Transition metals(TMs)are widely recognized for their valuable catalytic properties in various fields,from environmental protection to industrial application[1].Recently,there has been increasing interest in catalysts...Transition metals(TMs)are widely recognized for their valuable catalytic properties in various fields,from environmental protection to industrial application[1].Recently,there has been increasing interest in catalysts containing late TMs,particularly noble metals such as osmium,iridium and platinum.For instance,some studies have demonstrated that the Os atom serves as metal centers that coordinates alkanes,enabling the activation of C-H bonds in the first step[2].Characterization of the geometric and electronic structures of TM catalysts is essential for exploring the structure-reactivity relationship and elucidating complex mechanisms.展开更多
Dihydro-1-benzoyl-1,5-benzodiazepines react with (ethoxycarbonyl)carbenes to give 4H-azirino-[1,2-a][1,5]-benzodiazepines and unexpected new tin9 system 1H-pyrrolo-[1,2-a][1,5]-benzodiazepines. Dihydro-1,5-benzothiaze...Dihydro-1-benzoyl-1,5-benzodiazepines react with (ethoxycarbonyl)carbenes to give 4H-azirino-[1,2-a][1,5]-benzodiazepines and unexpected new tin9 system 1H-pyrrolo-[1,2-a][1,5]-benzodiazepines. Dihydro-1,5-benzothiazepines react with (ethoxycarbonyl)carbenes in cyclohexane to gire unexpected rin9 cleavage products ethyl (2E, 4E)-3-aryl-2-arylthiohexadienoates.展开更多
Despite the extraordinary success has been achieved in metal catalyst-promoted stereoselective ring-opening polymerization（ROP） of rac-lactide（rac-LA）, well-controlled stereoselective rac-LA ROP by organic catalys...Despite the extraordinary success has been achieved in metal catalyst-promoted stereoselective ring-opening polymerization（ROP） of rac-lactide（rac-LA）, well-controlled stereoselective rac-LA ROP by organic catalyst still remains a scientific challenge. Here we report our investigations into organocatalytic stereoselective ROP of rac-LA by utilizing novel bulky chiral and achiral N-heterocyclic carbenes（NHC）, 1,3-bis-（1′-naphthylethyl）imidazolin-2-ylidene. The effect of polymerization conditions（e.g. solvent, temperature, alcohol initiator） on ROP behavior by these bulky NHCs has been fully studied, leading to the formation of isotactic-rich stereoblock polylactide（Pi = 0.81） under optimized conditions with high activity（Conv. = 98% in 30 min） and narrow molecular weight dispersity（D = 1.05）.展开更多
A straightforward and efficient protocol for dearomatizing indoles is described.The reaction,catalyzed by an inexpensive Co(III)/Zn(II)catalyst,starts from easily accessible N‐pyrimidinyl indoles and ene‐yne ketones...A straightforward and efficient protocol for dearomatizing indoles is described.The reaction,catalyzed by an inexpensive Co(III)/Zn(II)catalyst,starts from easily accessible N‐pyrimidinyl indoles and ene‐yne ketones.Mild reaction conditions,high diastereoselectivity,a broad substrate scope,effective functional group tolerance,and reasonable to remarkable yields were observed.展开更多
We report the synthesis of dianionic OCO-supported NHC and MIC complexes of molybdenum and tungsten with the general formula(OCO)MO₂(OCO=bis-phenolate benzimidazolylidene M=Mo(1-Mo),bis-phenolate triazolylidene M=Mo(2...We report the synthesis of dianionic OCO-supported NHC and MIC complexes of molybdenum and tungsten with the general formula(OCO)MO₂(OCO=bis-phenolate benzimidazolylidene M=Mo(1-Mo),bis-phenolate triazolylidene M=Mo(2-Mo),M=W(2-W)and bis-phenolate imidazolylidene,M=Mo(3-Mo),W(3-W)).These complexes are tested in the catalytic deoxygenation of nitroarenes using pinacol as a sacrificial oxygen atom acceptor/reducing agent to examine the influence of the carbene and the metal centre in this transformation.The results show that the molybdenum-based triazolylidene complex 2-Mo is by far the most active catalyst,and TOFs of up to 270 h⁻¹ are observed,while the tungsten analogues are basically inactive.Mechanistic studies suggest that the superiority of the triazolylidene-based complex 2-Mo is a result of a highly stable metal carbene bond,strongly exceeding the stability of the other NHC complexes 1-Mo and 3-Mo.This is proven by the structural isolation of a triazolylidene pinacolate complex(5-Mo)that can be thermally converted to aμ-oxodimolybdenum(V)complex 7-Mo.The latter complex is very oxophilic and stoichiometrically deoxygenates nitro-and nitrosoarenes at room temperature.In contrast,azoarenes are not reductively cleaved by 7-Mo,suggesting direct deoxygenation of the nitroarenes to the corresponding anilines with nitrosoarenes as intermediates.In summary,this work showcases the superior influence of MIC donors on the catalytic properties of early transition metal complexes.展开更多
The increasingly environmental pollution have drawn global attentions to the development of new techniques that can effectively deal with the pollutants.With the unique set of electronic properties and structural dive...The increasingly environmental pollution have drawn global attentions to the development of new techniques that can effectively deal with the pollutants.With the unique set of electronic properties and structural diversities,N-heterocyclic carbenes(NHCs)and related materials are emerging as potential adsorbing materials for adsorptive decontamination of various pollutant-containing mediums.Recent investigations have revealed the feasibility of molecular and heterogeneous NHCs for adsorptive separation of harmful gases including CO_(2),CO,NO_(x),SO_(2),etc.Rather than simple gas trapping,NHCs functions as effective catalytic centers that activating and transforming the captured gas molecules.Besides,heterogeneous NHCs and their complexes have been applied to adsorptive removal of various organic pollutants and heavy metal ions from water solution with high efficiencies.These advancements have illustrated the significant potential of NHCs and their related materials in environmental decontamination.Instead of the well-known catalytic applications of NHCs in organic transformations,this review aims to offer an overview of the emerging applications of NHCs in the field of environmental decontamination and provide a comprehensive understanding of the mechanisms behind the N-heterocyclic carbene material-mediated environmental decontamination processes.With this in mind,the structure,synthesis,application,and performance of NHCs and related materials in environmental processes including gas separation and wastewater treatment are summarized,and the structure-activity relationship is discussed.Besides,the current challenge and future development of NHC-mediated environmental treatments are proposed.This review is expected to serve as a preliminary database for the environmental applications of NHC and related materials and offer deep insights into the rational design of novel NHC-based environmental materials for greener and efficient environmental processes.展开更多
Controlling the chirality of molecule-surface systems is essential for applications ranging from heterogeneous catalysis to biosensing.N-heterocyclic carbenes(NHCs)are quickly becoming a dominant ligand for noble meta...Controlling the chirality of molecule-surface systems is essential for applications ranging from heterogeneous catalysis to biosensing.N-heterocyclic carbenes(NHCs)are quickly becoming a dominant ligand for noble metal surface passivation,but the potential of chiral NHC scaffolds remains untapped.In this work,two stereoisomers,one C_(2) symmetric and one C_(s) symmetric,of saturated N-heterocyclic carbenes(NHCs)and a structurally related unsaturated NHC(C_(2v) symmetric)were synthesized as NHC-CO_(2) adducts.These CO_(2)-protected NHCs were deposited on gold films and their presence on the films was confirmed by laser desorption ionization mass spectrometry(LDI-MS)and surface enhanced Raman spectroscopy(SERS).Surprisingly,the C_(s) NHC,but not the chiral C_(2) NHC,partially degrades to the independently synthesized unsaturated NHC upon binding to the gold.Theoretical calculations assist in explaining this phenomenon by showing that the NHCs primarily lie flat on the gold surfaces,which exposes the backbone protons on the C_(s)-symmetric NHC to a formal elimination of H_(2),while the C_(2)-symmetric NHC remains protected from this elimination reaction.These results raise critical questions as to how the structure of NHC ligands may be tuned to influence binding and reactivity on gold surfaces.展开更多
Multifunctionalization reactions involving reactive intermediates offer powerful strategies for the rapid construction of complex molecules.Herein,we describe two trifunctionalization reactions of pyrazoleamide-derive...Multifunctionalization reactions involving reactive intermediates offer powerful strategies for the rapid construction of complex molecules.Herein,we describe two trifunctionalization reactions of pyrazoleamide-derived metal carbenes.Both transformations are proposed to proceed through a zwitterionic intermediate,formed via nucleophilic attack and pyrazole migration,followed by electrophilic trapping.This approach enables the efficient synthesis of 3-hydroxy-2-oxindole derivatives from isatins and amines in good yields,as well as chiralβ-aminoamide derivatives via a Rh/CPA co-catalytic system with excellent enantioselectivity.Importantly,both classes of compounds exhibited significant inhibitory activity against multiple tumor cell lines.展开更多
The functionalization of alkenes is a practical and important approach to access high value-added compounds.We herein realized the combination of energy transfer(EnT)and hydrogen atom transfer(HAT)process for the in s...The functionalization of alkenes is a practical and important approach to access high value-added compounds.We herein realized the combination of energy transfer(EnT)and hydrogen atom transfer(HAT)process for the in situ giving acyl azolium ions from the acyl electrophiles and N-heterocyclic carbenes(NHCs)catalysts under light irradiation,and developed three-component radical relay-type alkylacylation of readily available alkenes promoted by the cooperative NHC-photo cocatalysis to access structurally diversified alkylacylation products.The unique strategy for the NHC catalyst-bound acyl azoliums working as the intermolecular HAT reagent with the En T process was revealed.This protocol was also utilized to enable the late-stage functionalization of some important drugs and bioactive molecules.It featured readily bifunctionalization of alkenes,a wide range of alkenes and acyl imidazoles,mild reaction conditions,excellent selectivity,as well as broad functional group compatibility.Scale-up synthesis and a list of derivatization reactions displayed the potential synthetic application.Control experimental investigations and computational studies support that it involved the photoexcitation of in situ forming acyl azolium ions via En T process to access triplet diradical species with facile intersystem crossing,and acted as HAT reagents to undergo intermolecular HAT process,and then engaged in the following radical addition/radical-radical cross-coupling reaction with NHCs-linked radicals,resulting in alkylacylation products promoted by cooperative NHC and photocatalysis.展开更多
An efficient phospho-aldol reaction of aldehydes catalyzed by N-heterocyclic carbenes （NHCs） has been developed. With 10 mol% stable NHC 1,3-bis（2,6-diisopropylphenyl）imidazol-2-ylidene, various aldehydes reacted ...An efficient phospho-aldol reaction of aldehydes catalyzed by N-heterocyclic carbenes （NHCs） has been developed. With 10 mol% stable NHC 1,3-bis（2,6-diisopropylphenyl）imidazol-2-ylidene, various aldehydes reacted with dialkylphosphites smoothly to provide a-hydroxy phosphonates in 59%--99% yield. In this process, NHC was assumed to function as a carbon-centered bronsted base.展开更多
α-Imino metal carbenes are versatile intermediates in organic synthesis,and have broad applications in the assembly of divergent N-heterocycles.However,the catalytic enantioselective desymmetrization based onα-imino...α-Imino metal carbenes are versatile intermediates in organic synthesis,and have broad applications in the assembly of divergent N-heterocycles.However,the catalytic enantioselective desymmetrization based onα-imino metal carbenes has not been developed to date.Herein,we disclose an enantioselective desymmetrizing C(sp^(2))-H functionalization of azide-ynamides viaα-imino copper carbenes,leading to the efficient assembly of divergent chiral indoloazepines in generally moderate to excellent yields with high enantioselectivities.Notably,this reaction represents the first enantioselective desymmetrization based onα-imino metal carbenes.Further synthetic transformations and biological tests show the potential utility of this method.Moreover,computational studies are employed to elucidate the reaction mechanism and the origin of enantioselectivity.展开更多
Carbenes as one of the most important class of intermediates have been widely utilized in various organic synthetic transformations.Carbene insertion-initiated ring-opening reactions of cyclic ethers offer a valuable ...Carbenes as one of the most important class of intermediates have been widely utilized in various organic synthetic transformations.Carbene insertion-initiated ring-opening reactions of cyclic ethers offer a valuable strategy for constructing new carbon-oxygen bonds.In comparison with traditional thermal or metal-mediated carbene transfer reactions,visible-light-promoted multi-component reaction strategy provides a mild and eco-friendly approach to access densely functionalized molecules.Recently,visible-light-induced multi-component carbene transfer reactions of diazo compounds have been rapidly developed and attracted a great deal of research interest of chemists owing to their advantages of simple operation,mild condition,high atom economy and rich structural diversity.This paper summarizes the recent research progress on the visible-light-promoted multi-component carbene transfer reactions of diazo compounds via ring-opening of cyclic ethers with various nucleophiles.The reaction patterns of different nucleophiles and their corresponding mechanism are described in this review.The future research direction and challenges in this area are also discussed.展开更多
We report herein a class of superatomic AU13 clusters stabilized by different N-heterocyclic carbenes(NHCs).The clusters show diverse metal surface structures,properties and functions as exemplified by:(1)the first an...We report herein a class of superatomic AU13 clusters stabilized by different N-heterocyclic carbenes(NHCs).The clusters show diverse metal surface structures,properties and functions as exemplified by:(1)the first anionic AU13 cluster[Au1g(NHC-1)sBr6],which has bulky NHC-1 ligands that lead to a rather open metal surface contributing to its high catalytic activity;(2)the tricationic cluster[Au13(NHC-2)sBr2]+which has bidentate,benzyl-rich NHC-2 ligands that make it ultra-stable and highly-luminescent,suitable for bio-imaging;and(3)by bearing two pyridyl groups on NHC-3,the dicationic cluster[Au:a(NHC-3)gClg]f+exhibits reversible and stable visible absorption and solubility responses to protonation/deprotonation cycles,making it a potential pH sensor(NHC-1=1,3-disopropylbenzimidazolin-ylidene;NHC-2=1,3-bis(1-benzyl-1H-benzimidazol-1-ium-yl)propane;NHC-3=1,3-bis(icolyI)benzimidazolin-ylidene).The study nicely demonstrates the importance of ligands in designing metal nanoclusters with desired functionalities.展开更多
A pentagonal-prismatic cylinder[Ag5(L)2](PF6)5 obtained from the pentaphenylpyrrole-bridged pentaimidazolium salt H5-L(PF6)5 and AgI ions was determined by X-ray diffraction analyses.The target organometallic cylinder...A pentagonal-prismatic cylinder[Ag5(L)2](PF6)5 obtained from the pentaphenylpyrrole-bridged pentaimidazolium salt H5-L(PF6)5 and AgI ions was determined by X-ray diffraction analyses.The target organometallic cylinder not only exhibited enhanced fluorescence emission in dilute solution at room temperature but also showed an improved phosphorescence ratio compared with the free precursor and maintained a long lifetime(1.39 s)in the solid state at 77 K.Furthermore,the experimental results and DFT calculations confirmed that the formation of the organometallic cylinder promoted intersystem crossing.Meanwhile,the frontier orbitals of[Ag5(L)2](PF6)5 showed the main contribution of building block PPP as the luminescence source of[Ag5(L)2](PF6)5 by a modest heavy-atom effect.These results provide a strategy for constructing enhanced phosphorescent emission and long lifetime organometallic supramolecular phosphorescent materials.展开更多
1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orb...1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orbitals, but retain the way of the reaction. The reaction starts from the attack of the migrating hydrogen on the carbene p AO and ends with the entrance of the hydrogen into the carbene σ orbital. Reactivities are in the order of X=CH_2>NH>O. The reaction is exothermic or endothermic according to whether the product is a 4n+2 or 4n π electron molecule.展开更多
The block correlated coupled cluster (BCCC) method, with the complete active-space self-consistent-field (CASSCF) reference function, has been applied to investigating the singlet-triplet gaps in several substituted c...The block correlated coupled cluster (BCCC) method, with the complete active-space self-consistent-field (CASSCF) reference function, has been applied to investigating the singlet-triplet gaps in several substituted carbenes including four halocarbenes (CHCl, CF2, CCl2, and CBr2) and two hydroxycar-benes (CHOH and C(OH)2). A comparison of our results with the experimental data and other theoretical estimates shows that the present approach can provide quantitative descriptions for all the studied carbenes. It is demonstrated that the CAS-BCCC method is a promising theoretical tool for calculating the electronic structures of diradicals.展开更多
Copper-hydrides have been intensively studied for a long time due to their utilization in a variety of technologically important chemical transformations.Nevertheless,poor stability of the species severely hinders its...Copper-hydrides have been intensively studied for a long time due to their utilization in a variety of technologically important chemical transformations.Nevertheless,poor stability of the species severely hinders its isolation,storage and operation,which is worse for nano-sized ones.We report here an unprecedented strategy to access to ultrastable copper-hydride nanoclusters(NCs),namely,using bidentate N-heterocyclic carbenes as stabilizing ligands in addition to thiolates.In this work,a simple synthetic protocol was developed to synthesize the first large copper-hydride nanoclusters(NCs)stabilized by N-heterocyclic carbenes(NHCs).The NC,with the formula of Cu3i(RS)25(NHC)3H6(NHC=1,4-bis(1-benzyl-1 H-benzimidazol-1-ium-3-yl)butane,RS=4-fluorothiophenol),was fully characterized by high resolution Fourier transform ion cyclotron resonance mass spectrum,nuclear magnetic resonance,ultra-violet visible spectroscopy,density functional theory(DFT)calculations and single-crystal X-ray crystallography.Structurally,the title cluster exhibits unprecedented Cu4 tetrahedron-based vertex-sharing(TBVS)superstructure(fusion of six Cu4 tetrahedra).Moreover,the ultrahigh thermal stability renders the cluster a model system to highlight the power of NHCs(even other carbenes)in controlling geometrical,electronic and surface structure of polyhydrido copper clusters.展开更多
The steric and electronic properties of A/-heterocyclic carbenes(NHCs)can be modified by the exocyclic substituents at the nitrogen atoms,by 1-3 atoms'replacements of the five-membered imidazolium skeleton and by ...The steric and electronic properties of A/-heterocyclic carbenes(NHCs)can be modified by the exocyclic substituents at the nitrogen atoms,by 1-3 atoms'replacements of the five-membered imidazolium skeleton and by the changes of the backbones.Herein,we report the usage of nido-C_(2)B_(3) carbora ne anions as the backb ones of NHCs.Stirring the mixture of sec on dary amino o-carbora nes(lb-le),triethyl orthoformate and HBF4-Et2O results in the unexpected cage-opening of o-carboranes to afford the n/do-C_(2)B_(9) carbora ne anions supported A/-heterocyclic carbene precursors(4b-4e).Deprotonation of 4b with sodium hexamethyldisilazide at-78℃ affords the/V-heterocyclic carbene ligand,which was used to form an Au(I)NHC complex(5).DFT calculations revealed a high-lying lone pair orbitals of the carbene ligands,predicting their strong o-donating abilities.展开更多
Addition of dihalocarbene with olefin is the most important method to prepare the derivatives of gem-dihalocyclopropanes. Up till now, the method reported by Makosza in 1969, which is α-elimination of haloform by str...Addition of dihalocarbene with olefin is the most important method to prepare the derivatives of gem-dihalocyclopropanes. Up till now, the method reported by Makosza in 1969, which is α-elimination of haloform by strong base under phase transfer catalysis, is the most widely used one in the generation of dihalocarbenes. But it would cause the side reaction of groups in olefin molecules, which are sensitive to bases. Besides, haloform, 3—10 equivalents of olefin, is used to act as a solvent, so it is impossible to control the展开更多
The isomerizations and decompositions of carbenoids H_2C=CLiCl and H_2CLiCl have been studied by use of HF/STO-3G gradient method. Three equilibrium structures of H_2C=CLiCl were obtained, in which the linear structur...The isomerizations and decompositions of carbenoids H_2C=CLiCl and H_2CLiCl have been studied by use of HF/STO-3G gradient method. Three equilibrium structures of H_2C=CLiCl were obtained, in which the linear structure has the lowest energy and the askew substituted structure was the next. It is found that the decomposition of H_2C=CLiCl undergoes a concerted FBW rearrangement and the inversion barrier of its askew substituted structure is 36 kJ/mol. For H_2CLiCl, the askew substituted structure, extending all valences of the carbon into a single hemisphere, is the lowest energy and its inversion barrier is 87 kJ/mol. The discussions on the factors concerned with the structural stabilities are given in this paper.展开更多
基金supported by the National Natural Science Foundation of China(22273101,22125303,92361302,22373102,21327901,and 22288201)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2020187)+3 种基金the Innovation Program for Quantum Science and Technology(2021Z D0303304)the International Partnership Program of the Chinese Academy of Sciences(121421KYSB20170012)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(GJJS TD20220001)Dalian Institute of Chemical Physics(DICP I202437).
文摘Transition metals(TMs)are widely recognized for their valuable catalytic properties in various fields,from environmental protection to industrial application[1].Recently,there has been increasing interest in catalysts containing late TMs,particularly noble metals such as osmium,iridium and platinum.For instance,some studies have demonstrated that the Os atom serves as metal centers that coordinates alkanes,enabling the activation of C-H bonds in the first step[2].Characterization of the geometric and electronic structures of TM catalysts is essential for exploring the structure-reactivity relationship and elucidating complex mechanisms.
文摘Dihydro-1-benzoyl-1,5-benzodiazepines react with (ethoxycarbonyl)carbenes to give 4H-azirino-[1,2-a][1,5]-benzodiazepines and unexpected new tin9 system 1H-pyrrolo-[1,2-a][1,5]-benzodiazepines. Dihydro-1,5-benzothiazepines react with (ethoxycarbonyl)carbenes in cyclohexane to gire unexpected rin9 cleavage products ethyl (2E, 4E)-3-aryl-2-arylthiohexadienoates.
基金financially supported by the Science and Technology Commission of Shanghai Municipality(No.17JC1401200)
文摘Despite the extraordinary success has been achieved in metal catalyst-promoted stereoselective ring-opening polymerization（ROP） of rac-lactide（rac-LA）, well-controlled stereoselective rac-LA ROP by organic catalyst still remains a scientific challenge. Here we report our investigations into organocatalytic stereoselective ROP of rac-LA by utilizing novel bulky chiral and achiral N-heterocyclic carbenes（NHC）, 1,3-bis-（1′-naphthylethyl）imidazolin-2-ylidene. The effect of polymerization conditions（e.g. solvent, temperature, alcohol initiator） on ROP behavior by these bulky NHCs has been fully studied, leading to the formation of isotactic-rich stereoblock polylactide（Pi = 0.81） under optimized conditions with high activity（Conv. = 98% in 30 min） and narrow molecular weight dispersity（D = 1.05）.
文摘A straightforward and efficient protocol for dearomatizing indoles is described.The reaction,catalyzed by an inexpensive Co(III)/Zn(II)catalyst,starts from easily accessible N‐pyrimidinyl indoles and ene‐yne ketones.Mild reaction conditions,high diastereoselectivity,a broad substrate scope,effective functional group tolerance,and reasonable to remarkable yields were observed.
基金funded in whole or in part by the Austrian Science Fund(FWF),Grant-DOI:https://doi.org/10.55776/P34626.
文摘We report the synthesis of dianionic OCO-supported NHC and MIC complexes of molybdenum and tungsten with the general formula(OCO)MO₂(OCO=bis-phenolate benzimidazolylidene M=Mo(1-Mo),bis-phenolate triazolylidene M=Mo(2-Mo),M=W(2-W)and bis-phenolate imidazolylidene,M=Mo(3-Mo),W(3-W)).These complexes are tested in the catalytic deoxygenation of nitroarenes using pinacol as a sacrificial oxygen atom acceptor/reducing agent to examine the influence of the carbene and the metal centre in this transformation.The results show that the molybdenum-based triazolylidene complex 2-Mo is by far the most active catalyst,and TOFs of up to 270 h⁻¹ are observed,while the tungsten analogues are basically inactive.Mechanistic studies suggest that the superiority of the triazolylidene-based complex 2-Mo is a result of a highly stable metal carbene bond,strongly exceeding the stability of the other NHC complexes 1-Mo and 3-Mo.This is proven by the structural isolation of a triazolylidene pinacolate complex(5-Mo)that can be thermally converted to aμ-oxodimolybdenum(V)complex 7-Mo.The latter complex is very oxophilic and stoichiometrically deoxygenates nitro-and nitrosoarenes at room temperature.In contrast,azoarenes are not reductively cleaved by 7-Mo,suggesting direct deoxygenation of the nitroarenes to the corresponding anilines with nitrosoarenes as intermediates.In summary,this work showcases the superior influence of MIC donors on the catalytic properties of early transition metal complexes.
基金supported by the National Natural Science Foundation of China(grant numbers 22202099 and 22472177)Natural Science Foundation of Hunan Province(grant numbers 2022JJ40366 and 2022JJ40351)the Scientific Research Foundation of Hunan Provincial Education Department(grant numbers 23A0332 and 21B0440).
文摘The increasingly environmental pollution have drawn global attentions to the development of new techniques that can effectively deal with the pollutants.With the unique set of electronic properties and structural diversities,N-heterocyclic carbenes(NHCs)and related materials are emerging as potential adsorbing materials for adsorptive decontamination of various pollutant-containing mediums.Recent investigations have revealed the feasibility of molecular and heterogeneous NHCs for adsorptive separation of harmful gases including CO_(2),CO,NO_(x),SO_(2),etc.Rather than simple gas trapping,NHCs functions as effective catalytic centers that activating and transforming the captured gas molecules.Besides,heterogeneous NHCs and their complexes have been applied to adsorptive removal of various organic pollutants and heavy metal ions from water solution with high efficiencies.These advancements have illustrated the significant potential of NHCs and their related materials in environmental decontamination.Instead of the well-known catalytic applications of NHCs in organic transformations,this review aims to offer an overview of the emerging applications of NHCs in the field of environmental decontamination and provide a comprehensive understanding of the mechanisms behind the N-heterocyclic carbene material-mediated environmental decontamination processes.With this in mind,the structure,synthesis,application,and performance of NHCs and related materials in environmental processes including gas separation and wastewater treatment are summarized,and the structure-activity relationship is discussed.Besides,the current challenge and future development of NHC-mediated environmental treatments are proposed.This review is expected to serve as a preliminary database for the environmental applications of NHC and related materials and offer deep insights into the rational design of novel NHC-based environmental materials for greener and efficient environmental processes.
基金supported by the National Science Foundation under Grants CHE-2108328(G.K.,P.N.,and D.M.J.)CHE-2108330(N.L.D.,R.L.T.,and J.P.C.)+1 种基金CHE-1856419CHE-2312222(G.H.and L.J.)。
文摘Controlling the chirality of molecule-surface systems is essential for applications ranging from heterogeneous catalysis to biosensing.N-heterocyclic carbenes(NHCs)are quickly becoming a dominant ligand for noble metal surface passivation,but the potential of chiral NHC scaffolds remains untapped.In this work,two stereoisomers,one C_(2) symmetric and one C_(s) symmetric,of saturated N-heterocyclic carbenes(NHCs)and a structurally related unsaturated NHC(C_(2v) symmetric)were synthesized as NHC-CO_(2) adducts.These CO_(2)-protected NHCs were deposited on gold films and their presence on the films was confirmed by laser desorption ionization mass spectrometry(LDI-MS)and surface enhanced Raman spectroscopy(SERS).Surprisingly,the C_(s) NHC,but not the chiral C_(2) NHC,partially degrades to the independently synthesized unsaturated NHC upon binding to the gold.Theoretical calculations assist in explaining this phenomenon by showing that the NHCs primarily lie flat on the gold surfaces,which exposes the backbone protons on the C_(s)-symmetric NHC to a formal elimination of H_(2),while the C_(2)-symmetric NHC remains protected from this elimination reaction.These results raise critical questions as to how the structure of NHC ligands may be tuned to influence binding and reactivity on gold surfaces.
基金the National Natural Science Foundation of China(92256301)Guangdong Provincial Key Laboratory of Chiralmoleculeand Drug Discovery(2023B1212060022)+2 种基金Natural Science Foundation of Guangdong Province(2023A1515011486)Key-Area Research and Development Program of Guangdong Province(2022B1111050003,2022B1111070004)the open project of the Key Laboratory of Xinjiang Native Medicinal and Edible Plant Resources Chemistry(KSUZDSYS202401)is greatly acknowledged.
文摘Multifunctionalization reactions involving reactive intermediates offer powerful strategies for the rapid construction of complex molecules.Herein,we describe two trifunctionalization reactions of pyrazoleamide-derived metal carbenes.Both transformations are proposed to proceed through a zwitterionic intermediate,formed via nucleophilic attack and pyrazole migration,followed by electrophilic trapping.This approach enables the efficient synthesis of 3-hydroxy-2-oxindole derivatives from isatins and amines in good yields,as well as chiralβ-aminoamide derivatives via a Rh/CPA co-catalytic system with excellent enantioselectivity.Importantly,both classes of compounds exhibited significant inhibitory activity against multiple tumor cell lines.
基金supported by the Fundamental Research Funds for the Central Universities(2042025kf0032)the National Natural Science Foundation of China(22271226,22171134,22071186,22071187)+1 种基金the National Key R&D Program of China(2023YFA1506700)the National Youth Talent Support Program。
文摘The functionalization of alkenes is a practical and important approach to access high value-added compounds.We herein realized the combination of energy transfer(EnT)and hydrogen atom transfer(HAT)process for the in situ giving acyl azolium ions from the acyl electrophiles and N-heterocyclic carbenes(NHCs)catalysts under light irradiation,and developed three-component radical relay-type alkylacylation of readily available alkenes promoted by the cooperative NHC-photo cocatalysis to access structurally diversified alkylacylation products.The unique strategy for the NHC catalyst-bound acyl azoliums working as the intermolecular HAT reagent with the En T process was revealed.This protocol was also utilized to enable the late-stage functionalization of some important drugs and bioactive molecules.It featured readily bifunctionalization of alkenes,a wide range of alkenes and acyl imidazoles,mild reaction conditions,excellent selectivity,as well as broad functional group compatibility.Scale-up synthesis and a list of derivatization reactions displayed the potential synthetic application.Control experimental investigations and computational studies support that it involved the photoexcitation of in situ forming acyl azolium ions via En T process to access triplet diradical species with facile intersystem crossing,and acted as HAT reagents to undergo intermolecular HAT process,and then engaged in the following radical addition/radical-radical cross-coupling reaction with NHCs-linked radicals,resulting in alkylacylation products promoted by cooperative NHC and photocatalysis.
基金the National Natural Science Foundation of China，the Team Innovation Project of Shihezi University
文摘An efficient phospho-aldol reaction of aldehydes catalyzed by N-heterocyclic carbenes （NHCs） has been developed. With 10 mol% stable NHC 1,3-bis（2,6-diisopropylphenyl）imidazol-2-ylidene, various aldehydes reacted with dialkylphosphites smoothly to provide a-hydroxy phosphonates in 59%--99% yield. In this process, NHC was assumed to function as a carbon-centered bronsted base.
基金supported by the National Natural Science Foundation of China(22331004,22125108 and 22121001)the National Fund for Fostering Talents of Basic Science NFFTBS(J1310024)。
文摘α-Imino metal carbenes are versatile intermediates in organic synthesis,and have broad applications in the assembly of divergent N-heterocycles.However,the catalytic enantioselective desymmetrization based onα-imino metal carbenes has not been developed to date.Herein,we disclose an enantioselective desymmetrizing C(sp^(2))-H functionalization of azide-ynamides viaα-imino copper carbenes,leading to the efficient assembly of divergent chiral indoloazepines in generally moderate to excellent yields with high enantioselectivities.Notably,this reaction represents the first enantioselective desymmetrization based onα-imino metal carbenes.Further synthetic transformations and biological tests show the potential utility of this method.Moreover,computational studies are employed to elucidate the reaction mechanism and the origin of enantioselectivity.
基金Science and Technology Foundation of Guizhou Province(No.QKHJC-ZK[2024]654)Guizhou Provincial University Key Laboratory of Advanced Functional Electronic Materials(No.QJJ[2023]021).
文摘Carbenes as one of the most important class of intermediates have been widely utilized in various organic synthetic transformations.Carbene insertion-initiated ring-opening reactions of cyclic ethers offer a valuable strategy for constructing new carbon-oxygen bonds.In comparison with traditional thermal or metal-mediated carbene transfer reactions,visible-light-promoted multi-component reaction strategy provides a mild and eco-friendly approach to access densely functionalized molecules.Recently,visible-light-induced multi-component carbene transfer reactions of diazo compounds have been rapidly developed and attracted a great deal of research interest of chemists owing to their advantages of simple operation,mild condition,high atom economy and rich structural diversity.This paper summarizes the recent research progress on the visible-light-promoted multi-component carbene transfer reactions of diazo compounds via ring-opening of cyclic ethers with various nucleophiles.The reaction patterns of different nucleophiles and their corresponding mechanism are described in this review.The future research direction and challenges in this area are also discussed.
基金the National Key R&D Program of China(No.2017YFA0207304)the National Nautural Science Foundation of China(Nos.21890752,21731005,21802109,and 21721001)the fundamental research funds for central universities(No.20720190043)for financial support.
文摘We report herein a class of superatomic AU13 clusters stabilized by different N-heterocyclic carbenes(NHCs).The clusters show diverse metal surface structures,properties and functions as exemplified by:(1)the first anionic AU13 cluster[Au1g(NHC-1)sBr6],which has bulky NHC-1 ligands that lead to a rather open metal surface contributing to its high catalytic activity;(2)the tricationic cluster[Au13(NHC-2)sBr2]+which has bidentate,benzyl-rich NHC-2 ligands that make it ultra-stable and highly-luminescent,suitable for bio-imaging;and(3)by bearing two pyridyl groups on NHC-3,the dicationic cluster[Au:a(NHC-3)gClg]f+exhibits reversible and stable visible absorption and solubility responses to protonation/deprotonation cycles,making it a potential pH sensor(NHC-1=1,3-disopropylbenzimidazolin-ylidene;NHC-2=1,3-bis(1-benzyl-1H-benzimidazol-1-ium-yl)propane;NHC-3=1,3-bis(icolyI)benzimidazolin-ylidene).The study nicely demonstrates the importance of ligands in designing metal nanoclusters with desired functionalities.
基金supported by the National Natural Science Foundation of China(22025107)the National Youth Top-notch Talent Support Program of China,Xi'an Key Laboratory of Functional Supramolecular Structure and Materialsthe FM&EM International Joint Laboratory of Northwest University.
文摘A pentagonal-prismatic cylinder[Ag5(L)2](PF6)5 obtained from the pentaphenylpyrrole-bridged pentaimidazolium salt H5-L(PF6)5 and AgI ions was determined by X-ray diffraction analyses.The target organometallic cylinder not only exhibited enhanced fluorescence emission in dilute solution at room temperature but also showed an improved phosphorescence ratio compared with the free precursor and maintained a long lifetime(1.39 s)in the solid state at 77 K.Furthermore,the experimental results and DFT calculations confirmed that the formation of the organometallic cylinder promoted intersystem crossing.Meanwhile,the frontier orbitals of[Ag5(L)2](PF6)5 showed the main contribution of building block PPP as the luminescence source of[Ag5(L)2](PF6)5 by a modest heavy-atom effect.These results provide a strategy for constructing enhanced phosphorescent emission and long lifetime organometallic supramolecular phosphorescent materials.
基金This project was supported by the National Natural Science Foundation of China.
文摘1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orbitals, but retain the way of the reaction. The reaction starts from the attack of the migrating hydrogen on the carbene p AO and ends with the entrance of the hydrogen into the carbene σ orbital. Reactivities are in the order of X=CH_2>NH>O. The reaction is exothermic or endothermic according to whether the product is a 4n+2 or 4n π electron molecule.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20625309 and 20433020)the National Basic Research Program (Grant No. 2004CB719901)+1 种基金the Ministry of Education of China (Grant No. NCET-04-0450) Fok Ying Tong Education Foundation (Grant No. 91014)
文摘The block correlated coupled cluster (BCCC) method, with the complete active-space self-consistent-field (CASSCF) reference function, has been applied to investigating the singlet-triplet gaps in several substituted carbenes including four halocarbenes (CHCl, CF2, CCl2, and CBr2) and two hydroxycar-benes (CHOH and C(OH)2). A comparison of our results with the experimental data and other theoretical estimates shows that the present approach can provide quantitative descriptions for all the studied carbenes. It is demonstrated that the CAS-BCCC method is a promising theoretical tool for calculating the electronic structures of diradicals.
基金the National Key R&D Program of China(No.2017YFA0207302)the National Natural Science Foundation of China(Nos.21890752,21731005,21420102001,and 21721001)and the 111 Project(No.B08027)for financial supportsupported by the Academy of Finland through HHs Academy Professorship and grants 292352,319208.
文摘Copper-hydrides have been intensively studied for a long time due to their utilization in a variety of technologically important chemical transformations.Nevertheless,poor stability of the species severely hinders its isolation,storage and operation,which is worse for nano-sized ones.We report here an unprecedented strategy to access to ultrastable copper-hydride nanoclusters(NCs),namely,using bidentate N-heterocyclic carbenes as stabilizing ligands in addition to thiolates.In this work,a simple synthetic protocol was developed to synthesize the first large copper-hydride nanoclusters(NCs)stabilized by N-heterocyclic carbenes(NHCs).The NC,with the formula of Cu3i(RS)25(NHC)3H6(NHC=1,4-bis(1-benzyl-1 H-benzimidazol-1-ium-3-yl)butane,RS=4-fluorothiophenol),was fully characterized by high resolution Fourier transform ion cyclotron resonance mass spectrum,nuclear magnetic resonance,ultra-violet visible spectroscopy,density functional theory(DFT)calculations and single-crystal X-ray crystallography.Structurally,the title cluster exhibits unprecedented Cu4 tetrahedron-based vertex-sharing(TBVS)superstructure(fusion of six Cu4 tetrahedra).Moreover,the ultrahigh thermal stability renders the cluster a model system to highlight the power of NHCs(even other carbenes)in controlling geometrical,electronic and surface structure of polyhydrido copper clusters.
基金support from the National Natural Science Foundation of China(Grant No.21771048)the Natural Science Foundation of Zhejiang Provinee(Grant No.LY17B010002).
文摘The steric and electronic properties of A/-heterocyclic carbenes(NHCs)can be modified by the exocyclic substituents at the nitrogen atoms,by 1-3 atoms'replacements of the five-membered imidazolium skeleton and by the changes of the backbones.Herein,we report the usage of nido-C_(2)B_(3) carbora ne anions as the backb ones of NHCs.Stirring the mixture of sec on dary amino o-carbora nes(lb-le),triethyl orthoformate and HBF4-Et2O results in the unexpected cage-opening of o-carboranes to afford the n/do-C_(2)B_(9) carbora ne anions supported A/-heterocyclic carbene precursors(4b-4e).Deprotonation of 4b with sodium hexamethyldisilazide at-78℃ affords the/V-heterocyclic carbene ligand,which was used to form an Au(I)NHC complex(5).DFT calculations revealed a high-lying lone pair orbitals of the carbene ligands,predicting their strong o-donating abilities.
文摘Addition of dihalocarbene with olefin is the most important method to prepare the derivatives of gem-dihalocyclopropanes. Up till now, the method reported by Makosza in 1969, which is α-elimination of haloform by strong base under phase transfer catalysis, is the most widely used one in the generation of dihalocarbenes. But it would cause the side reaction of groups in olefin molecules, which are sensitive to bases. Besides, haloform, 3—10 equivalents of olefin, is used to act as a solvent, so it is impossible to control the
文摘The isomerizations and decompositions of carbenoids H_2C=CLiCl and H_2CLiCl have been studied by use of HF/STO-3G gradient method. Three equilibrium structures of H_2C=CLiCl were obtained, in which the linear structure has the lowest energy and the askew substituted structure was the next. It is found that the decomposition of H_2C=CLiCl undergoes a concerted FBW rearrangement and the inversion barrier of its askew substituted structure is 36 kJ/mol. For H_2CLiCl, the askew substituted structure, extending all valences of the carbon into a single hemisphere, is the lowest energy and its inversion barrier is 87 kJ/mol. The discussions on the factors concerned with the structural stabilities are given in this paper.
