Metathesis Reaction Research Articles

Self-healing amine- and carboxy-cured bio-based epoxy vitrimers driven by the disulfide metathesis reaction

Self-healing amine- and carboxy-cured bio-based epoxy vitrimers driven by the disulfide metathesis reaction

Gradual spin crossover behavior encompasing room temperature in an iron(II) complex based on a heteroscorpionate ligand.

In this paper, we report the synthesis of six novel triazole-based heteroscorpionate ligands based on heterocycle metathesis reactions and their iron(II) complexes. Single crystal structure analyses were performed, the spectroscopic and magnetic properties of the obtained complexes were studied and their spin crossover-structural relationships were compared to those obtained for their pyrazole-based analogues reported in the literature. In particular, the amino derivative complex bis[hydrobis(pyrazol-1-yl)(3-amino-1,2,4-triazol-1-yl)]iron(II) obtained by post-synthetic catalytic nitro-group reduction under pressure of hydrogen in an autoclave presents a scarce gradual spin crossover behavior at room temperature. The profile of the SCO curve can be explained by the presence of only relatively weak H bonds, spreading only in one dimension. Among the interesting spin transition behaviors observed for the different complexes, such stable, complete and gradual spin crossover at room temperature makes this neutral complex a good candidate for sublimation and future investigation as an active element notably for thermoreflectance-based surface microthermometry applications.

Video Documented Upscaled Synthesis of Salts of the Parent Carbaborate Ion [CB11H12]−, its Undecafluorinated Form [CHB11F11]− and Useful Starting Materials for its Introduction

AbstractIn this work, we present our improved protocols for the single batch syntheses of approximately 32 g of [NHMe3][CB11H12] and 10 g of Na[CHB11F11] as well as salt metathesis reactions, granting access to useful starting materials to introduce the [CHB11F11]− anion. This includes the trityl cation [Ph3C]+ and the bis‐1,2‐difluorobenzene‐silver(I)‐complex [Ag(odfb)2]+, as well as some applications of the shown compounds. The described methodology allows the synthesis of large amounts of both the [CB11H12]− and the [CHB11F11]− anion and therefore making them accessible for further reactions. To facilitate the reproducibility, we present video tutorials of the synthetic steps towards Na[CHB11F11].

Stable Ditriflates of D‐Glucose in the Synthesis of Iminosugars and Polyhydroxylated Pipecolic Acids

AbstractA synthesis of the five membered iminosugar DAB and a divergent synthesis of the six membered iminosugar 1‐dehydromannojirimycin (DMJ) and the corresponding sugar imino acid are reported. They involve double nucleophilic displacements of a D‐xylose ditriflate by benzyl carbazate and a D‐glucose ditriflate by allyl amine, respectively. They are followed by a similar protocol consisting of hydrolysis and oxidation or reduction of the resulting bicyclic glycosides. This allowed DMJ to be obtained from the cheap sugar D‐glucose.

Synthesis and Characterization of Solvated Lanthanide(II) Bis(triisopropylsilyl)phosphide Complexes.

Lanthanide (Ln) silylamide chemistry is well-developed, but the corresponding silylphosphide chemistry is immature; there are only ten structurally characterized examples of Ln(II) bis(trimethylsilyl)phosphide complexes to date and no reported derivatives with bulkier R-groups. Here, we report the synthesis of the first f-block bis(triisopropylsilyl)phosphide complexes, [Ln{P(SiiPr3)2}2(THF)x] (1-Ln; Ln = Sm, Eu, x = 3; Ln = Yb, x = 2), by the respective salt metathesis reactions of parent [LnI2(THF)2] with 2 equiv of [Na{P(SiiPr3)2}]n in toluene. Complexes 1-Ln were characterized by a combination of NMR, EPR, ATR-IR, electronic absorption and emission spectroscopies, elemental analysis, SQUID magnetometry, and single crystal X-ray diffraction. These data contrast with those obtained for related Ln(II) bis(trimethylsilyl)phosphide complexes due to the bulkier ligands in 1-Ln and also with Ln(II) bis(triisopropylsilyl)amide complexes due to a combination of longer Ln-P vs. Ln-N bonds and the softer nature of P- vs. N-donor ligands.

Polyurethane Vitrimers Engineered with Nitrogen-Coordinating Cyclic Boronic Diester Bonds for Sustainable Bioelectronics.

Flexible bioelectronic devices seamlessly interface with organs and tissues, offering unprecedented opportunity for timely prevention, early diagnosis, and medical therapies. However, the majority of flexible substrates utilized in bioelectronics still encounter significant challenges in terms of recyclability and reprocessing, leading to the accumulation of environmentally and biologically hazardous toxic waste. Here, the study reports the design of recyclable polyurethane (PU) vitrimers engineered with internal boron-nitrogen coordination bonds that can reversibly dissociate to boronic acids and hydroxyl, or undergo metathesis reaction following an associative pathway. The study demonstrates the capacity of these recyclable PU vitrimers as flexible substrates in various wearable and implantable bioelectronic applications, achieving high-quality electrophysiological recordings and stimulation. Furthermore, the study establishes a sustainable recycling process by reconstructing a range of bioelectronic devices from the recycled PU vitrimers without compromising the mechanical performance. This closed-loop approach not only addresses the critical challenge of the reclaiming medical electronic waste but also paves the way for the development of sustainable flexible bioelectronics for healthcare applications.

Synthesis and Characterization of Extremely Bulky Aminopyridinate Ligands and a Series of Their Groups 1 and 2 Metal Complexes

High-yielding synthetic routes to five new extremely bulky aminopyridine pro-ligands were developed, viz. (C5H3N-6-Ar1)N(H)Ar2-2; Ar1 = Trip, Ar2 = TCHP (HAmPy1), Ar* (HAmPy2) or Ar† (HAmPy3); Ar1 = TCHP, Ar2 = Ar* (HAmPy4) or Ar† (HAmPy5) (Trip = 2,4,6-triisopropylphenyl, TCHP = 2,4,6-tricyclohexylphenyl, Ar* = C6H2(CHPh2)2Me-2,6,4, Ar† = C6H2(CHPh2)2Pri-2,6,4. Four of these were deprotonated with LiBun in diethyl ether to give lithium aminopyridinate complexes which were dimeric for the least bulky ligand, [{Li(AmPy1)}2] or monomeric for the bulkier aminopyridinates, i.e., in [Li(AmPy2−4)(OEt2)]. One aminopyridine was deprotonated with MeMgI to give monomeric [Mg(AmPy3)I(OEt2)2]. When treated with sodium or potassium mirrors or 5% w/w Na/NaCl, over-reduction occurred, leading to the alkali metal aminopyridinates, [M(AmPy3)(η6-toluene)] (M = Na or K) or [{Na(AmPy3)}∞]. An attempted reduction of [Mg(AmPy3)I(OEt2)2] with a dimagnesium(I) compound led only to partial loss of diethyl ether and the formation of [(AmPy3)Mg(μ-I)2Mg(AmPy3)(OEt2)]. All prepared complexes have potential as ligand transfer reagents in salt metathesis reactions with metal halide complexes.

Modular Synthesis of Monoanionic PN Ligands Leads to Unexpected Structural Diversity in Lanthanum Chemistry.

We report a new synthetic entry to a series of N-substituted anilidophosphine ligands (short HPNR, R = pTol (HPNTol), 3,5-dimethylphenyl (HPN3,5Me), 3,5-bis(trifluoromethyl)phenyl (HPN3,5CF3), 2-methoxyphenyl (HPNOMe), diisopropylphenyl (HPNDipp), and adamantyl (HPNAd)), allowing a detailed tuning of their steric (and electronic) properties. HPNR could be converted into their lithium salts LiPNR, which are effective precursors for salt metathesis reactions. The new ligands are used for the synthesis of an array of lanthanide complexes using LaCl3(THF)1.2 as a precursor. Depending on the steric bulk of the anilidophosphine ligand, either chloride-bridged dimers of the general formula [(PNR)2La(μ-Cl2)La(PNR)2] (R = pTol (3f), 3,5-dimethylphenyl (3d) and adamantyl (3a)) or mononuclear complexes of the general formula (PNR)2LaCl (R = diisopropylphenyl (3e)) are observed, if the complexation reaction is carried out in toluene. Contrary, if salt metathesis reactions are carried out in dimethoxyethane (DME) as a coordinating solvent, -ate complexes of the general formula [(PNR)2La(μ-Cl2)Li(DME)] (R = Adamantyl (4a) and R = 2-methoxyphenyl (4d)) or [Li(DME)3][(PNR)2LaCl2] (R = 3,5-bis(trifluoromethyl)phenyl (4b), R = pTol (4f) and R = 3,5-dimethylphenyl (4d)) are observed. All ligands and complexes have been thoroughly characterized by 1D and 2D NMR spectroscopy, IR, and X-ray crystallography. Finally, the steric demand of the new anilidophosphine ligands is evaluated using SambVca simulations.

Metal-organic frameworks with a sulfur-rich heterocycle: synthesis, gas adsorption properties, and metal exchange.

Three new three-dimensional (3D) metal-organic frameworks [M2(ttdc)2(dabco)] (M = Zn(II), 1-Zn; Cu(II), 1-Cu; and Zn/Cu, 1-ZnCu) based on thieno[3,2-b]thiophene-2,5-dicarboxylate (ttdc2-) were synthesized and characterized by a combination of physicochemical methods (single crystal X-ray diffraction, powder X-ray diffraction, chemical and thermogravimetric analyses and IR spectroscopy). 1-Cu demonstrated permanent porosity (Vpore = 0.790 cm3 g-1 and SBET = 1725 m2 g-1) and significant CO2, CH4, C2H2, C2H4 and C2H6 gas uptakes under ambient conditions. The adsorption selectivities for gas mixtures, calculated by IAST, were 10.8 (10.7), 14.6 (9.4), 1.7 (1.6) and 1.5 (1.6) for the equimolar gas mixture compositions CO2/N2, C2H6/CH4, C2H6/C2H4 and C2H6/C2H2 at 1 bar and 273 K (298 K), respectively. The mixed-metal compound 1-ZnCu was prepared by a crystal-to-crystal ion exchange metathesis reaction from 1-Zn with a 52% degree of ion substitution, confirmed by energy-dispersive X-ray spectroscopy, optical microscopy and single crystal X-ray diffraction analysis.

Cyclization Strategies in Carbonyl–Olefin Metathesis: An Up-to-Date Review

The metathesis reaction between carbonyl compounds and olefins has emerged as a potent strategy for facilitating swift functional group interconversion and the construction of intricate organic structures through the creation of novel carbon–carbon double bonds. To date, significant progress has been made in carbonyl–olefin metathesis reactions, where oxetane, pyrazolidine, 1,3-diol, and metal alkylidene have been proved to be key intermediates. Recently, several reviews have been disclosed, focusing on distinct catalytic approaches for achieving carbonyl–olefin metathesis. However, the summarization of cyclization strategies for constructing aromatic heterocyclic frameworks through carbonyl–olefin metathesis reactions has rarely been reported. Consequently, we present an up-to-date review of the cyclization strategies in carbonyl–olefin metathesis, categorizing them into three main groups: the formation of monocyclic compounds, bicyclic compounds, and polycyclic compounds. This review delves into the underlying mechanism, scope, and applications, offering a comprehensive perspective on the current strength and the limitation of this field.

Iodine-Catalyzed Carbonyl-Alkyne Metathesis Reactions.

The reaction between aldehydes or ketones and alkynes-the carbonyl-alkyne metathesis-constitutes a very useful strategy for the synthesis of α,β-unsaturated carbonyls. We now demonstrate that iodine is a highly efficient catalyst for both the intra- and intermolecular metathesis reaction in very small concentrations (0.1-1 mol %). Our protocol outperforms other catalytic systems, is operationally very simple, cheap, metal-free, and tolerates a large variety of functional groups (e. g., -CN, -CO2Me, -Br, -OH) at very low catalyst loadings. We can furthermore show that iodine-catalyzed carbonyl-alkyne metatheses can be combined with other iodine-catalyzed reactions in one-pot procedures to afford larger and more complex molecular structures. Finally, our mechanistic studies indicate that the iodonium ion is the active catalyst under the reaction conditions.

Novel Silicate Platform as Weakly-Coordinating Anions for Diverse Organometallic and Electrochemical Applications.

Weakly-coordinating anions (WCAs) are employed in a wide range of applications, but limitations remain, including high reactivity, limited redox window, complicated synthesis, high cost, low solublity, and low structural tunabililty. Herein, we report a new class of WCA based onalkyl or aryl (R)substitutedsilicates bearingfluorinated pinacolate ligands,"[RSiF24]-".Anions bearing a variety of R groups were prepared, enabling facile tuning of sterics and solubility. A range of cations employed in chemical reactivity has been supported by these anions, including ether-free alkali cations, Ag+, Ph3C+, Fc+, [NiI(COD)2]+. [Pd(dppe)(NCMe)Me]+has been generated by salt metathesis or protonation of a metal-alkyl bond, showcasing the ability of theRSiF24-anions to support applications in coordination chemistry and catalysis. Electrochemical studies on the [Bu4N]+variant show an exceptionally wide stability window for theMeSiF24-anion of 7.5 V in MeCN. CV experiments demonstrate reversible Mg deposition and stripping.

Novel Silicate Platform as Weakly‐Coordinating Anions for Diverse Organometallic and Electrochemical Applications

Weakly‐coordinating anions (WCAs) are employed in a wide range of applications, but limitations remain, including high reactivity, limited redox window, complicated synthesis, high cost, low solublity, and low structural tunabililty. Herein, we report a new class of WCA based on alkyl or aryl (R) substituted silicates bearing fluorinated pinacolate ligands, "[RSiF24]‐". Anions bearing a variety of R groups were prepared, enabling facile tuning of sterics and solubility. A range of cations employed in chemical reactivity has been supported by these anions, including ether‐free alkali cations, Ag+, Ph3C+, Fc+, [NiI(COD)2]+. [Pd(dppe)(NCMe)Me]+ has been generated by salt metathesis or protonation of a metal‐alkyl bond, showcasing the ability of the RSiF24‐ anions to support applications in coordination chemistry and catalysis. Electrochemical studies on the [Bu4N]+ variant show an exceptionally wide stability window for the MeSiF24‐ anion of 7.5 V in MeCN. CV experiments demonstrate reversible Mg deposition and stripping.

Preparation of poly(endo-norbornene derivatives) with ultra-high molecular weight by combining ROMP and acyclic metathesis reaction

Endo-norbornene derivatives are much cheaper and more accessible. However, it is difficult to prepare endo-polynorbornenes with ultra-high molecular weight (UHMW) by ring opening metathesis polymerization (ROMP) owing to the low activity. The molecular weight of poly(endo-NB-2OH)n could only reach to 309.1 kg mol−1 for 24 h via ROMP. While, UHMW poly(endo-NB-2OH)m was prepared by combining ROMP and acyclic metathesis reaction in much shorter time. The effects of residual monomer, amount of H2SO4, concentration, temperature and reaction time were investigated in depth. The UHMW P(endo-NB-2OH)m (Mn =2645.5 kg mol−1, PDI = 1.74) could be obtained at 80 °C for 5 min with H2SO4/G3 as 10/1 and concentration of 0.1 M. Moreover, UHMW P(endo-NBI-OH)m(Mn =1114.2 kg mol−1, PDI = 1.95) was also successfully prepared by this method. However, the H2SO4/G3 should increase to 30/1, and reacted for 45 min owing to the steric resistance of the cyclic dicarboximide. For P(exo-NBI-OH)n with lower activity, reaction time should prolong to 3 h to obtain UHMW P(exo-NBI-OH)m(Mn =1716.7 kg mol−1, PDI = 1.93). Finally, UHMW P(endo-NB-2alkyne)m, P(endo-NBI-alkyne)m, and P(exo-NBI-alkyne)m were successfully prepared via post-modification. Acyclic metathesis reaction is a robust and universal reaction to prepare other functional UHMW polynorbornenes, especially for the UHMW endo-polynorbornenes, which could not be prepared by ROMP efficiently.

Stabilization and Surface Functionalization of Palladium Disulfide Nanoparticles with Acetylene Derivatives.

Metal chalcogenide nanoparticles have been attracting extensive attention in diverse fields. Traditionally these nanoparticles are stabilized by organic ligands such as thiols and amines involving nonconjugated core-ligand interfacial interactions. In the present study, a facile wet-chemistry method is described for the synthesis of palladium disulfide (PdS2) nanoparticles capped with acetylene derivatives. Spectroscopic and electrochemical measurements suggest that conjugated Pd-C≡ linkages are formed at the core-ligand interface and facilitate electronic coupling and hence manipulation of the nanoparticle optical and electronic properties. The unique interfacial linkages also allow further functionalization of the nanoparticles by metathesis reaction with olefin derivatives, as manifested in the reaction with vinylferrocene. This research opens new avenues for the structural engineering and functionalization of metal chalcogenide nanoparticles.

Study on fracture behaviour of pipeline girth welds based on curved wide plate specimens: Experimental and numerical analysis

Understanding the fracture characteristics and strain capacity of pipelines with girth welds under external loads is crucial for evaluating pipeline safety. The use of curved wide plate (CWP) specimens closely resembling full-scale (FS) pipelines in geometry provides a more realistic representation of crack tip constraint states compared to small-size fracture toughness test specimens in laboratory settings. This study aims to investigate the ductile fracture characteristics of center cracks on the outer surface of girth welds in high-grade steel pipelines under external loads through large-scale CWP tensile tests and advanced numerical simulations. Tensile tests were conducted on CWP specimens using a kiloton tensile testing machine, with double crack opening displacement (COD) gauge monitoring crack mouth opening displacement (CMOD), and high-precision displacement sensors and strain gauges tracking deformation and strains at various positions. The study yielded significant experimental results, and a finite element (FE) model of the CWP was developed using the nonlinear finite element method (FEM) to validate the experimental data against simulation results. The FE model was then used to investigate the influence of material properties on crack propagation resistance and driving force curves. A method for determining the ultimate tensile strain capacity (UTSC) of pipelines based on actual material fracture toughness was proposed. This research contributes valuable experimental data for further exploration of fracture behaviour in large-scale pipeline girth welds and offers insights for safety evaluations of such welds.

High-Yield Synthesis Route, Post-Synthesis Treatment, and Insights into the Photoluminescence and Magnetic Properties of Tricopper(I) Melaminate Cu3(C3N6H3).

A novel and more efficient synthesis of Cu3(C3N6H3) is presented through a salt-metathesis reaction using copper(I) chloride and sodium hydrogen cyanamide. This synthesis yields a melaminate trianion through the cyclotrimerization of (HNCN)- ions, offering an alternative route to the deprotonation of melamine for synthesizing melaminate. The reaction is analyzed via differential thermal analysis. After the unconventional formation of this MOF-like structure by solid-state reaction, this material still requires treatment via solvent exchange and vacuum drying due to the presence of a host molecule inside the channels of the structure. The process and the impact of the treatment of Cu3(C3N6H3) on its XRD pattern are thoroughly discussed. Additionally, results from stability, NMR and infrared spectroscopy, and thermogravimetric analysis. Finally, photoluminescence and magnetic studies are conducted to evaluate their potential as a functional material.

Slow Magnetic Relaxation in a Dysprosium Metallocene Complex Bearing Equatorial DyIII‐P Bonds

Single molecule magnets (SMMs) containing dysprosium‐phosphorus bonding are rare due to great challenges in constructing the bonding between hard lanthanide ions and soft phosphorus donors. Here we successfully isolated a novel mononuclear bis‐Cp* dysprosium compound, Cp*2Dy[η‐CH(PPh2)2]·C7H8 (1‐Dy), via the salt metathesis reactions of Cp*2Dy(BPh4) and K[(PPh2)2CH] in THF (Cp* = pentamethylcyclopentadienyl). The magnetic investigations indicate its strong SMM behavior evidenced by the open magnetic hysteresis loops below 6 K and the high effective barrier of 300 cm‐1. This could be ascribed to weak dative DyIII‐P bonds at equatorial sites in such [Cp2DyX]‐type (X = auxiliary donors) complexes.

Boosting the Efficiency and Stability of Li-CO2 Batteries via a Ruthenium-Based Olefin-Metathesis Catalyst.

The practical application of Li-CO2 batteries is significantly hindered by high charge potential and short lifespan, mainly due to sluggish reaction kinetics and inadequate reaction reversibility. Homogeneous catalysts added to the electrolyte provide a promising strategy to address these issues. In this work, the third-generation Grubbs catalyst (G-III), which is efficient for olefin metathesis reactions, has been adopted as a homogeneous catalyst for Li-CO2 batteries. Batteries with G-III exhibited a low overpotential of 0.86 V and a lifespan of 1300 h at a current density of 300 mA g-1. Even at a high current density of 2000 mA g-1, the batteries remained stable for over 300 cycles, with an initial overpotential of 1.11 V. A two-step discharge/charge reaction involving Li2C2O4 as an intermediate was well illustrated, attributed to both low overpotentials and high specific capacity. These findings provide insights into catalyst selection and mechanism analysis for Li-CO2 batteries, offering practical strategies for Li-CO2 battery performance enhancement and practical applications.

Rhodesain inhibitors on the edge of reversibility-irreversibility

A comparative study of Michael acceptor and keto-Michael acceptor inhibitors of the cysteine protease rhodesain has been performed. Five new inhibitors have been prepared bearing the peptide structure of the known cysteine protease inhibitor K11777 and differing on the warhead. For the preparation of the Michael acceptor warhead, a Horner-Wadsworth-Emmons reaction was used. In the synthetic routes of the keto-Michael acceptor warheads, keto-enoate and keto-vinyl sulfone, a metathesis reaction and a radical sulfonylation were the key steps, respectively. Interestingly, keto-Michael acceptors inhibited rhodesain through a dual mode of action, showing reversibility at low inhibitor concentrations and irreversibility at high inhibitor concentrations.