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The effects of hydrogen absorption on the local lattice structure in palladium (Pd) were investigated by means of positron annihilation lifetime spectroscopy (PALS) and time-differential perturbed angular correlation (TDPAC) spectroscopy. The PALS measurements demonstrated that dislocations and vacancies formed in the preparation process of a pristine Pd plate can be clearly removed by vacuum annealing at 1073 K and the subsequent absorption of a large quantity of hydrogen, resulting in the production of the β-phase hydride PdH0.62, induces the formation of the open-volume defects again. It was also found that the absorbed hydrogen atoms remain in the Pd sample at 323 K but they are completely evacuated during 5 h heating at 383 K. In addition to the overall thermal behavior, an atomic scale observation of the hydrogen dynamics was carried out by means of TDPAC spectroscopy, indicating the nuclear quadrupole relaxation of the present (111m,111Pd → 111Ag→)111Cd probe, which evidently suggests that the hydrogen atoms show fast dynamic motion around the probe. From the temperature-dependent nuclear quadrupole relaxation rate, we obtained an activation energy of 41(4) meV for the motion. [ABSTRACT FROM AUTHOR]

Palladium-encapsulated covalent organic frameworks (Pd/COFs) have garnered enormous attention in heterogeneous catalysis. However, the dominant ex situ encapsulation synthesis is tedious (multistep), time-consuming (typically 4 days or more), and involves the use of noxious solvents. Here we develop a mechanochemical in situ encapsulation strategy that enables the one-step, time-efficient, and environmentally benign synthesis of Pd/COFs. By ball milling COF precursors along with palladium acetate (Pd(OAc)2) in one pot under air at room temperature, Pd/COF hybrids were readily synthesized within an hour, exhibiting high crystallinity, uniform Pd dispersion, and superb scalability up to gram scale. Moreover, this versatile strategy can be extended to the synthesis of three Pd/COFs. Remarkably, the resulting Pd/DMTP-TPB showcases extraordinary activity (96-99% yield in 1 h at room temperature) and broad substrate scope (>10 functionalized biaryls) for the Suzuki-Miyaura coupling reaction of aryl bromides and arylboronic acids. Furthermore, the heterogeneity of Pd/DMTP-TPB is verified by recycling and leaching tests. The mechanochemical in situ encapsulation strategy disclosed herein paves a facile, rapid, scalable, and environmentally benign avenue to access metal/COF catalysts for efficient heterogeneous catalysis.

Palladium is one of the most important technological materials, yet its phase diagram remains poorly understood. At ambient conditions, its solid phase is face-centered cubic (fcc). However, another solid phase of Pd, body-centered cubic (bcc), was very recently predicted in two independent theoretical studies to occur at high pressures and temperatures. In this work, we report an experimental study on the room-temperature equation of state (EOS) of Pd to a pressure of 80 GPa, as well as a theoretical study on the phase diagram of Pd including both fcc-Pd and bcc-Pd. Our theoretical approach consists in ab initio quantum molecular dynamics (QMD) simulations based on the Z methodology which combines both direct Z method for the simulation of melting curves and inverse Z method for the calculation of solid–solid phase transition boundaries. We obtain the melting curves of both fcc-Pd and bcc-Pd and an equation for the fcc–bcc solid–solid phase transition boundary as well as the thermal EOS of Pd which is in agreement with experimental data and QMD simulations. We uncover the presence of another solid phase of Pd on its phase diagram, namely, random hexagonal close-packed (rhcp), and estimate the location of the rhcp-bcc solid–solid phase transition boundary and the rhcp–fcc–bcc triple point. We also discuss the topological similarity of the phase diagrams of palladium and silver, the neighbor of Pd in the periodic table. We argue that Pd is a reliable standard for shock-compression studies and present the analytic model of its principal Hugoniot in a wide pressure range. [ABSTRACT FROM AUTHOR]

The optical spectra of the palladium monosulfide (PdS) molecule in gas phase have been investigated for the first time through laser-induced fluorescence (LIF) and single-vibronic-level (SVL) emission spectroscopies. The I3Σ− − X3Σ− transition system containing 16 vibronic bands was identified in the LIF spectra, covering the energy range of 22 030–23 400 cm−1. The spectra with rotational resolution allowed for the determination of the molecular constants in both the ground X and excited I electronic states, involving the spin–orbit splitting, rotational constant, vibrational frequency, and isotope shift. Isotopically resolved SVL emission spectra permitted the observation of the spin–orbit splitting, vibrational frequency, and vibrational isotope shift of the X3Σ−0+,1 and A3Π2,1,0−,0+ states as they transitioned from the excited I state to the vibrational levels of the X and A states. Ab initio calculations presented plenty of the Λ-S and Ω states of PdS below 28 000 cm−1 and provided strong support for the assignments of the experimental observation. [ABSTRACT FROM AUTHOR]

Developing cost-effective and high-performing bifunctional electrocatalysts is pivotal for advancing rechargeable zinc-air batteries (ZABs). In this study, a Pd–Co₃O₄ loaded on acetylene black (Pd–Co₃O₄/C) electrocatalyst was developed with excellent properties for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) using reduced H₂PdCl₄ to modify Co₃O₄/C. The experimental findings indicate that the Pd–Co₃O₄/C electrocatalyst exhibits a favorable half-wave potential for ORR at 0.91 V, a feasible potential for OER at 1.48 V (measured at 10 mA/cm2), also minor Tafel slopes for both ORR (44.65 mV/dec) and OER (58.41 mV/dec). Additionally, it evidences a power density of 186 mW/cm2 in ZABs and good durability during galvanostatic charge-discharge cycling. The impressive performance of Pd–Co₃O₄/C can be ascribed primarily to the beneficial synergistic effect resulting from the composition of Co₃O₄ and Pd embedded within graphite carbon. This research lays the groundwork for the expansion of additional cost-effective and highly effective electrocatalysts in the coming years. [Display omitted] • Pd-Co₃O₄/C as a bifunctional oxygen electrocatalyst was developed. • Pd-Co₃O₄/C achieves 1.02 V onset potential vs. RHE and 290 mV overpotential at 10 mA/cm² current density. • Pd-Co₃O₄/C shows exceptional cyclic stability at high current density due to high electron transfer and synergistic effects. [ABSTRACT FROM AUTHOR]

In light of the burgeoning biological applications associated with xanthones, the development of highly efficient synthetic methodologies for their production has emerged as a pivotal objective of chemical research. Amidst the array of available protocols, the oxidative carbonylation of diaryl ethers with carbon monoxide (CO) stands out as a notably uncomplicated route, often necessitating stoichiometric oxidants. Herein, we present a feasible approach employing unsymmetrical-waveform alternating current (AC) electrolysis to facilitate Pd-catalysed oxidative C–H/C–H carbonylation. Leveraging a straightforward catalytic system, we demonstrate the conversion of diverse diaryl ethers into xanthones with moderate to commendable yields. Our mechanistic investigations illuminate the indispensable role played by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in the electrochemical system, particularly its ability to recycle heterogeneous palladium species within the solution. [ABSTRACT FROM AUTHOR]

The first stereodivergent umpolung 1,5-conjugate addition reaction via synergistic Pd/Cu catalysts is reported. By dictating the absolute configuration of each chiral ligand ligated to corresponding metals, all four stereoisomers of the products are easily achieved. A series of amino acid moieties are introduced to the γ-position of the conjugated esters in high yields with excellent diastereoselectivities and enantioselectivities. The downstream transformations highlight the synthetic value of the method. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A regiodivergent synthesis of azetidines, 5,6‐dihydro‐1,3‐oxazines and 2,3‐dihydro‐1,4‐oxazines has been achieved through palladium‐catalyzed tandem allylic substitution reaction. This protocol provides a variety of heterocycles in satisfactory yields with good to excellent regioselectivities under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Herein, we have demonstrated a palladium‐catalyzed γ‐alkenylation of unactivated alkenes with vinylcyclopropanes. A bidentate 8‐aminoquinoline directing group was utilized for the regioselective γ‐C(alkenyl)−H functionalization of unactivated alkenes with vinylcyclopropanes. This protocol exhibits wide substrate scope and good selectivity. Additionally, substrate diversification was performed to demonstrate the synthetic utility of the protocol. Mechanistic investigations were carried out to provide an insight to the reaction mechanism. A plausible mechanism was also proposed for the present methodology. [ABSTRACT FROM AUTHOR]

(−)-Cylindrocyclophane A is a 22-membered C2-symmetric [7.7]paracyclophane that bears bis-resorcinol functionality and six stereocenters. We report a synthetic strategy for (−)-cylindrocyclophane A that uses 10 C−H functionalization reactions, resulting in a streamlined route with high enantioselectivity and efficiency (17 steps). The use of chiral dirhodium tetracarboxylate catalysis enabled the C–H functionalization of primary and secondary positions, which was complemented by palladium-catalyzed C(sp2)–C(sp2) cross-couplings, resulting in the rapid formation of the macrocyclic core and all stereocenters with high regio-, diastereo-, and enantioselectivity. The use of a late-stage palladium-catalyzed fourfold C(sp2)–H acetoxylation installed the bis-resorcinol moieties. This research exemplifies how multilaboratory collaborations can produce substantial modernizations of complex total synthesis endeavors. [ABSTRACT FROM AUTHOR]

An enantioconvergent palladium‐catalyzed Negishi cross‐coupling with racemic secondary organozinc reagents has been developed, enabling access to enantioenriched 1,1‐diarylalkane motifs in high yields and enantioselectivities. Computational data indicates that the racemization of organozinc compounds most likely occurs through a bridged bimolecular mechanism. [ABSTRACT FROM AUTHOR]

The power and ability of catalysis to build multiple C−C bonds in a single step has had a transformative impact on organic synthesis. While the reactivity of organohalides with metal catalysts is widely appreciated, the related and more intricate reactivity of acid chlorides is less so, despite their use as common reagents in synthesis. Here, we review the transformations of acid chlorides in combination with unsaturated C−C bonds catalyzed by palladium, rhodium, or iridium and provide an outlook for future research opportunities. [ABSTRACT FROM AUTHOR]

A highly sensitive fluorescence sensor for monitoring low concentrations of hydrogen peroxide was designed. The sensor employs the commercially available palladium or platinum metal on activated charcoal as catalysts to decompose hydrogen peroxide into water and molecular oxygen. The produced oxygen concentration can be measured in real time using an oxygen-sensitive layer doped with photostable oxygen probes. The sensor exhibits high sensitivity that is able to measure hydrogen peroxide concentration down to 20 ppb and can measure hydrogen peroxide concentration in the range of 0.1–100 ppm and 0.02–100 ppm, respectively. The response is fully reversible and the typical response time is less than one minute, which makes it suitable to continuously measure hydrogen peroxide over a long duration. Due to the excellent batch-to-batch consistency of palladium or platinum metal on activated charcoal, the sensor can be massively produced with good reproducibility and affordable price, which holds great potential for constructing sensors for industrial and practical applications. [ABSTRACT FROM AUTHOR]

The synthetic potential of substituted 1,4‐dioxenes is well recognised, although the chemistry of 2‐aryl‐1,4‐dioxenes is relatively unexplored. Their transition metal‐catalysed synthesis has been limited to Stille‐type cross‐coupling chemistry, typically showing long reaction times, or proceeding at high reaction temperatures. Here we present a facile and general methodology for the cross‐coupling of aryl bromides with lithium 1,4‐dioxene, affording a range of 2‐aryl‐1,4‐dioxenes in generally good yields. We highlight the synthetic applicability of this transformation at multigram scale, and demonstrate the versatility of the products by conversion of the dioxene units to various carbonyl‐based functionalities. Additionally, we present a concise two‐step synthesis of an arylated analogue to a known 1,4‐dioxene‐based antifungal agent. [ABSTRACT FROM AUTHOR]

An efficient and cost‐effective Cu (I) mediated protocol for the C(sp2)–C(sp) cross‐coupling of 3‐chalcone‐2‐chloroquinoline with terminal alkynes has been disclosed by optimizing a wide range of catalysts, ligands, base, and solvents. This approach conveniently assembles various alkynylated hybrids with excellent to moderate yields. Appropriate functional group tolerance and significant mechanistic pathway with mild reaction conditions well‐justified this synthetic transformation more sustainable towards the greener exploration. [ABSTRACT FROM AUTHOR]

Membrane‐based gas separation offers notable energy efficiency benefits for hydrogen purification, yet it is often hindered by the inherent trade‐off between permeability and selectivity. To address this challenge, a novel mixed matrix membrane (MMM) design is presented to boost H2 separation performance via continuous hydrogen spillover mechanisms for the first time. The MMM incorporates a palladium‐functionalized ZIF‐67 gel (Pd@ZIF‐67 gel) network into a polymer of intrinsic microporosity (PIM‐1) matrix. The ZIF‐67 gel network serves as a uniform dispersion medium for palladium nanoparticles (Pd NPs), thereby generating a multitude of active sites. These exposed sites, in conjunction with the microporous structure of ZIF‐67, facilitate hydrogen dissociation and establish a continuous hydrogen spillover pathway throughout the membrane. This synergistic MMM design leads to substantial improvements in both hydrogen transport and selectivity. At an optimal loading of 28 wt% Pd@ZIF‐67 gel, the MMMs exhibit a H2 permeability of 3620 Barrer and a remarkable 417% enhancement in H2/CH4 selectivity (24.9), surpassing the 2008 upper bound. This approach paves the way for the development of advanced materials tailored for gas separation applications. [ABSTRACT FROM AUTHOR]

Here, we report a strategy enabling triple switchable chemo‐, regio‐, and stereodivergence in newly developed palladium‐catalyzed cycloadditions of allenes. An asymmetric pseudo‐stereodivergent cycloaddition of allenes bearing a primary leaving group at the α‐position, where a dynamic kinetic asymmetric hydroalkoxylation of racemic unactivated allenes was the enantio‐determining step, is realized, providing four stereoisomers [(Z,R), (Z,S), (E,S), and (E,R)] containing a di‐substituted alkene scaffold and a stereogenic center. By tuning reaction conditions, a mechanistically distinctive cycloaddition is uncovered selectively with the same set of substrates. By switching the position of the leaving group of allenes, a cycloaddition involving an intermolecular O‐attack is disclosed. Diverse mechanisms of the cycloaddition reactions of allenes enable rapid access to structurally and stereochemically diverse 3,4‐dihydro‐2H‐1,4‐benzoxazines in high efficiency and selectivity. [ABSTRACT FROM AUTHOR]

Combining Pd with oxophilic species and appropriate catalyst supports is regarded as an effective approach to strengthen the intrinsic electrocatalytic performance of ethanol oxidation reaction (EOR). In this work, palladium nanocrystals (NCs) modified with Bi (OH) 3 were successfully immobilized on the three-dimensional nitrogen-doped graphene (Pd–Bi(OH) 3 /NG) via a simple one-pot route. The resulting Pd–Bi(OH) 3 /NG demonstrates exceptional electrocatalytic performance for EOR under alkaline conditions, exhibiting enhanced mass and specific activity, kinetics, durability and long-term stability, significantly surpassing that of commercial Pd/C. Notably, the electrocatalytic performance of Pd–Bi(OH) 3 /NG-2 (with an atomic ratio of Pd/Bi at 7:1) is the best among all the tested electrocatalysts. The results reveal that the improved electrocatalytic activity of Pd–Bi(OH) 3 /NG may stem from the significant contributions of the Bi(OH) 3 species decorating of the Pd NCs and their incorporation into the nitrogen-doped graphene. • Pd NCs with surface decoration of Bi(OH) 3 species anchored on NG was firstly fabricated. • The Pd–Bi(OH) 3 /NG achieves a superior electrocatalytic performance for alkaline EOR. • The exciting EOR behavior is owing to surface decoration of Bi(OH) 3 around Pd NCs. • The exciting EOR behavior is also derive from the embedding into NG. [ABSTRACT FROM AUTHOR]

Asymmetric de novo synthesis of benzocyclobutenes (BCBs) via catalytic intermolecular reaction is highly desired for efficient access to this important class of compounds, yet such a strategy remains unmet challenge. Here, we report a Pd/Pyrox‐catalyzed asymmetric [2+2] annulation between arylboronic acids and functionalized alkenes, providing an unprecedented efficient protocol to access various enantio‐enriched BCBs in a modular and versatile manner under mild conditions. A broad substrate scope with excellent enantioselectivity has been achieved under the current protocol. The isolation and characterization of the key chiral palladacycle intermediate, together with DFT calculations, provides strong evidence for the catalytic pathway including an enantiodetermining arylpalladation step. [ABSTRACT FROM AUTHOR]

The phosphinito–phosphinous acid ligand (PAP) is a singular bidentate-like self-assembled ligand exhibiting dissymmetric but interchangeable electronic properties. This unusual structure has been used for the generation of active palladium hydride through alcohol oxidation. In this paper, we report the first theoretical highlight of the adaptative modulation ability of this ligand within a direct H-abstraction path for Pd and Pt catalyzed alcohol oxidation. A reaction forces study revealed rearrangements in the ligand self-assembling system triggered by a simple proton shift to promote the metal hydride generation via concerted six-center mechanism. We unveil here the peculiar behavior of the phosphinito–phosphinous acid ligand in this catalysis. [ABSTRACT FROM AUTHOR]

Pulsed current has proven to be a promising alternative to direct current in electrochemical deposition, offering numerous advantages regarding deposit quality and properties. Concerning the electrodeposition of metal alloys, the role of pulsed current techniques may vary depending on the specific metals involved. We studied an innovative tin–ruthenium electroplating bath used as an anti-corrosive layer for decorative applications. The bath represents a more environmentally and economically viable alternative to nickel and palladium formulations. The samples obtained using both direct and pulsed currents were analyzed using various techniques to observe any differences in thickness, color, composition, and morphology of the deposits depending on the pulsed current waveform used for deposition. [ABSTRACT FROM AUTHOR]

Atomic-scale structures that account for the acceleration of reactivity by heterogeneous catalysts often form only under reaction conditions of high temperatures and pressures, making them impossible to observe with low-temperature, ultra-high-vacuum methods. We present velocity-resolved kinetics measurements for catalytic hydrogen oxidation on palladium over a wide range of surface concentrations and at high temperatures. The rates exhibit a complex dependence on oxygen coverage and step density, which can be quantitatively explained by a density functional and transition-state theory-based kinetic model involving a cooperatively stabilized configuration of at least three oxygen atoms at steps. Here, two oxygen atoms recruit a third oxygen atom to a nearby binding site to produce an active configuration that is far more reactive than isolated oxygen atoms. Thus, hydrogen oxidation on palladium provides a clear example of how reactivity can be enhanced on a working catalyst. [ABSTRACT FROM AUTHOR]

An allylic side chain is introduced onto a chiral γ-amino-β-ketoamide by a Pd-catalyzed allylic alkylation. Subsequent ozonolysis and oxidation proceed only with Cbz-protected ketoamides. The total synthesis of moiramide B is finalized by peptide coupling. [ABSTRACT FROM AUTHOR]

Palladium-catalyzed asymmetric [3+2] cycloaddition reaction of vinyl cyclopropane and electron-deficient dienes was realized. The cycloaddition reaction proceeded regioselectively on the distant C=C double bond of electron-deficient dienes, and was mainly controlled by the steric hindrance of the 5-substituent of electron-deficient dienes. Chiral multi-substituted cyclopentanes bearing three functional groups (monosubstituted alkene, conjugated ester, and cyano) and three continuous stereocenters were obtained in moderate to high yields, diastereoselectivities, and enantioselectivities. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pd/DUT-67-PZDC(10) catalyst with highly dispersed Pd NPs was prepared. • The hierarchically microporous structural property of the DUT-67-PZDC support is beneficial for the stabilization of Pd NPs. • The dual N sites on the DUT-67-PZDC(10) support could act as excellent proton buffers to stimulate the O-H bond cleavage in FA. • The ultrasmall size (1.7 nm) and high dispersion of Pd NPs could expose more catalytic active sites. • The Pd/DUT-67-PZDC(10) catalyst shows an initial TOF value of 2572h−1, 100 % FA conversion and H 2 selectivity, and excellent stability at 60 °C. The highly dispersed ultrasmall palladium nanoparticles (Pd NPs) (1.7 nm) were successfully immobilized on a N -containing metal–organic framework (MOF, DUT-67-PZDC) using a co-reduction method, and it is used as an excellent catalyst for formic acid dehydrogenation (FAD). The optimized catalyst Pd/DUT-67-PZDC(10, 10 wt% Pd loading) shows 100% hydrogen (H 2) selectivity and formic acid (FA) conversion at 60 °C, and the commendable initial turnover frequency (TOF) values of 2572 h−1 with the sodium formate (SF) as an additive and 1059 h−1 even without SF, which is better than most reported MOF supported Pd monometallic heterogeneous catalysts. The activation energy (Ea) of FAD is 43.2 KJ/mol, which is lower than most heterogeneous catalysts. In addition, the optimized catalyst Pd/DUT-67-PZDC(10) maintained good stability over five consecutive runs, demonstrating only minimal decline in catalytic activity. The outstanding catalytic performance could be ascribed to the synergistic corporations of the unique structure of DUT-67-PZDC carrier with hierarchical pore characteristic, the metal-support interaction (MSI) between the active Pd NPs and DUT-67-PZDC, the highly dispersed Pd NPs with ultrafine size serve as the catalytic active site, as well as the N sites on the support could act as the proton buffers. This work provides a new paradigm for the efficient H 2 production of FAD by constructing highly active heterogeneous Pd-based catalysts using MOF supports. [ABSTRACT FROM AUTHOR]

Copyright of Precious Metals / Guijinshu is the property of Precious Metals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Precious Metals / Guijinshu is the property of Precious Metals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Carbopalladation‐initiated cascade reaction involving 1,4‐Pd migration is a straightforward and powerful approach to activate remote C─H bond, forging versatile fused polycyclic compounds containing fluorene fragment which are highly valuable synthetic targets. However, its asymmetric variants pose considerable challenges and have not been explored. Here the first asymmetric palladium‐catalyzed tandem carbopalladation is reported, 1,4‐Pd migration reaction of ortho‐iodophenol‐derived allyl ether under mild conditions, allowing the transformation of a wide range of substrates in good to excellent enantioselectivities, and providing a facile and straight forward access to tetracyclic dihydroindeno[1,2,3‐de]chromene bearing a chiral fluorene skeleton. A good functional group tolerance, high stereoselectivity, as well as the good chiroptical properties (high fluorescence quantum yields, circular dichroism) of the products make this approach highly attractive. Moreover, density functional theory (DFT) calculations indicate that the protonation of five‐membered palladacycle intermediate is more favorable rather than its direct reductive elimination process. [ABSTRACT FROM AUTHOR]

Vinylaziridines are important building blocks in organic chemistry, especially in the synthesis of nitrogen‐containing heterocycles. The direct and efficient transfer of an appropriate nitrogen source to readily accessible conjugated dienes is a notable methodology. The Pd‐catalyzed oxidative 1,2‐difunctionalization of conjugated dienes through a π‐allyl‐palladium species should be an ideal method for the selective synthesis of vinylaziridines. However, this method faces the challenge of regioselectivity, often resulting in 1,4‐difunctionalization instead. In this study, we developed a Pd‐catalyzed aerobic 1,2‐difunctionalization of conjugated dienes via a π‐allyl‐palladium species to achieve regio‐, site‐ and stereo‐selective aziridination under the synergistic effects of PdII, CuI, I−, and O2. The π‐allyl palladium species formed in the system undergoes an unusual iodination process, leading to the formation of an allyl iodide intermediate. Subsequently, the vinylaziridine is obtained through intramolecular SN2′ substitution of the allyl iodide. [ABSTRACT FROM AUTHOR]

Lithium, sodium, and potassium derivatives of amino‐acid derived bis(dithiocarbamate) complexes of bivalent nickel, palladium, platinum, and copper are readily available by treatment of the carboxylic‐acid functionalized complexes with the respective alkali metal hydroxide. Representative derivatives of the types A4[M(L1)2], A2[M(HL1)2], A[M(HL1)(H2L1)] (N‐dithioato‐iminodiacetate, L1), and A2[M(L2,3)2] (N‐dithioato‐l‐prolinate, L2, and ‐N‐benzylglycinate, L3; A=Li, Na, K; M=Ni, Pd, Pt, Cu) were isolated and characterized by spectroscopic and thermal methods. Six entries were accessible to single‐crystal X‐ray structure determination, revealing the presence of different coordination‐polymeric structures and hydrogen‐bonded assemblies comprising solvent‐separated cations in the solid state. While the transition metal always retains its all‐sulfur coordination with defined geometry, the alkali metals are structurally more flexible. The latter are usually coordinated by carboxylate and water, but additional interactions with sulfur donors are also relevant in some cases. [ABSTRACT FROM AUTHOR]

A strategy to access fluorinated spiroindolenines has been developed, involving a selective functionalization of indoles with fluorinated moieties and subsequent catalytic dearomatization. Trifluomethylthio (SCF3), diethyl phosphono(difluoromethyl)thio (SCF2P(O)(OEt)2) and (phenylsulfonyl)difluoromethyl (CF2SO2Ph) groups were embedded at the C2 position of indole derivatives substituted with alkynes, allenes, and allyl carbonate moieties at the C3 position. A gold‐catalyzed cycloisomerization gave access to five spiroindolenines, and an enantioselective palladium catalyzed cyclization provided 10 fluorinated spirocyclic products with up to 77% ee. [ABSTRACT FROM AUTHOR]

Air‐stable cyclometalated palladium(II) complexes with benzamide ligands were synthesized in high yields and characterized by X‐ray diffraction analysis, CVA, 1H NMR, 13C NMR spectroscopy, MALDI‐MS, and ESI‐MS. The electrochemical oxidation of the complexes is reversible in the presence of a quinoline substituent in the ligand and gives Pd (III) species that do not undergo reductive elimination and are detectable by ESR spectroscopy. The complexes showed high cytotoxicity against cervical cancer (M‐HeLa) and duodenal adenocarcinoma (HuTu 80), a human mammary ductal adenocarcinoma line (MCF‐7) and a human lung carcinoma cell line (A549). The possibility of generating reactive oxygen species in solution (such as OH−radicals), which can be responsible for the antitumor activity of the studied complexes, using the ESR method was shown. [ABSTRACT FROM AUTHOR]

A fundamental understanding of the active sites in working catalysts can guide the rational design of new catalysts with improved performances. In this work, we have followed the evolution of homogeneous and heterogeneous Pd catalysts under the reaction conditions for aerobic oxidative coupling of toluene for the production of 4,4′-bitolyl. We have found that subnanometer Pd clusters made with a few Pd atoms are the working active sites in both homogeneous and heterogeneous catalytic systems. Moreover, water can promote the activity of Pd clusters by nearly one-order magnitude for oxidative coupling reaction by facilitating the activation of O2. These new insights lead to the preparation of a catalyst made with Pd clusters supported on a two-dimensional zeolite, which expands the scope of the oxidative coupling of aromatics to larger substrates. A fundamental understanding of the active sites in working catalysts can guide the rational design of new catalysts with improved performances. Here, regioselective oxidative coupling of toluene to 4,4'-bitolyl is achieved with zeolite-encapsulated Pd catalysts under acid-free conditions, and the active sites are identified to be the subnanometer Pd clusters confined in the channels of Beta zeolite. [ABSTRACT FROM AUTHOR]

AbstractResins impregnated with organic extractants regarded as effective adsorbent materials due to their ability for selective sorption. These resins consist of a polymeric material that is infused with accessible organic extractants. Furthermore, these resins merge the unique properties and the distinctive characteristics of both liquid-liquid extraction and solid-liquid sorption processes. In this work, the impregnation of Styrene divinyl benzene beads (SM-2 beads) with triisobutylphosphine sulfide (TIBPS = CYANEX 471X) was prepared. A SM-2 bead functionalized with CYANEX 471X (SM-2-TIBPS beads) was characterized using scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FT-IR) techniques and investigated for recovery and separation of palladium ions from a 3 M nitric acid solution. Various parameters were studied, as shaking time effect, nitric acid concentration, SM-2-TIBPS beads weight, Pd(II) concentration and temperature. The Pd(II)/SM-2-TIBPS sorption system has an endothermic nature and was fitted with a Langmuir isotherm model with a 0.9860 regression factor. The kinetics modeling was fitted with PSO and IPD models with regression factors of 0.9889 and 0.9959, respectively. The maximum monolayer sorption capacity of SM-2-TIBPS was found to be 17.47 ± 0.9 mg/g. The sorption of Pd(II) from different media at 3 M takes the following sequence: HNO3 > HCl > H2SO4. Desorption of about 76.38 ± 2.4% was achieved with (1 M + 1 M) of thiourea + HCl after one desorption stage. Effect of other interfering ions, as Pt(II), Pb(II), Eu(III), Cu(II), Mo(VI), Co(III), Zr(IV), Fe(III), Cd(II), and Ce(III), indicates high separation factors between Pd(II) and other investigated metal ions, which ranged from 9.4 to 35. [ABSTRACT FROM AUTHOR]

An efficient approach for the synthesis of substituted aryl naphthoquinones via a Pd(II)‐catalyzed template‐assisted m−C(sp2)−H bond functionalization reaction of arylmethane sulfonates have been demonstrated. The method involves usage of less expensive and abundant pharmacologically important scaffold naphthoquinone. A wide range of arylmethane sulfonates were examined and found to be compatible with the protocol. The protocol has also been further extended to the synthesis of various substituted aryl maleimide scaffolds. A plausible reaction mechanism has also been proposed to account for the selective distal m−C(sp2)−H bond functionalization reaction. [ABSTRACT FROM AUTHOR]

Defect engineering is a key chemical tool to modulate the electronic structure and reactivity of nanostructured catalysts. Here, it is reported how targeted introduction of defect sites in a 2D palladium metallene nanostructure results in a highly active catalyst for the alkaline oxygen reduction reaction (ORR). A defect‐rich WOx and MoOx modified Pd metallene (denoted: D‐Pd M) is synthesized by a facile and scalable approach. Detailed structural analyses reveal the presence of three distinct atomic‐level defects, that are pores, concave surfaces, and surface‐anchored individual WOx and MoOx sites. Mechanistic studies reveal that these defects result in excellent catalytic ORR activity (half‐wave potential 0.93 V vs. RHE, mass activity 1.3 A mgPd−1 at 0.9 V vs. RHE), outperforming the commercial references Pt/C and Pd/C by factors of ≈7 and ≈4, respectively. The practical usage of the compound is demonstrated by integration into a custom‐built Zn‐air battery. At low D‐Pd M loading (26 µgPd cm−2), the system achieves high specific capacity (809 mAh gZn−1) and shows excellent discharge potential stability. This study therefore provides a blueprint for the molecular design of defect sites in 2D metallene nanostructures for advanced energy technology applications. [ABSTRACT FROM AUTHOR]

Pd‐catalysis has stood as a pivotal force in synthetic transformations for decades, maintaining its status as a paramount tool in the realm of C−H bond activation. While functionalization at proximal positions has become commonplace, achieving selective and sustainable access to distal positions continues to captivate scientific endeavors. Recently, a noteworthy trend has emerged, focusing on the utilization of non‐covalent interactions to address the challenges associated with remote functionalization. The integration of these non‐covalent interactions into palladium catalysis stands as a justified response to the demands of achieving selective transformations at distal positions. This review delves into the latest advancements and trends surrounding the incorporation of non‐covalent interactions within the field of palladium catalysis. Furthermore, it is noteworthy to emphasize that multifunctional templates, particularly those harnessing hydrogen bonding, present an elegant and sophisticated approach to activate C−H bonds in a highly directed fashion. These templates showcase versatility and demonstrate potential applications across diverse contexts within the area of remote functionalization. [ABSTRACT FROM AUTHOR]

Ethylene dimerization is an industrial process that is currently carried out using homogeneous catalysts. Here we present a highly active heterogeneous catalyst containing minute amounts of atomically dispersed Pd. It requires no co‐catalyst(s) or activator(s) and significantly outperforms previously reported catalysts tested under similar reaction conditions. The selectivity to C4‐ and C6‐hydrocarbons was about 80 % and 10 % at 42 % ethylene conversion at 200 °C using an industrially relevant feed containing 50 vol % ethylene, respectively. Our kinetic and catalyst characterization experiments complemented by density functional theory calculations provide molecular insights into the local environment of isolated Pd(II)Ox species and their role in achieving high activity in the target reaction. When the developed catalyst was rationally integrated with a Mo‐containing olefin metathesis catalyst in the same reactor, the formed butenes reacted with ethylene to propylene with a selectivity of 98 % at about 24 % ethylene conversion. [ABSTRACT FROM AUTHOR]

The electrooxidation of catalyst surfaces is across various electrocatalytic reactions, directly impacting their activity, stability and selectivity. Precisely characterizing the electrooxidation on well‐defined surfaces is essential to understanding electrocatalytic reactions comprehensively. Herein, we employed in situ Raman spectroscopy to monitor the electrooxidation process of palladium single crystal. Our findings reveal that the Pd surface's initial electrooxidation process involves forming *OH intermediate and ClO4− ions facilitate the deprotonation process, leading to the formation of PdOx. Subsequently, under deep electrooxidation potential range, the oxygen atoms within PdOx contribute to creating surface‐bound peroxide species, ultimately resulting in oxygen generation. The adsorption strength of *OH and the coverage of ClO4− can be adjusted by the controllable electronic effect, resulting in different oxidation rates. This study offers valuable insights into elucidating the electrooxidation mechanisms underlying a range of electrocatalytic reactions, thereby contributing to the rational design of catalysts. [ABSTRACT FROM AUTHOR]

The transition metal‐catalyzed asymmetric hydro‐functionalization of 1,3‐dienes has been well explored, but most reactions focus on electron‐neutral substrates in an intermolecular manner. Here we first demonstrate that readily available 2,4‐dienyl hydrazones and oximes can be efficiently utilized in the hydro‐cyclization reaction under co‐catalysis of a Brønsted acid and a chiral palladium complex, furnishing multifunctional dihydropyrazones and dihydroisoxazoles, respectively. Diverse substitution patterns for both types of electron‐deficient diene compounds are tolerated, and corresponding heterocycles were generally constructed with moderate to excellent enantioselectivity, which can be elaborated to access products with higher molecular complexity and diversity. Control experiments and density functional theory calculations support that α‐regioselective protonation of dienyl substrates by acid and concurrent π‐Lewis base activation of Pd0 complex is energetically favoured in the formation of active π‐allylpalladium intermediates, and an outer‐sphere allylic amination or etherification mode is adopted to deliver the observed cyclized products enantioselectively. [ABSTRACT FROM AUTHOR]

Palladium‐catalyzed carbonylation of allyl alcohol to 3‐butenoic acid has been investigated. A significant effect of halide promoters, p‐tolylsulfonic acid (TsOH), water, solvents, and PPh3 concentration activity and selectivity has been studied. Detailed kinetics of this reaction was investigated in a temperature range of 363–383 K. The influence of parameters such as stirring speed, allyl alcohol, catalyst, benzyltriethylammonium chloride (BTEAC), TsOH concentrations, and CO partial pressures on the activity and selectivity has been studied. An empirical rate equation was suggested and found to be fairly consistent with observed rate data. In addition, the activation energy and kinetic parameters were evaluated. [ABSTRACT FROM AUTHOR]

Die Ethylen‐Dimerisierung ist ein industrieller Prozess, der derzeit mit homogenen Katalysatoren durchgeführt wird. Hier stellen wir einen hochaktiven heterogenen Katalysator vor, der winzige Mengen von atomar dispergiertem Pd enthält. Er erfordert keine Cokatalysatoren oder Aktivatoren und übertrifft die Leistung früherer Katalysatoren, die unter ähnlichen Reaktionsbedingungen getestet wurden. Die Selektivität für C4‐ und C6‐Kohlenwasserstoffe betrug bei 200 °C etwa 80 % bzw. 10 % bei 42 % C2H4‐Umsatz unter Verwendung eines industriell relevanten Reaktionsgemisches mit 50 Vol.‐% Ethylen. Unsere Experimente zur Kinetik und Katalysatorcharakterisierung, ergänzt durch Dichtefunktionaltheorie‐Berechnungen, liefern molekulare Einblicke in die lokale Umgebung isolierter Pd(II)Ox‐Spezies und ihre Rolle bei der Erzielung einer hohen Aktivität in der Zielreaktion. Als der entwickelte Katalysator rationell mit einem Mo‐haltigen Olefinmetathesekatalysator im gleichen Reaktor integriert wurde, reagierten die gebildeten Butene mit Ethylen zu Propylen mit einer Selektivität von 98 % bei etwa 24 % C2H4‐Umsatz. [ABSTRACT FROM AUTHOR]

The present article presents a personal account on the synthesis of heterocycles by the combination of regioselective Pd-catalyzed cross-coupling reactions of polyhalogenated heterocycles, i.e., Suzuki–Miyaura and Sonogashira reactions, with alkyne-carbonyl-metathesis (ACM) reactions. The products, which show interesting optical, electronic or medicinal properties, are not readily available by other methods. [ABSTRACT FROM AUTHOR]

Metal migration strategy can offer BH functionalization of o‐carboranes at different positions from where initial bond activation occurs to achieve bifunctionalized o‐carboranes in one reaction. We report in this article an enantioselective 3,4‐bifunctionalization of o‐carboranes via asymmetric Pd migration with a high efficiency and up to 98 % ee. This asymmetric catalysis has a broad substrates scope, leading to the preparation of a class of chiral‐at‐cage o‐carborane derivatives. The enantiocontrol model is suggested on the basis of density functional theory (DFT) results, where the chiral Trost ligand plays a crucial role in this enantioselective Pd migration from exo‐alkenyl sp2 C to the cage B(4) position of o‐carborane. [ABSTRACT FROM AUTHOR]

Carbazole derivatives are vital in medicinal and materials chemistry, yet accessing diverse substitutions remains challenging. Here, we introduce a regioselective approach for C1 and C8 alkynylation of carbazoles via palladium‐catalyzed C−H activation. This method provides a direct route to mono‐ and di‐alkynylated derivatives, addressing the scarcity of alkynylated carbazole‐based materials. Our study broadens the synthetic toolbox for carbazole functionalization, offering potential applications in optoelectronics, bio‐imaging, and beyond, while contributing to developing sustainable C−H activation methodologies. [ABSTRACT FROM AUTHOR]

An N‐heterocyclic carbene palladium (NHC‐palladium)‐catalyzed denitrogenative coupling of aryldiazonium salts with terminal alkynes in ionic liquids has been accomplished. This catalytic strategy provides an effective and green synthetic protocol for the assembly of structurally diverse internal alkynes with excellent functional group compatibility and mild conditions. In the presence of 1 mol % of IMes‐Pd‐Im‐Cl2 as the catalyst, a wide range of terminal alkynes and aryldiazonium salts could be excellently tolerated. Basic ionic liquid plays a crucial role in this catalytic system, which not only acts as the green solvent, but also provides basic environment for the carbon‐carbon bond formation process. Notably, this catalytic system could be recycled up to six times and reused without significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]

Furfural is an attractive bio‐based platform chemical that has many derivatives of commercial interest. Herein, we show that the selectivity of the direct furfural reduction can be steered from 2‐methylfuran and 2‐methyltetrahydrofuran to furfuryl alcohol and tetrahydrofurfuryl alcohol by varying the ratio of formic acid and sodium formate. These reagents take the role of terminal reductants in the disclosed heterogeneous Pd‐catalysed process. We report the development and optimisation of the reaction conditions for three different products directly from furfural: 2‐methyltetrahydrofuran, tetrahydrofurfuryl alcohol and 2‐methylfuran which were obtained in 59 %, 46 %, and 63 % selectivity, respectively. Furthermore, the protocol uses commercially available Pd/Al2O3 as catalyst and the formic acid and sodium formate can be obtained from biogenous sources. [ABSTRACT FROM AUTHOR]

ABSTRACT Ionic liquids (ILs) have been recognized for their potential as environmentally friendly solvents when compared to traditional organic solvents. Additionally, their function goes beyond that of solvents, and cocatalysts, as they frequently act as stabilizing agents and ligands for the metal‐active species and intermediates in catalytic systems. This comprehensive review primarily focuses on the application of Pd‐incorporated ILs in catalyzing cross‐coupling Suzuki reactions. The responses play a vital role in creating a wide range of structurally diverse and highly functionalized organic compounds, focusing specifically on nucleopalladation Suzuki coupling reactions. The review provides a detailed summary of the reaction conditions, stereoselectivity and regioselectivity, and the underlying mechanisms. Furthermore, it underscores crucial and characteristic illustrations, displaying the practical implementations of these coupling reactions. The aim of this review is to stimulate further research efforts, with the ultimate goal of expanding our understanding and utilization of ILs in various fields in the future. [ABSTRACT FROM AUTHOR]

A Pd‐catalyzed asymmetric isomerization‐hydroamidocarbonylation of amide‐containing alkenes was developed, affording a variety of chiral α‐alkyl succinimides in moderate to good yields with high enantioselectivities. The key to success was introducing bulky 1‐adamentyl P‐substitution and 2,3,5,6‐tetramethoxyphenyl group into the rigid P‐chirogenic bisphosphine ligand to create stronger steric hinderance and deeper catalytic pocket. By this approach, regio‐ or stereo‐convergent synthesis of enantiomeric succinimides from the mixture of olefin isomers was achieved. [ABSTRACT FROM AUTHOR]