Anionic Ligands Research Articles

Regiodivergent and Enantioselective Synthesis of Cyclic Sulfones via Ligand-Controlled Nickel-Catalyzed Hydroalkylation.

Cyclic sulfones have demonstrated important applications in drug discovery. However, the catalytic and enantioselective synthesis of chiral cyclic sulfones remains challenging. Herein, we develop nickel-catalyzed regiodivergent and enantioselective hydroalkylation of sulfolenes to streamline the synthesis of chiral alkyl cyclic sulfones. The method has broad scope and high functional group tolerance. The regioselectivity can be controlled by ligands only. A neutral PYROX ligand favors C3-alkylation whereas an anionic BOX ligand favors C2-alkylation. This control is kinetic in origin as the C2-bound Ni intermediates are always thermodynamically more stable. Reactivity study of a wide range of relevant Ni intermediates reveal a NiI/NiIII catalytic cycle with a NiII-H species as the resting state. The regio- and enantio-determining step is the insertion of this NiII-H species into 2-sulfolene. This work provides an efficient catalytic method for the synthesis of an important class of organic compounds and enhances the mechanistic understanding of Ni-catalyzed stereoselective hydroalkylation.

Regiodivergent and Enantioselective Synthesis of Cyclic Sulfones via Ligand‐Controlled Nickel‐Catalyzed Hydroalkylation

Cyclic sulfones have demonstrated important applications in drug discovery. However, the catalytic and enantioselective synthesis of chiral cyclic sulfones remains challenging. Herein, we develop nickel‐catalyzed regiodivergent and enantioselective hydroalkylation of sulfolenes to streamline the synthesis of chiral alkyl cyclic sulfones. The method has broad scope and high functional group tolerance. The regioselectivity can be controlled by ligands only. A neutral PYROX ligand favors C3‐alkylation whereas an anionic BOX ligand favors C2‐alkylation. This control is kinetic in origin as the C2‐bound Ni intermediates are always thermodynamically more stable. Reactivity study of a wide range of relevant Ni intermediates reveal a NiI/NiIII catalytic cycle with a NiII‐H species as the resting state. The regio‐ and enantio‐determining step is the insertion of this NiII‐H species into 2‐sulfolene. This work provides an efficient catalytic method for the synthesis of an important class of organic compounds and enhances the mechanistic understanding of Ni‐catalyzed stereoselective hydroalkylation.

Surface complexation adsorption of Tl(III) by Fe and Mn (hydr)oxides

Thallium(III) (Tl(III)) is mobile in acidic environments and under ligand complexation, posing a potential threat to the environment and human health. The adsorption of Tl(III) on manganese and iron (hydr)oxides will affect its environmental mobility and engineering removal efficiency. However, the adsorption behavior and interfacial reaction mechanism of Tl(III) remain largely unknown. This study is the first to elucidate the surface complexation mechanism of Tl(III) on Fe/Mn (hydr)oxides and to investigate the adsorption behavior of Tl(III) under the influence of typical environmental ligands. Deprotonation of surface hydroxyl groups contributes to the increase in adsorption capacity for Tl(III) (δ-MnO2, 1619.93 mg g−1; α-FeOOH, 48.25 mg g−1; and α-Fe2O3, 58.66 mg g−1 from Langmuir thermodynamic fitting). Surface complexation modeling reveals tridentate complexation of Tl(III) on birnessite and monodentate complexation on iron (hydr)oxides. The anionic ligand strongly inhibits the adsorption of Tl(III) (up to 16.0 %–40.0 %) by complexing with Tl(III) and occupying the adsorption sites. In addition, HA also reduces the adsorption of Tl(III) by 8.2 %–23.2 % by exacerbating the aggregation and surface coating of the adsorbent particles. New insights into the binding mechanism of Tl(III) on Fe/Mn oxides can help to guide the development of efficient Tl(III) removal adsorbents.

Metal saccharinate complexes with N,N-bis(2-hydroxyethyl)ethylendiamine: Synthesis, structural, thermal decomposition and DFT studies

New Co(III), Ni(II), Cu(II), and Zn(II) saccharinate (Sac) complexes bearing with N,N-bis(2-hydroxyethyl)ethylenediamine (N-bishydeten), namely [Co(2HN-bishydeten)2](Sac)⋅2H2O, [Ni(Sac)2(N-bishydeten)], [Cu(N-bishydeten)2](Sac)2 and [Zn(Sac)2(N-bishydeten)] were synthesized and characterized using UV–Vis, IR spectroscopy and magnetic susceptibility measurements. The crystal structures of the complexes were analysed by single crystal X-ray diffraction. Both N-bishydeten and Sac displayed coordination versality. The N-bishydeten ligands were octahedrally coordinated as two tridentate anionic ligands (2HN-bishydeten) (N, N, O-) to the Co(III) and two tridentate neutral ligands (N, N, O) to the Cu(II). The anionic Sac ligand was also located outside the coordination sphere in these complexes. However, the N-bishydeten ligand behaved as a tetradentate ligand (O, N, O, N) in the Ni(II) and Zn(II) complexes while two Sac ligands were coordinated the corresponding metals ions in a monodentate fashion, one through the N atom and the other via the carbonyl O atom. Thermal decomposition of the complexes was studied in inert atmosphere and thermal analysis data (TG and DTA) indicated multi-step decompositions of the metal complexes decomposed in a single stage. The thermal decomposition products were estimated as metal oxides. Finally, the structural properties of all complexes were investigated through quantum chemical computations.

Precise Post‐Synthetic Modification of Heterometal‐Organic Capsules for Selectively Encapsulating Tetrahedral Anions

AbstractPost‐synthetic modification plays a crucial role in precisely adjusting the structure and functions of advanced materials. Herein, we report the self‐assembly of a tubular heterometallic Pd3Cu6L16 capsule that incorporates Pd(II) and CuL1 metalloligands. This capsule undergoes further modification with two tridentate anionic ligands (L2) to afford a bicapped Pd3Cu6L16L22 capsule with an Edshammer polyhedral structure. By employing transition metal ions, acid, and oxidation agents, the bicapped capsule can be converted into an uncapped one. This uncapped form can then revert back to the bicapped structure on the addition of Br− ions and a base. Interestingly, introducing Ag+ ions leads to the removal of one L2 ligand from the bicapped capsule, yielding a mono‐capped Pd3Cu6L16L2 structure. Furthermore, the size of the anions critically influences the precise control over the post‐synthetic modifications of the capsules. It was demonstrated that these capsules selectively encapsulate tetrahedral anions, offering a novel approach for the design of intelligent molecular delivery systems.

Dextran sulfate bulk and surface-modified microfiltration membrane for simultaneous blood plasma harvesting and low-density lipoprotein removal during plasmapheresis

Plasmapheresis is currently used for the harvesting of blood plasma in medical labs and plasma donation centers. This is a fast, single-step membrane process for both collection of blood plasma and simultaneous blood cell isolation. This paper presents the development of a novel membrane that can be used to simultaneously harvest blood plasma and isolate low-density lipoprotein (LDL), known as bad cholesterol, from the blood. To achieve this goal, dual surface and bulk modification by dextran sulfate (DS) was performed on a polyethersulfone (PES) membrane containing single wall carbon nanotubes (SWCNT). DS is an anionic ligand that repels negatively charged substances like red blood cells (RBCs) and adsorbs positively charged substances like Apo B100; the apoprotein of LDL. Scanning Electron Microscope (SEM), Energy Dispersive X-Ray (EDX), and Fourier Transform Infrared (FTIR) spectroscopy analyses provided evidence of the grafting of DS on single wall carbon nanotubes (DS-SWCNT). Surface studies including water contact angle, zeta potential analysis, surface morphology, Attenuated Total Reflectance-FTIR (ATR-FTIR), and EDX, confirmed the presence of DS on the PES membrane surface. The SEM cross-section results showed the formation of a two-zone morphology with an open structure on the upside and a dense structure on the downside that provide optimal conditions for efficient separation of blood cells. The complete blood count (CBC) and biochemistry analyses revealed dual bulk and surface-modified membrane, and a specific sample (DM2) showed the best performance for blood cells and LDL separation. The maximum separation of blood cells was 87% RBC, 98% white blood cells (WBCs), and 83% platelets (PLTs). Moreover, DM2 exhibited a sieving ratio for LDL of 0.33. Blood compatibility analyses confirmed that DM2 and other related samples had low hemolysis and prolonged coagulation times.

Insights into the G-quadruplex DNA interaction landscape: Comparative analysis of anionic Zn(II) and Co(II) phthalocyanine-tetrasulfonate complexes.

G-quadruplexes play a pivotal role in regulating various cellular processes, including gene expression and replication, making them essential structures in understanding, and manipulating cellular functions. The development of G-quadruplex ligands holds significant promise in therapeutic and research applications, offering targeted tools to modulate G-quadruplex structures and potentially influence critical biological pathways. An exciting frontier in G-quadruplex research lies in the exploration of anionic ligands, and their profound impact on stabilizing and modulating G-quadruplex DNA. In this study, the interaction of two anionic phthalocyanine compounds (Zinc (II) phthalocyanine 3,4',4″,4‴-tetrasulfonic acid, tetrasodium salt, ZnAPC; cobalt (II) phthalocyanine 3,4',4″,4‴-tetrasulfonic acid, tetrasodium salt, CoAPC) and three separate G-quadruplex-forming DNA sequences was investigated. Interactions were carried out by DNA polymerase stop studies along with spectroscopic studies. According to the results of experimental data, it was determined that ZnAPC actively interacts with the G-quadruplex DNA structures. On the other hand, it was thought that the interaction with CoAPC was less and even occurred in simple electrostatic interactions. KD constants and Bmax constants for the interaction with ZnAPC were calculated. The KD constants for ZnAPC were found to be (1.16 ± 0.07) × 10-5 , (9.75 ± .24) × 10-6 and (1.00 ± 0.36) × 10-4 M for AS1411, Vegf, and Tel21, respectively. Accordingly, it was concluded that ZnAPC interacts with G-quadruplex DNA ligands effectively.

Sulfate ion induced formation of unsaturated coordination of AlF3 nanocluster catalyst confined in carbon framework for catalytic dehydrofluorination

The gas-phase catalytic dehydrofluorination of hydrofluorocarbons (HFCs) to produce hydrofluoroolefins is an important strategy for the resource utilization of HFCs. AlF3 is the most suitable and efficient catalyst for dehydrofluorination of HFCs. However, sintering and preservation of coordinatively unsaturated aluminum centers pose significant challenges for AlF3 catalysts. Herein, we prepared carbon-confined AlF3 nanocluster catalysts with aluminum fumarate metal organic frameworks (AlFu-MOF) as the precursors, followed by carbonization and fluorination treatments. During catalyst preparation, anion ligand in the aluminum salt plays a major role in the formation of coordinatively unsaturated Al centers. Compared with Al(NO3)3·9H2O and AlCl3·6H2O, AlFu-MOF (named AlFu-S) prepared with Al2(SO4)3·18H2O exhibits a higher concentration of Al-OH species. Additionally, the residual SO42- ions can indeed retard the crystallization of AlF3 at elevated temperatures. Hence, the decomposition of Al-OH groups and the presence of residual SO42- ions in AlFu-S contribute together to the abundance of unsaturated coordinated Al centers in the finally carbon-confined AlF3 nanocluster catalyst (named AlFu-S-550-F). Also, the confinement effect of the carbon material formed by the carbonization of AlFu-S effectively prevent AlF3 nanocluster from sintering and phase transition, hence, in the dehydrofluorination of HFC-134a, AlFu-S-550-F demonstrates excellent stability compared to AlF3 catalysts prepared by precipitation methods. In summary, this study provides a strategy for the preservation of coordinatively unsaturated aluminum centers in AlF3 catalysts due to sintering and crystal structure transformation. Furthermore, the methodology proposed in this work is also applicable to the preparation of other coordinatively unsaturated metal catalysts.

A Route to Two-Dimensional Room-Temperature Organometallic Multiferroics: The Marriage of d-p Spin Coupling and Structural Inversion Symmetry Breaking.

Two-dimensional (2D) room-temperature multiferroic materials are highly desirable but still very limited. Herein, we propose a potential strategy to obtain such materials in 2D metal-organic frameworks (MOFs) by utilizing the d-p direct spin coupling in conjunction with center-symmetry-breaking six-membered heterocyclic rings. Based on this strategy, a screening of 128 2D MOFs results in the identification of three multiferroics, that is, Cr(1,2-oxazine)2, Cr(1,2,4-triazine)2, and Cr(1,2,3,4-trazine)2, simultaneously exhibiting room-temperature ferrimagnetism and ferroelectricity/antiferroelectricity. The room-temperature ferrimagnetic order (306-495 K) in these MOFs originates from the strong d-p direct magnetic exchange interaction between Cr cations and ligand anions. Specifically, Cr(1,2-oxazine)2 exhibits ferroelectric behavior with an out-of-plane polarization of 4.24 pC/m, whereas the other two manifest antiferroelectric characteristics. Notably, all three materials present suitable polarization switching barriers (0.18-0.31 eV). Furthermore, these MOFs are all bipolar magnetic semiconductors with moderate band gaps, in which the spin direction of carriers can be manipulated by electrical gating.

Coordination Modes and Binding Patterns in Lanthanum Phosphoramide Complexes.

A monoanionic phosphoramide ligand is introduced, which forms a series of lanthanum complexes with the ligand in both anionic and neutral forms. Stoichiometric control alone provides monometallic complexes with either two or three phosphoramide ligands. Alternatively, a combination of anionic and neutral proteo ligands featuring intramolecular hydrogen bonding can be obtained. The anionic form of the ligand binds lanthanum as a bi- or monodentate ligand, depending on the steric demand at the metal center, while the protonated ligand binds exclusively through the phosphoramide oxygen donor.

(Electro)chemical N2 Splitting by a Molybdenum Complex with an Anionic PNP Pincer-Type Ligand

(Electro)chemical N₂ Splitting by a Molybdenum Complex with an Anionic PNP Pincer-Type Ligand

Lemieux‐Johnson oxidation with N,N‐bidentate bisPYA ruthenium complexes: insights into reaction conditions and catalyst design

AbstractThe carbonyl group is arguably the most versatile functional group for synthetic purposes. Here, a series of N,N’‐bis(pyridylideneamide) (bisPYA) complexes of ruthenium(II), [Ru(cym)(bisPYA)Cl]+ (cym=cymene), were synthesized and applied as catalysts for Lemieux‐Johnson oxidation of alkenes to access carbonyl functionalities. Complexes bearing para‐ and ortho‐bisPYA ligands induce higher activity and selectivity than their mesoionic meta‐bisPYA analogues. The non‐coordinating counterion of the cationic complexes affects the catalytic performance markedly, with PF6− enhancing the activity compared to trifluoromethanesulfonate, OTf−. Likewise, replacing the anionic ancillary chloride ligand by a neutral and more labile MeCN ligand led to increased activity. Electrochemical and solubility measurements revealed no direct correlation of ligand donor strength to catalytic performance. Variation of the solvent mixture and the ratio of its components provided access to high‐performance catalysts. In H2O/MeCN/CH2Cl2 at 3 : 1:0.5 (v/v) ratio, turnover frequencies up to 10,000 h−1 were obtained for the Lemieux‐Johnson oxidation of styrene with these Ru(bisPYA) complexes, allowing quantitative conversions within 30 min at 0.1 mol % catalyst loadings and corresponding to a 5 times faster reaction than the best catalyst known to date for this transformation.

Precise Post-Synthetic Modification of Heterometal-Organic Capsules for Selectively Encapsulating Tetrahedral Anions.

Post-synthetic modification plays a crucial role in precisely adjusting the structure and functions of advanced materials. Herein, we report the self-assembly of a tubular heterometallic Pd3 Cu6 L16 capsule that incorporates Pd(II) and CuL1 metalloligands. This capsule undergoes further modification with two tridentate anionic ligands (L2) to afford a bicapped Pd3 Cu6 L16 L22 capsule with an Edshammer polyhedral structure. By employing transition metal ions, acid, and oxidation agents, the bicapped capsule can be converted into an uncapped one. This uncapped form can then revert back to the bicapped structure on the addition of Br- ions and a base. Interestingly, introducing Ag+ ions leads to the removal of one L2 ligand from the bicapped capsule, yielding a mono-capped Pd3 Cu6 L16 L2 structure. Furthermore, the size of the anions critically influences the precise control over the post-synthetic modifications of the capsules. It was demonstrated that these capsules selectively encapsulate tetrahedral anions, offering a novel approach for the design of intelligent molecular delivery systems.

The geochemical evolution of basalt Enhanced Rock Weathering systems quantified from a natural analogue

Substantial quantities of fine-grained basaltic dust have fallen on South Iceland soils over at least the past 3300 years, making this region an ideal natural analogue to define the long-term consequences of current Enhanced Rock Weathering efforts. A relatively pristine South Iceland Gleyic/Histic Andosol, 3 m in height, receiving approximately 1250 mm of rainfall annually was selected for this study. This soil receives an estimated 500–800 g m−2y−1 of basaltic dust. The soil waters in this system were regularly sampled as a function of depth from May to November 2018. The fluid pH, alkalinity and the concentrations of most major elements increased with depth as the fluids became more reduced. In contrast, whereas numerous toxic trace metals are initially released to the fluid by the dissolution of the basalt near the surface they are scavenged at depth likely due to their uptake by secondary minerals. Equilibrium reaction path modelling suggests that 1) the added airborne basaltic dust dissolves throughout the soil column and 2) in total 0.26 cm3 of basalt dust dissolves per kg water in this soil–water system. Mass balance calculations indicate that the annual mass of basalt dissolved is less than 60 % of that added to the system, such that the mass of basaltic material in the soil column likely increases continuously over time. Basalt dissolution is maintained throughout the soil by the precipitation of Al-Si-minerals such as allophane, and organic anion ligands released from organic decay. These processes limit aqueous Al3+ activity and keep the soil waters undersaturated with respect to primary basaltic minerals and glass. The soil water pH is ∼6 and has a higher alkalinity than that of both Icelandic surface waters and the ocean. In contrast, if no basalt was present, the pH of the soil solutions would be 4.4, with zero alkalinity, illustrating the role of added basalt in drawing CO2 out of the atmosphere.

Metal–N4 model single‐atom catalyst with electroneutral quadri‐pyridine macrocyclic ligand for CO2 electroreduction

AbstractMetal–N–C single‐atom catalysts, mostly prepared from pyrolysis of metal‐organic precursors, are widely used in heterogeneous electrocatalysis. Since metal sites with diverse local structures coexist in this type of material and it is challenging to characterize the local structure, a reliable structure–property relationship is difficult to establish. Conjugated macrocyclic complexes adsorbed on carbon support are well‐defined models to mimic the single‐atom catalysts. Metal–N4 site with four electroneutral pyridine‐type ligands embedded in a graphene layer is the most commonly proposed structure of the active site of single‐atom catalysts, but its molecular counterpart has not been reported. In this work, we synthesized the conjugated macrocyclic complexes with a metal center (Co, Fe, or Ni) coordinated with four electroneutral pyridinic ligands as model catalysts for CO2 electroreduction. For comparison, the complexes with anionic quadri‐pyridine macrocyclic ligand were also prepared. The Co complex with the electroneutral ligand expressed a turnover frequency of CO formation more than an order of magnitude higher than that of the Co complex with the anionic ligand. Constrained ab initio molecular dynamics simulations based on the well‐defined structures of the model catalysts indicate that the Co complex with the electroneutral ligand possesses a stronger ability to mediate electron transfer from carbon to CO2.

Magnetic field dependence of the para-ortho conversion rate of molecular hydrogen in SABRE experiments

The use of parahydrogen – the isomer of molecular hydrogen with zero nuclear spin – is important for promising and actively developing methods for spin hyperpolarization of nuclei called parahydrogen induced polarization (PHIP). However, the dissolved parahydrogen in PHIP experiments quickly loses its spin order, resulting in the formation of orthohydrogen and reduction of the overall nuclear polarization of the substrate. This process is due to the difference of chemical shifts of hydride protons, as well as spin–spin couplings between nuclei, in the intermediate catalytic complexes, and it has not been rigorously explained so far. We proposed a new experimental technique based on magnetic field cycling for measuring the rate of molecular hydrogen para–ortho conversion in solution and applied it for non-hydrogenative PHIP Signal Amplification By Reversible Exchange (SABRE) experiments. The para–ortho conversion rate was measured over a wide range of magnetic field from 0.5 mT to 9.4 T. It was found that the conversion rate strongly depends on the magnetic field in which the reaction occurs, as well as on the concentrations of reactants. The rate decreases with increasing the concentration of pyridine ligand and increases with increasing the concentration of iridium catalyst. The model, which takes into account the reversible exchange of molecular hydrogen with the catalyst, nuclear spin–spin interaction of hydride protons with nuclei of ligands within catalytic complex and nuclear Zeeman interactions, qualitatively describes the experimental data. Two types of complexes with different spin system symmetry contribute to the molecular hydrogen conversion. In asymmetric complexes possessing hydride protons with different chemical shifts due to the presence of chlorine anion ligand the para–ortho conversion rate increases with magnetic field, while for symmetric complexes this mechanism is not operable. In the magnetic field where level anti-crossing occurs the resonant feature for the rate of para–ortho conversion is found. The results of this work can be utilized for finding the optimal conditions for obtaining the maximum hyperpolarization in the experiments employing parahydrogen.

Silver(I) complexes with diorganochalcogen ligands of type (2-MeC6H4CH2)2E (E = S, Se). Synthesis, structure and antiproliferative activity

Silver(I) complexes of types [Ag(X){E(CH2C6H4Me-2)2}] [E = S, X = CF3SO3 (1), NO3 (2), ClO4 (3); E = Se, X = CF3SO3 (4), NO3 (5), ClO4 (6)] and [Ag(X){E(CH2C6H4Me-2)2}2] [X = CF3SO3, E = S (7), Se (8); X = ClO4, E = S (9), Se (10)] were prepared by reacting the diorganochalcogenides (2-MeC6H4CH2)2E [E = S (L1), Se (L2)] with the appropriate silver(I) salt in a 1:1 and a 2:1 molar ratio, respectively. The ligands and the Ag(I) complexes were characterized by multinuclear NMR spectroscopy (1H, 13C{1H}, 19F{1H}, 77Se{1H}, as appropriate), ESI+ mass spectrometry, elemental analysis and IR spectroscopy. The crystal and molecular structures of the ligand L1 and the complexes 2, 5, 7, 8 and 9 were determined by single-crystal X-ray diffraction. The molar conductivity of the reported metal complexes showed their behaviour as 1:1 electrolytes in solution, while in solid state the inorganic anionic ligand is coordinated to silver by OAg bonds. Preliminary results showed that the silver(I) complexes bearing triflato ligands have in vitro promising antiproliferative activity against the murine melanoma B16.F10 cells.

Copper Catalyzed Enantioconvergent Nucleophilic Substitutions†

Comprehensive SummaryAs a versatile earth‐abundant transition metal, Cu has long been widely applied in the C—C and C—X bond forming reactions. As for now, low‐valent Cu(I) is known to reduce the redox active electrophiles via an SET pathway to give the corresponding radical and Cu(II) species. The resulting Cu(II) species can interact with the radical via the out‐sphere pathway, affording the coupling product. Alternatively, Cu(II) can trap the radical through the inner‐sphere process to generate Cu(III) species and then realize challenging bond formations due to the facile reductive elimination of Cu(III) intermediate. Although copper catalysis has been widely applied in arylations of various nucleophiles, copper‐catalyzed enantioconvergent nucleophilic substitutions of racemic alkyl electrophiles have been less explored, likely due to the difficulties in overcoming the reduction potential of alkyl electrophiles, elimination of side reactions, and enantiomeric control. In order to overcome the high reduction potential of alkyl electrophiles, the photo‐induced strategy has been developed under mild conditions. An alternative strategy with new anionic tridentate ligands has also been reported in this regard. This review summarizes recent developments in copper‐catalyzed enantioconvergent nucleophilic substitutions of alkyl electrophiles by various nucleophiles to realize C—N, C—C, C—B, C—P and C—O bond formations and their brief mechanistic studies. Key ScientistsIn 2016, Fu and Peters et al. reported the first photo‐induced Cu‐catalyzed enantiocovergent C—N bond formations of tertiary alkyl halides with N‐hetereocycles, opening the door for the Cu‐catalyzed enantiocovergent nucleophilic substitutions. The photo‐induced strategy has been developed that greatly enhances the reducing power of Cu(I). The Cu‐catalyzed enantioconvergent cyanation (decarboxylative) and borylation were then successively presented by Liu and Ito in 2017 and 2018, respectively. Other than the photo‐induced strategy, Liu et al. in 2019 demonstrated that anionic ligands can also significantly enhance the reducing ability of Cu(I). The cinchona‐based chiral anionic tridentate ligands have been utilized for a series of Cu‐catalyzed enantiocovergent nucleophilic substitutions. Zhang et al. also developed chiral anionic tridentate ligands containing the oxazoline binding sites in 2020. In 2020, Xiao and Lu et al. reported the Cu‐catalyzed enantiocovergent deoxygenative cyanation. Later in 2022, Feng and Liu et al. developed the new guanidine hybrid ligands. This review focuses on the Cu‐catalyzed enantioconvergent nucleophilic substitutions that emerged in recent years.

Synergistically Coupling Atomic-Level Defect-Manipulation and Nanoscopic-Level Interfacial Engineering Enables Fast and Durable Sodium Storage.

Through inducing interlayer anionic ligands and functionally modifying conductive carbon-skeleton on the transition metal chalcogenides (TMCs) parent to achieve atomic-level defect-manipulation and nanoscopic-level architecture design is of great significance, which can broaden interlayer distance, optimize electronic structure, and mitigate structural deformation to endow high-efficiency battery performance of TMCs. Herein, an intriguing 3D biconcave hollow-tyre-like anode constituted by carbon-packaged defective-rich SnSSe nanosheet grafting onto Aspergillus niger spores-derived hollow-carbon (ANDC@SnSSe@C) is reported. Systematically experimental investigations and theoretical analyses forcefully demonstrate the existence of anion Se ligand and outer-carbon all-around encapsulation on the ANDC@SnSSe@C can effectively yield abundant structural defects and Na+ -reactivity sites, accelerate rapid ion migration, widen interlayer spacing, as well as relieve volume expansion, thus further resolving the critical issues throughout the charge-discharge processes. As anticipated, as-fabricated ANDC@SnSSe@C anode contributes extraordinary reversible capacity, wonderful cyclic lifespan with 83.4% capacity retention over 2000 cycles at 20.0 A g-1 , and exceptional rate capability. A series of correlated kinetic investigations and ex situ characterizations deeply reveal the underlying springheads for the ion-transport kinetics, as well as synthetically elucidate phase-transformation mechanism of the ANDC@SnSSe@C. Furthermore, the ANDC@SnSSe@C-based sodium ion full cell and hybrid capacitor offer high-capacity contribution and remarkable energy-density output, indicative of its great practicability.

Softer Is Better for Titanium: Molecular Titanium Arsenido Anions Featuring Ti≡As Bonding and a Terminal Parent Arsinidene.

We introduce the arsenido ligand onto the TiIV ion, yielding a remarkably covalent Ti≡As bond and the parent arsinidene Ti═AsH moiety. An anionic arsenido ligand is assembled via reductive decarbonylation involving the discrete TiII salt [K(cryptand)][(PN)2TiCl] (1) (cryptand = 222-Kryptofix) and Na(OCAs)(dioxane)1.5 in thf/toluene to produce the mixed alkali ate-complex [(PN)2Ti(As)]2(μ2-KNa(thf)2) (2) and the discrete salt [K(cryptand)][(PN)2Ti≡As] (3) featuring a terminal Ti≡As ligand. Protonation of 2 or 3 with various weak acids cleanly forms the parent arsinidene [(PN)2Ti═AsH] (4), which upon deprotonation with KCH2Ph in thf generates the more symmetric anionic arsenido [(PN)2Ti(As){μ2-K(thf)2}]2 (5). Experimental and computational studies suggest the pKa of 4 to be ∼23, and the bond orders in 2, 3, and 5 are all in the range of a Ti≡As triple bond, with decreasing bond order in 4.