that significant changes in the protein structure as well as in its oligomerization occur upon the formation of the highly hydrated FNCs.

Engineering Iron–Nickel Nanoparticles for Magnetically Induced CO2Methanation in Continuous Flow

AbstractInduction heating of magnetic nanoparticles (NPs) is a method to activate heterogeneous catalytic reactions. It requires nano‐objects displaying high heating power and excellent catalytic activity. Here, using a surface engineering approach, bimetallic NPs are used for magnetically induced CO2methanation, acting both as heating agent and catalyst. The organometallic synthesis of Fe30Ni70NPs displaying high heating powers at low magnetic field amplitudes is described. The NPs are active but only slightly selective for CH4after deposition on SiRAlOx owing to an iron‐rich shell (25 mL min−1, 25 mT, 300 kHz, conversion 71 %, methane selectivity 65 %). Proper surface engineering consisting of depositing a thin Ni layer leads to Fe30Ni70@Ni NPs displaying a very high activity for CO2hydrogenation and a full selectivity. A quantitative yield in methane is obtained at low magnetic field and mild conditions (25 mL min−1, 19 mT, 300 kHz, conversion 100 %, methane selectivity 100 %).

Engineering Iron–Nickel Nanoparticles for Magnetically Induced CO2Methanation in Continuous Flow

Induction heating of magnetic nanoparticles (NPs) is a method to activate heterogeneous catalytic reactions. It requires nano-objects displaying high heating power and excellent catalytic activity. Here, using a surface engineering approach, bimetallic NPs are used for magnetically induced CO2 methanation, acting both as heating agent and catalyst. The organometallic synthesis of Fe30 Ni70 NPs displaying high heating powers at low magnetic field amplitudes is described. The NPs are active but only slightly selective for CH4 after deposition on SiRAlOx owing to an iron-rich shell (25 mL min-1 , 25 mT, 300 kHz, conversion 71 %, methane selectivity 65 %). Proper surface engineering consisting of depositing a thin Ni layer leads to Fe30 Ni70 @Ni NPs displaying a very high activity for CO2 hydrogenation and a full selectivity. A quantitative yield in methane is obtained at low magnetic field and mild conditions (25 mL min-1 , 19 mT, 300 kHz, conversion 100 %, methane selectivity 100 %).

European Research in Focus: Mechanochemistry for Sustainable Industry (COST Action MechSustInd)

In this Guest Editorial the recently funded COST Action: CA18112 – Mechanochemistry for Sustainable Industry (MechSustInd) is introduced to the scientific community. The use of mechanical energy to facilitate chemical transformations (mechanochemistry) has been rapidly gaining momentum across diverse areas of science. Experimentally, the strategies to mechanically promote physico-chemical changes in matter are varied and include the use of mechanical milling, extrusion techniques, pulsed ultrasonication, and single-molecule force-spectroscopy approaches, among others. Altogether, the implementation of these experimental techniques has resulted in the discovery of new chemical reactions and in the development of more sustainable alternatives to classical synthetic protocols. Collectively, the renaissance and thriving growth of mechanochemistry with its potential to enhance chemical synthesis have been recently acknowledged by the International Union of Pure and Applied Chemistry (IUPAC).1 Simultaneously, in 2019, one of the most prestigious and influential funding organizations for research and innovation networks in Europe, the European Cooperation in Science and Technology (COST),2 funded the COST Action: CA18112 – Mechanochemistry for Sustainable Industry (MechSustInd).3 This will provide a unique opportunity for scientific and technological growth in the area of mechanochemistry across Europe. As such, we are pleased to celebrate as well as to introduce the MechSustInd COST Action in this Editorial. The first steps towards a successful COST Action have already begun. To date, MechSustInd encompasses partners from 33 COST Member Countries, including 18 Inclusiveness Target Countries and partners, nine companies, one European intergovernmental scientific research organization (European Synchrotron Radiation Facility, ESRF), as well as partners from Canada, China, Mexico, Russia, Singapore, and USA. In total, represented by 72 Academic Institutions across Europe and around the world (Figure 1). During its lifespan, the COST Action CA18112 MechSustInd will enhance the cooperation of scientists already working in the field, but more importantly it will promote the translation of mechanochemistry into alternative niche sectors. For instance, efforts will be devoted to disseminate and train fundamental aspects of mechanochemistry and mechanochemical techniques within higher education and vocational training settings. Additionally, all members of this COST Action CA18112 will aim to develop mechanochemical synthetic routes of value-added products from laboratory-scale set-ups to large-scale production. This quest will be closely accompanied by physico-chemical and computational studies to better understand the mechanistic aspects prevailing in such mechanochemical transformations. Important to the success of implementing mechanochemical protocols in industry is the development of new mechanochemical techniques to complement existing strategies for the activation of reactants by mechanical treatment. More ambitious targets for MechSustInd also lie ahead, namely, the establishment of fruitful multi-disciplinary collaborative networks involving researchers from a myriad of academic institutions and industries. These networks will share the common objective of harmonizing both fundamental and applied research for industrial needs and fostering technological transfer from research laboratories to industrial value chains. Furthermore, to increase the potential impact of this COST Action, we will engage with key stakeholders to gain awareness of the current developments in policy making, business strategies, and societal needs. Moreover, we wish to use this Editorial to encourage proactive participation of all scientists, educators (schools and universities), engineers, industrial partners, policy- and decision-makers, and funding bodies alike to successfully achieve the objectives of COST Action CA18112 MechSustInd. Undoubtedly, vital for the achievement of this COST Action's objectives will be the use of more focused networking programs such as Short-Term Scientific Missions aimed at fostering collaboration via excellent research infrastructures and sharing techniques amongst the members of MechSustInd. Equally important will be the organization of Training Schools to standardize, propagate, and encourage the adoption of good experimental practices across the current and future mechanochemistry scientific community. Hence, established scientists will work together with Early Career Investigators to promote the scientific excellence within the field whilst maintaining gender balance within the network. Overall, we hope that in the upcoming years, the COST Action MechSustInd will become an inflexion point in the expansion, diversification, and establishment of mechanochemistry in a wide range of fields such as organic chemistry, organometallic synthesis, solid-state chemistry, spectroscopy, molecular modeling, process engineering, and crystal engineering, to name a few. Let the coming chemistry years be mechanical! This article is based upon work from COST Action CA18112, supported by COST (European Cooperation in Science and Technology).

Dissecting Transmetalation Reactions at the Molecular Level: Phenyl Transfer in Metal Borate Complexes

Despite the wide use of transmetalation reactions in organic and organometallic synthesis, little is known about the involved intermediates and mechanisms. Here, we use a combination of electrospra...