Divergent Reactivity of a Dinuclear (NHC)Nickel(I) Catalyst versus Nickel(0) Enables Chemoselective Trifluoromethylselenolation

An Electrocatalytic Cascade Reaction for the Synthesis of Ketones Using CO2 as a CO Surrogate

The construction of carbonyl compounds via carbonylation reactions using safe CO sources remains a long-standing challenge to synthetic chemists. Herein, we propose a catalyst cascade Scheme in which CO2 is used as a CO surrogate in the carbonylation of benzyl chlorides. Our approach is based on the cooperation between two coexisting catalytic cycles: the CO2-to-CO electroreduction cycle promoted by [Fe(TPP)Cl] (TPP=meso-tetraphenylporphyrin) and an electrochemical carbonylation cycle catalyzed by [Ni(bpy)Br2] (2,2'-bipyridine). As a proof of concept, this protocol allows for the synthesis of symmetric ketones from good to excellent yields in an undivided cell with non-sacrificial electrodes. The reaction can be directly scaled up to gram-scale and operates effectively at a CO2 concentration of 10 %, demonstrating its robustness. Our mechanistic studies based on cyclic voltammetry, IR spectroelectrochemistry and Density Functional Theory calculations suggest a synergistic effect between the two catalysts. The CO produced from CO2 reduction is key in the formation of the [Ni(bpy)(CO)2], which is proposed as the catalytic intermediate responsible for the C-C bond formation in the carbonylation steps.

Oxidative Addition and β-Hydride Elimination by a Macrocyclic Dinickel Complex: Observing Bimetallic Elementary Reactions

The dinickel(I) complex Ni2 (tBu PONNOPONNO), featuring a planar macrocyclic diphosphoranide ligand tBu PONNOPONNO, offers a unique architectural platform for observing bimetallic elementary reactions. Oxidative addition reactions of alkyl halides produce dinickel(II) complexes of the type Ni2 (μ-R)(μ-X)(tBu PONNOPONNO). However, when R=Et β-hydride elimination is observed to form a dinickel monohydride, with the rate dependent on the nature of X. DFT studies suggest a new mechanism for bimetallic β-hydride elimination, where the rate dependence arises from the steric pressure imposed by the X group on the opposing trans face of the dinickel macrocycle. This work enhances understanding of bimetallic elementary reactions, particularly β-hydride elimination, which have not been well-explored for dinuclear systems.

N-Trifluoromethylselenophthalimide, an Electrophilic Trifluoromethylselenolation Reagent and Its Application for the Synthesis of 4-Trifluoromethylselenolated Isoxazoles

A new electrophilic trifluoromethylselenolation reagent, N-trifluoromethylselenophthalimide (Phth-SeCF3), was developed. A strategy for the synthesis of 4-trifluoromethylselenolated isoxazoles through electrophilic trifluoromethylselenolation cyclization has been established by using Phth-SeCF3 as an electrophilic reagent. Moreover, this protocol has the features of broad substrate scope, good functional group tolerance, and high yields.

Machine Learning-Guided Development of Trialkylphosphine Ni(I) Dimers and Applications in Site-Selective Catalysis

Owing to the unknown correlation of a metal's ligand and its resulting preferred speciation in terms of oxidation state, geometry, and nuclearity, a rational design of multinuclear catalysts remains challenging. With the goal to accelerate the identification of suitable ligands that form trialkylphosphine-derived dihalogen-bridged Ni^(I) dimers, we herein employed an assumption-based machine learning approach. The workflow offers guidance in ligand space for a desired speciation without (or only minimal) prior experimental data points. We experimentally verified the predictions and synthesized numerous novel Ni^(I) dimers as well as explored their potential in catalysis. We demonstrate C-I selective arylations of polyhalogenated arenes bearing competing C-Br and C-Cl sites in under 5 min at room temperature using 0.2 mol % of the newly developed dimer, [Ni^(I)(μ-Br)PAd₂(n-Bu)]₂, which is so far unmet with alternative dinuclear or mononuclear Ni or Pd catalysts.

Bimetallic Nickel Complexes Supported by a Planar Macrocyclic Diphosphoranide Ligand

Metal-metal cooperativity is emerging as an important strategy in catalysis. This requires appropriate ligand scaffolds that can support two metals in close proximity. Here we report nickel-promoted formation of a dinucleating planar macrocyclic ligand that can support bimetallic dinickel(II) and dinickel(I) complexes. Reaction outcomes can be tuned by variation of the substituents and reaction conditions to favour dinucleating macrocyclic, mononucleating macrocyclic or conventional pincer architectures.

Elucidating electron-transfer events in polypyridine nickel complexes for reductive coupling reactions

Polypyridine-ligated nickel complexes are widely used as privileged catalysts in a variety of cross-coupling reactions. The rapid adoption of these complexes is tentatively attributed to their ability to shuttle between different oxidation states and engage in electron-transfer reactions. However, these reactions are poorly understood in mechanistic terms. Here we investigate the reactivity of pseudohalide- and halide-ligated Ni(II) complexes, containing polypyridine ligands, in electron-transfer reactions. Specifically, Ni(II) halide complexes trigger comproportionation with Ni(0) with exceptional ease en route to Ni(I)L n species, whereas the corresponding Ni(II) pseudohalide congeners are resistant to electron transfer, with Ni(I) pseudohalides being prone to disproportionation events. These observations are corroborated by electrochemical techniques and detailed quantum mechanical calculations. We also show that catalytically inactive Ni(II) pseudohalide complexes can be reactivated in the presence of exogeneous salts. From a broader perspective, this study provides rationalizations for overlooked and fundamental steps within the Ni-catalysed cross-coupling arena, thus offering blueprints for designing future Ni-catalysed reactions.

Redox-Neutral Transformations of Carbon Dioxide Using Coordinatively Unsaturated Late Metal Silyl Amide Complexes

Two-coordinate silylamido complexes of nickel and copper rapidly react with CO₂ to selectively form a new cyanate ligand along with hexamethyldisiloxane byproducts. Mechanistic insight into these reactions was obtained from the synthesis of proposed intermediates, several silyl- and phenyl- substituted amido analogues, and their subsequent reactivity with CO₂. These studies suggest that a unique intramolecular double silyl transfer step facilitates CO₂ deoxygenation, which likely contributes to the rapid rates of reaction. The deoxygenation reactions create a platform for a synthetic cycle in which copper amido complexes convert CO₂ to organic silylcarbamates.

Structure-Reactivity Relationships of Buchwald-Type Phosphines in Nickel-Catalyzed Cross-Couplings

The dialkyl-ortho-biaryl class of phosphines, commonly known as Buchwald-type ligands, are among the most important phosphines in Pd-catalyzed cross-coupling. These ligands have also been successfully applied to several synthetically valuable Ni-catalyzed cross-coupling methodologies and, as demonstrated in this work, are top performing ligands in Ni-catalyzed Suzuki Miyaura Coupling (SMC) and C-N coupling reactions, even outperforming commonly employed bisphosphines like dppf in many circumstances. However, little is known about their structure-reactivity relationships (SRRs) with Ni, and limited examples of well-defined, catalytically relevant Ni complexes with Buchwald-type ligands exist. In this work, we report the analysis of Buchwald-type phosphine SRRs in four representative Ni-catalyzed cross-coupling reactions. Our study was guided by data-driven classification analysis, which together with mechanistic organometallic studies of structurally characterized Ni(0), Ni(I), and Ni(II) complexes allowed us to rationalize reactivity patterns in catalysis. Overall, we expect that this study will serve as a platform for further exploration of this ligand class in organonickel chemistry as well as in the development of new Ni-catalyzed cross-coupling methodologies.

[Ni(Np#)(η5-Cp)Cl]: Flexible, Sterically Bulky, Well-Defined, Highly Reactive Complex for Nickel-Catalyzed Cross-Coupling

Ni-NHCs (NHC = N-heterocyclic carbene) have become an increasingly important class of complexes in catalysis and organometallic chemistry owing to the beneficial features of nickel as an abundant 3d metal. However, the development of well-defined and air-stable Ni-NHC complexes for cross-coupling has been more challenging than with Pd-NHC catalysis because of less defined reactivity trends of NHC ancillary ligands coordinated to Ni. Herein, we report the synthesis and catalytic activity of well-defined [Ni(NHC)(η5-Cp)Cl] complexes bearing recently commercialized IPr# family of ligands (Sigma Aldrich) and versatile cyclopentadienyl throw-away ligand. The NHC ligands, IPr#, Np# and BIAN-IPr#, are prepared by robust and modular peralkylation of anilines. Most crucially, we identified [Ni(Np#)(η5-Cp)Cl] as a highly reactive [Ni(NHC)(η5-Cp)Cl] complex, with the reactivity outperforming the classical [Ni(IPr)(η5-Cp)Cl] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene). These [Ni(NHC)(η5-Cp)Cl] precatalysts were employed in the Suzuki and Kumada cross-coupling of aryl chlorides and aryl bromides. Computational studies were conducted to determine steric effect and bond order analysis. Considering the attractive features of well-defined Ni-NHCs, we anticipate that this class of bulky and flexible Ni-NHC catalysts will find broad application in organic synthesis and catalysis.

Palladium-catalyzed C-H trifluoromethylselenolation of arenes with [Me4N][SeCF3] and an oxidant

Trifluoromethylselenolation of arenes with [Me₄N][SeCF₃] in the presence of an oxidant through Pd-catalyzed C(sp²)-H activation under the assistance of a directing group is established for the first time. The reaction tolerates different directing groups and a variety of functional groups, enabling selective installation of a SeCF₃ moiety onto the ortho positions of arenes. Mechanistic studies revealed that the CF₃SeSeCF₃ intermediate in situ generated from oxidation of [Me₄N][SeCF₃] might be the real SeCF₃ reagent in the reaction.

Modular Generation of (Iodinated) Polyarenes Using Triethylgermane as Orthogonal Masking Group

While the modular construction of molecules from suitable building blocks is a powerful means to more rapidly generate a diversity of molecules than through customized syntheses, the further evolution of the underlying coupling methodology is key to realize widespread applications. We herein disclose a complementary modular coupling approach to the widely employed Suzuki coupling strategy of boron containing precursors, which relies on organogermane containing building blocks as key orthogonal functionality and an electrophilic (rather than nucleophilic) unmasking event paired with air-stable PdI dimer based bond construction. This allows to significantly shorten the reaction times for the iterative coupling steps and/or to close gaps in the accessible compound space, enabling straightforward access also to iodinated compounds.

Oxidative Addition of Aryl Halides to a Ni(I)-Bipyridine Complex

The oxidative addition of aryl halides to bipyridine- or phenanthroline-ligated nickel(I) is a commonly proposed step in nickel catalysis. However, there is a scarcity of complexes of this type that both are well-defined and undergo oxidative addition with aryl halides, hampering organometallic studies of this process. We report the synthesis of a well-defined Ni(I) complex, [(^CO2Etbpy)Ni^ICl]₄ (1). Its solution-phase speciation is characterized by a significant population of monomer and a redox equilibrium that can be perturbed by π-acceptors and σ-donors. 1 reacts readily with aryl bromides, and mechanistic studies are consistent with a pathway proceeding through an initial Ni(I) → Ni(III) oxidative addition to form a Ni(III) aryl species. Such a process was demonstrated stoichiometrically for the first time, affording a structurally characterized Ni(III) aryl complex.

Gold (I/III)-Catalyzed Trifluoromethylthiolation and Trifluoromethylselenolation of Organohalides

The first C-SCF3 /SeCF3 cross-coupling reactions using gold redox catalysis [(MeDalphos)AuCl], AgSCF3 or Me4 NSeCF3 , and organohalides as substrates are reported. The new methodology enables a one-stop shop synthesis of aryl/alkenyl/alkynyl trifluoromethylthio- and selenoethers with a broad substrate scope (>60 examples with up to 97 % isolated yield). The method is scalable, and its robustness is evidenced by the late-stage functionalization of various bioactive molecules, which makes this reaction an attractive alternative in the synthesis of trifluoromethylthio- and selenoethers for pharmaceutical and agrochemical research and development.

Ultrafast charge transfer dynamics in 2D covalent organic frameworks/Re-complex hybrid photocatalyst

Rhenium(I)-carbonyl-diimine complexes have emerged as promising photocatalysts for carbon dioxide reduction with covalent organic frameworks recognized as perfect sensitizers and scaffold support. Such Re complexes/covalent organic frameworks hybrid catalysts have demonstrated high carbon dioxide reduction activities but with strong excitation energy-dependence. In this paper, we rationalize this behavior by the excitation energy-dependent pathways of internal photo-induced charge transfer studied via transient optical spectroscopies and time-dependent density-functional theory calculation. Under band-edge excitation, the excited electrons are quickly injected from covalent organic frameworks moiety into catalytic Rhenium^I center within picosecond but followed by fast backward geminate recombination. While under excitation with high-energy photon, the injected electrons are located at high-energy levels in Rhenium^I centers with longer lifetime. Besides those injected electrons to Rhenium^I center, there still remain some long-lived electrons in covalent organic frameworks moiety which is transferred back from Rhenium^I. This facilitates the two-electron reaction of carbon dioxide conversion to carbon monoxide.

Re complexes within covalent organic frameworks have emerged as promising photocatalysts for CO₂ reduction. Here, authors identify a high-energy electron transfer pathway during CO₂ reduction that results in longer-lived excited states than a low-energy electron transfer pathway.

Designing Catalytic Systems Using Binary Solvent Mixtures: Impact of Mole Fraction of Water on Hydride Transfer

The free energy for hydride transfer reactions of transition metal hydrides is known to be influenced by solvent effects. The first-row transition metal hydride [HNi(dmpe)₂][BF₄] (dmpe = 1,2-bis(dimethylphosphino)ethane) has starkly different hydride transfer reactivities with CO₂ in different solvents. A binary mixture of water and acetonitrile was used to tune the hydride transfer reactivity of HNi(dmpe)₂⁺ with CO₂ so that the free energy for this reaction approached zero. Various mole fractions of water were tested and a linear relationship between the hydride transfer free energy and solvent composition was established for 0-0.24 mole fraction of water. A deviation from linearity was found upon moving toward higher mole fractions of water. The tuning of the free energy for hydride transfer allowed HNi(dmpe)₂⁺ to be used as a catalyst for the hydrogenation of CO₂. The optimized catalyst conditions produced 58 turnovers at room temperature in 0.082 mole fraction of water using 60 atm of a 1:1 mixture of H₂ to CO₂ gas.

Well-Defined NHC-Ni Complexes as Catalysts: Preparation, Structures and Mechanistic Studies in Cross-Coupling Reactions

Developmental studies are ongoing to discover a way to utilise new N-heterocyclic carbene (NHC)-Ni complexes as catalysts. Using a bulky NHC ligand, it is possible to synthesise an NHC/phosphine-mixed heteroleptic Ni(II) complex, which can serve as an excellent catalyst for various cross-coupling reactions. During the study of the reaction mechanisms using these Ni complexes, NHC-Ni(I) complexes were accidentally discovered, and it was observed that they exhibit excellent catalytic activity for cross-coupling reactions. The possibility of the presence of NHC-Ni(I) intermediates in these catalytic reaction pathways has been experimentally demonstrated. Depending on the type of reaction, dinuclear Ni(I) and mononuclear Ni(I) complexes can function as intermediates. The results of the investigation of each reaction mechanism are summarised, and the prospects are described.

Aromatic Trifluoromethylselenolation via Pd-catalyzed C-H functionalization

The synthesis of trifluoromethylselenolated aromatic molecules via an auxiliary-assisted, palladium catalyzed, C-H bonds functionalization with trifluoromethyl tolueneselenosulfonate as reagent is described. The mono- or bis-products can be preferentially formed. Some mechanistic investigations were realized to better understand the reaction. This methodology was also extended to fluoroalkylselenyl groups.

Synthesis and characterization of heteromultinuclear Ni/M clusters (M = Fe, Ru, W) including a paramagnetic (NHC)Ni-WCp*(CO)3 heterobinuclear complex

A diverse range of heteromultinuclear NiI/[MCO] clusters (MCO = CpFe(CO)2, CpRu(CO)2, Cp*W(CO)3) supported by a N-heterocyclic carbene ligand have been synthesized by reacting the NiI precursor, [IPrNi(μ-Cl)]2, with [MCO]- reagents under various conditions. Clusters with Ni2Fe2, NiFe2, Ni2Ru, Ni2Ru2, NiRu2, and Ni2W, and NiW cores were all characterized using NMR and IR spectroscopies and X-ray crystallography. The NiI-containing paramagnetic heterobinuclear species, IPrNi-Wp* (7), was further characterized by EPR spectroscopy and DFT calculations. Notably, unlike previously studied (NHC)CuI-[MCO] derivatives, complex 7 was found to coordinate Lewis bases like 3-chloropyridine to produce (IPr)(3-Clpy)NiWp* (9). Complex 9 further underwent thermolytic C-Cl activation, proposed to involve NHC-free [(3-Clpy)Ni(μ-Wp*)]2 (10), to provide the C-arylated N-heterocyclic carbene product, [IPr(py-3-yl)]+[Cp*WCl2(CO)2]- (11).

Selective Synthesis of Z-Silyl Enol Ethers via Ni-Catalyzed Remote Functionalization of Ketones

We report a remote functionalization strategy, which allows the Z-selective synthesis of silyl enol ethers of (hetero)aromatic and aliphatic ketones via Ni-catalyzed chain walking from a distant olefin site. The positional selectivity is controlled by the directionality of the chain walk and is independent of thermodynamic preferences of the resulting silyl enol ether. Our mechanistic data indicate that a Ni^(I) dimer is formed under these conditions, which serves as a catalyst resting state and, upon reaction with an alkyl bromide, is converted to [Ni^(II)-H] as an active chain-walking/functionalization catalyst, ultimately generating a stabilized η³-bound Ni^(II) enolate as the key selectivity-controlling intermediate.

Diversity-Oriented Synthesis of Aliphatic Fluorides via Reductive C(sp3 )-C(sp3 ) Cross-Coupling Fluoroalkylation

Monofluorinated alkyl compounds are of great importance in pharmaceuticals, agrochemicals and materials. Herein, we describe a direct nickel-catalyzed monofluoromethylation of unactivated alkyl halides using a low-cost industrial raw material, bromofluoromethane, by demonstrating a general and efficient reductive cross-coupling of two alkyl halides. Results with 1-bromo-1-fluoroalkane also demonstrate the viability of monofluoroalkylation, which further established the first example of reductive C(sp³ )-C(sp³ ) cross-coupling fluoroalkylation. These transformations demonstrate high efficiency, mild conditions, and excellent functional-group compatibility, especially for a range of pharmaceuticals and biologically active compounds. Mechanistic studies support a radical pathway. Kinetic studies reveal that the reaction is first-order dependent on catalyst and alkyl bromide whereas the generation of monofluoroalkyl radical is not involved in the rate-determining step. This strategy provides a general and efficient method for the synthesis of aliphatic fluorides.

Trifluoromethylselenolation and N-acylation of indoles with [Me4N][SeCF3]

An efficient method for oxidative trifluoromethylselenolation/N-acylation of indoles with excess [Me₄N][SeCF₃] in the presence of acyl peroxides and their derivatives is described. The reaction is easy to handle, proceeds smoothly at room temperature under metal-free conditions, and shows advantages such as good functional group tolerance, excellent regioselectivity, and compatibility of a number of substrates, producing 1-acyl and 3-trifluoromethylselanyl substituted indoles in good yields. Acyl peroxides and peroxycarboxylic acid behave as both oxidants and acyl sources in the transformation. This one-pot procedure provides a convenient access to a new class of indole derivatives, representing the first trifluoromethylselanyl bifunctionalization of indoles with the nucleophilic [Me₄N][SeCF₃] reagent.

Copper-Catalyzed Radical 1,2-Carbotrifluoromethylselenolation of Alkenes under Ambient Conditions

We have described a copper-catalyzed radical 1,2-carbotrifluoromethylselenolation of alkenes using the readily available alkyl halides and (Me₄N)SeCF₃ salt. Critical to the success is the use of a proline-based N,N,P-ligand to enhance the reducing capability of copper for easy conversion of diverse alkyl halides to the corresponding radicals via a single-electron transfer process. The reaction features a broad substrate scope, including various mono-, di-, and trisubstituted alkenes with many functional groups.

Forging C-SeCF3 Bonds with Trifluoromethyl Tolueneselenosulfonate under Visible-Light

This account highlights some of our recent work on photoinduced trifluoromethylselenolation reactions. This research program relies primarily on the design of a new key shelf-stable selenating reagent that can be involved in various radical processes In particular, we demonstrated that trifluoromethylselenolation of arenes, alkenes, alkynes as well as aliphatic organic building blocks can be readily achieved under visible-light irradiation. Mechanistic investigations based on ¹⁹ F NMR studies, EPR spectroscopy, cyclic voltammetry and luminescence studies allowed us to shed the light on the different proposed mechanisms in the designed methodologies. The applicative potential of these strategies was further demonstrated through the synthesis of bioactive analogue containing SeCF₃ motif.

Nickel-catalysed fluoromethylation reactions

This review highlights important developments in nickel-catalysed mono-, di- and tri-fluoromethylation, trifluoromethylthiolation and trifluoromethylselenolation.

Systematic Variation of Ligand and Cation Parameters Enables Site-Selective C-C and C-N Cross-Coupling of Multiply Chlorinated Arenes through Substrate-Ligand Electrostatic Interactions

Use of attractive noncovalent interactions between ligand and substrate is an emerging strategy for controlling positional selectivity. A key question relates to whether fine control on molecules with multiple, closely spaced reactive positions is achievable using typically less directional electrostatic interactions. Herein, we apply a 10-piece "toolkit" comprising of two closely related sulfonated phosphine ligands and five bases, each possessing varying cation size, to the challenge of site-selective cross-coupling of multiply chlorinated arenes. The fine tuning provided by these ligand/base combinations is effective for Suzuki-Miyaura coupling and Buchwald-Hartwig coupling on a range of isomeric dichlorinated and trichlorinated arenes, substrates that would produce intractable mixtures when typical ligands are used. This study develops a practical solution for site-selective cross-coupling to generate complex, highly substituted arenes.

A Next-Generation Air-Stable Palladium(I) Dimer Enables Olefin Migration and Selective C-C Coupling in Air

We report a new air-stable PdI dimer, [Pd(μ-I)(PCy2 t Bu)]2 , which triggers E-selective olefin migration to enamides and styrene derivatives in the presence of multiple functional groups and with complete tolerance of air. The same dimer also triggers extremely rapid C-C coupling (alkylation and arylation) at room temperature in a modular and triply selective fashion of aromatic C-Br, C-OTf/OFs, and C-Cl bonds in poly(pseudo)halogenated arenes, displaying superior activity over previous PdI dimer generations for substrates that bear substituents ortho to C-OTf.

Dialkyl Ether Formation at High-Valent Nickel

In this article, we investigated the I2-promoted cyclic dialkyl ether formation from 6-membered oxanickelacycles originally reported by Hillhouse. A detailed mechanistic investigation based on spectroscopic and crystallographic analysis revealed that a putative reductive elimination to forge C(sp3)-OC(sp3) using I2 might not be operative. We isolated a paramagnetic bimetallic NiIII intermediate featuring a unique Ni2(OR)2 (OR = alkoxide) diamond-like core complemented by a μ-iodo bridge between the two Ni centers, which remains stable at low temperatures, thus permitting its characterization by NMR, EPR, X-ray, and HRMS. At higher temperatures (>-10 °C), such bimetallic intermediate thermally decomposes to afford large amounts of elimination products together with iodoalkanols. Observation of the latter suggests that a C(sp3)-I bond reductive elimination occurs preferentially to any other challenging C-O bond reductive elimination. Formation of cyclized THF rings is then believed to occur through cyclization of an alcohol/alkoxide to the recently forged C(sp3)-I bond. The results of this article indicate that the use of F+ oxidants permits the challenging C(sp3)-OC(sp3) bond formation at a high-valent nickel center to proceed in good yields while minimizing deleterious elimination reactions. Preliminary investigations suggest the involvement of a high-valent bimetallic NiIII intermediate which rapidly extrudes the C-O bond product at remarkably low temperatures. The new set of conditions permitted the elusive synthesis of diethyl ether through reductive elimination, a remarkable feature currently beyond the scope of Ni.

Quaternary Ammonium Trifluoromethoxide Salts as Stable Sources of Nucleophilic OCF3

The reaction of nucleophilic tertiary amines with trifluoromethyl and pentafluoroethyl methyl ethers provides quaternary ammonium trifluoromethoxide (NR₄OCF₃) and pentafluoroethoxide (NR₄OCF₂CF₃) salts, respectively, in good yields. The new trifluoromethoxide salts disclosed herein are uniquely stable for extended periods of time in both the solid state and in solution, which complements contemporary reagents. Here we describe the preparation of a range of NR₄OCF₃ salts, their long-term stability, and utility in substitution reactions.

Facile Access to AgOCF3 and Its New Applications as a Reservoir for OCF2 for the Direct Synthesis of N-CF3 , Aryl or Alkyl Carbamoyl Fluorides

The development of innovative fluorination strategies is greatly dependent also on the availability, safety and practicability of available fluorinating reagents. We herein show a straightforward and quantitative strategy for the preparation of valuable AgOCF₃ at room temperature and showcase its performance in trifluoromethoxylations or as reservoir for O=CF₂ . This enabled the direct, practical and safe synthesis of valuable N-alkyl/aryl and N-CF₃ carbamoyl fluorides from secondary amines and isothiocyanides, respectively. Our mechanistic data indicate that AgOCF₃ does not liberate O=CF₂ until it is activated by a nucleophilic co-reagent, reinforcing the stability of the salt under our new preparation strategy.

Recent advances of dinuclear nickel- and palladium-complexes in homogeneous catalysis

In this highlight, we provide a current perspective of synthetic methodology development catalyzed by dinuclear Ni- and Pd-complexes in the past decade. The new catalytic reactivities of dinuclear Ni- and Pd-complexes are discussed.

Oxidative trifluoromethylselenolation of 1,3-dicarbonyls with [Me4N][SeCF3]

The first oxidative trifluoromethylchalcogenation of 1,3-dicarbonyls with [Me₄N][XCF₃] (X = Se and S) and an oxidant is described.

Copper-Catalyzed, N-Directed Csp3-H Trifluoromethylthiolation (-SCF3) and Trifluoromethylselenation (-SeCF3)

A direct and versatile copper-catalyzed trifluoromethylthiolation and trifluoromethylselenation of primary, secondary, and tertiary aliphatic C-H bonds was developed. The reaction provides direct access to molecules containing these emerging moieties in the presence of a wide range of common functional groups and in complex molecular environments.