Palladacycles remain a challenging and significant research field in organic chemistry and have emerged as a type of powerful and versatile precatalysts or key active intermediates for transition metal catalysis.These...Palladacycles remain a challenging and significant research field in organic chemistry and have emerged as a type of powerful and versatile precatalysts or key active intermediates for transition metal catalysis.These achievements in this area are correlated to the design and development of useful ancillary ligands,such as N-heterocyclic carbenes(NHCs),which not only stabilize the actual catalytic active species facilitating the transformations,but also provide additional control over the selectivity of reactions.In this context,NHCs-ligated palladacycles(NHCP_(dcycles))with different electronic and steric properties have been synthesized and applied as green precatalysts(high stability and activity,low catalyst loading and mild reaction conditions)to accelerate transition metalcatalyzed reactions.Therefore,this review focuses mainly on the strategy of NHC-Pd_(cycles) design and catalytic results obtained from representative transition metal catalysis,such as Suzuki-Miyaura,Heck-Mizoroki and Sonogashira cross-coupling reactions,Buchwald-Hartwig amination,carbonylation as well as arylation.At last,the current limitations and potential trends for further development of NHC-Pdcycles are also highlighted.展开更多
Herein,we present a method for the homogeneous hydrogenation of nitroarenes to produce anilines using low catalyst loading(1 mo%)of copper N-heterocyclic carbene complexes as the catalyst and ammonia borane as the sou...Herein,we present a method for the homogeneous hydrogenation of nitroarenes to produce anilines using low catalyst loading(1 mo%)of copper N-heterocyclic carbene complexes as the catalyst and ammonia borane as the source of hydrogen.A wide range of nitroarenes,featuring diverse functional groups,were selectively transformed into their corresponding primary aromatic amines with high yields.This process can be readily scaled up and exhibits compatibility with various sensitive functional groups,including halogen,trifluoromethyl,aminomethyl,alkenyl,cyano,ester,amide,and hydroxyl.Notably,this catalytic methodology finds application in the synthesis of essential drug compounds.Mechanistic investigations suggest that the in-situ-generated Cu-H species may serve as active intermediates,with reduction pathways involving species such as azobenzene,1,2-diphenylhydrazine,nitrosobenzene,and N-phenylhydroxylamine.展开更多
The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with V...The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with VOCl_(3).The total isolated yield of VOCl_(3)[1,3-(2,4,6-Me_(3)C_(6)H_(2))_(2)(NCH=)_(2)C:](V4') reached 86% by transmetallation reaction,which is much higher than that(48%) by direct coordination method.This methodology has also been used to synthesize the novel vanadium complexes containing unsymmetrical NHC ligands of VOCl_(3)[PhCH_(2)NCH=CHNR)C:](V5',R=2,4,6-Me_(3)C_(6)H_(2);V6',R=2,4-Me_(2)-6-Ph-C_(6)H_(2);V7',R=2,6-^(i)Pr_(2)-C_(6)H_(3)) with high yield,which could not be obtained by direct coordination method.The catalytic activity and copolymerization ability would be improved by introducing unsymmetrical NHC ligands due to their less steric bulky effect.The vanadium complex V5' containing unsymmetrical NHC ligand exhibits higher catalytic activity(3.7×10^(5)g_(copolymer)·mol^(-1) of V·h^(-1)) than that of V4' containing symmetrical NHC ligand.Moreover,the higher propylene incorporation ratio(45.6 mol%) in the copolymers of ethylene with propylene could be obtained by using V5' than that(39.9%) by using V4'.The results would provide a highly efficient strategy for the synthesis of early transition metal complexes containing versitile NHC ligands,affording the catalyst with both high catalytic activity and copolymerization ability for the synthesis of high performance polyolefin elastomers.展开更多
Thermally stable, solid-state luminescent organic materials are highly desired for the development of practical applications.Herein we synthesized new gold(I) complexes with N-heterocyclic carbene ligands, which have ...Thermally stable, solid-state luminescent organic materials are highly desired for the development of practical applications.Herein we synthesized new gold(I) complexes with N-heterocyclic carbene ligands, which have the ability to form strong metalorganic bond. Consequently, their thermochemical stability is enhanced at temperatures around 300 °C. Precise design of the molecular structure of the ligands, with a focus on ensuring low steric hindrance around Au atoms in order to limit disturbances to Au/Au interactions, provided a complex with a densely packed crystal with a shorter intermolecular Au–Au distance(3.17 ?)than the typical distance. In the solid state, this complex exhibited strong aurophilic interactions, which generated intense phosphorescence even in air at room temperature(quantum yield=16%) in spite of absence of any phosphorescence in solution.This behavior is characteristic for solid-state luminescence referred to as aggregation-controlled emission. Furthermore, the gold(I) complex displays capacity for mechano-and vapo-chromism—that is, the ability to change color reversibly in response to the application of external stimuli. We believe that the proposed design framework, which involves controlling thermal stability and luminescence property separately, provides a new opportunity for the development of practical applications using solid-state luminescent organic molecules.展开更多
Three cobalt complexes bearing tunable,redox-active bipyridyl N-heterocyclic carbene(NHC)-based ligands have been studied for electrocatalytic hydrogen evolution from aqueous solutions.The effect of structural modific...Three cobalt complexes bearing tunable,redox-active bipyridyl N-heterocyclic carbene(NHC)-based ligands have been studied for electrocatalytic hydrogen evolution from aqueous solutions.The effect of structural modifications to the ligand framework is investigated across the catalyst series,which includes a non-macrocyclic derivative(1-Co)and 16-(2-Co)and 15-(3-Co)membered macrocycles.A structure-activity relationship is demonstrated,in which the macrocyclic complexes have greater activity compared to their non-macrocyclic counterpart with the most rigid catalyst,supported by the 15-membered macrocycle,performing best overall.Indeed,3-Co catalyzes H2 evolution from aqueous pH 4 acetate buffer with a Faradaic efficiency of 97%at a low overpotential of 330 mV.Mechanistic studies are consistent with formation of a cobalt-hydride species that is subsequently protonated to evolve H2 via a heterolytic pathway.展开更多
While nickel(II)complexes have been widely used as catalysts for carbon-carbon coupling reactions,the exploration of their photophysical and photochemical properties is still in the infancy.Here,a series of square-pla...While nickel(II)complexes have been widely used as catalysts for carbon-carbon coupling reactions,the exploration of their photophysical and photochemical properties is still in the infancy.Here,a series of square-planar Ni(II)complexes[(diNHC)NiX2]bearing chelating benzimidazole-based bis(N-heterocyclic carbene)ligands and varying anionic coligands(1,X=Cl;2,X=Br;3,X=I)are synthesized and structurally characterized.In solid state,both 1 and 2 exhibit orange-red photoluminescence under ambient conditions.The photophysical and electrochemical measurements along with density functional theory(DFT)calculations reveal that the low-energy emissions can be attributed to singlet excited states with ligand-to-ligand charge-transfer(LLCT)character.This work suggests that strong-field N-heterocyclic carbene ligands play a crucial role to achieve the luminescence of Ni(II)complexes.展开更多
Chiral C2-symmetric N-heterocyclic carbene (NHC) palladium diaquo complex 5b prepared from (S)-BINAM was found to be a fairly effective catalyst for the enantioselective asymmetric fluorination of oxindoles to giv...Chiral C2-symmetric N-heterocyclic carbene (NHC) palladium diaquo complex 5b prepared from (S)-BINAM was found to be a fairly effective catalyst for the enantioselective asymmetric fluorination of oxindoles to give the corresponding products in moderate enantioselectivities along with good to excellent yields.展开更多
The oxygen-bridged dinuclear rare earth complexes(Ln=Nd(1),Y(2))bearing N-heterocyclic olefin moieties were synthesized by treating the imidazolidinium salt[SIMes-H]Br with potassium amide and rare earth bis(trimethyl...The oxygen-bridged dinuclear rare earth complexes(Ln=Nd(1),Y(2))bearing N-heterocyclic olefin moieties were synthesized by treating the imidazolidinium salt[SIMes-H]Br with potassium amide and rare earth bis(trimethylsilyl)amides.Complex 1 was characterized by X-ray diffraction analysis and complex 2 was characterized by 1H NMR spectroscopy.Both complexes were characterized by elemental analysis.Crystal data of complex 1:C74H138O2N8Si8Nd2,Mr=1685.12,orthorhombic,space group Pbca,a=25.1105(7),b=11.9188(2),c=29.6151(7)?,V=8863.4(4)?^3,Z=4,Dc=1.263 g·cm^-3,μ=1.311 mm^-1,F(000)=3544,the final R=0.0418 and wR=0.0770 for all data.The ring-opening of tetrahydrofuran molecule was proven,the possible mechanism for the formation of N-heterocyclic olefin(NHO)-rare earth complexes was speculated and the electronic and steric properties of SIMes and rare earth amides were discussed.This work provides a better understanding of N-heterocyclic carbene rare earth chemistry.展开更多
While N-alkenoxypyridinium salts are widely used for the synthesis ofα-functionalized ketones via umpolung strategy,such approaches are usually limited to special nucleophiles at high temperatures.Herein,we developed...While N-alkenoxypyridinium salts are widely used for the synthesis ofα-functionalized ketones via umpolung strategy,such approaches are usually limited to special nucleophiles at high temperatures.Herein,we developed an alternative photoinduced N-heterocyclic carbene(NHC)-mediated functionalization of N-alkenoxypyridinium salts with various nucleophiles,including tetramethylammonium azide,secondary amines,aryl and alkyl thiols,and even the challenging C(sp^(3))-nucleophiles,under mild conditions.A cascade radical-radical coupling/nucleophilic substitution sequence was proposed,wherein the NHC enabled the formation of a photoactive electron donor-acceptor complex forα-iodo ketone synthesis.展开更多
The complex (Ind)NiBr(1,3-bisbenzylimidazol-2-ylidene) (Ind = indenyl) 1 has been prepared in ca. 65% yield via the reaction of (Ind)2Ni with an equivalent of 1,3-bis-benzylimidazolium bromide in THF/CH2Cl2 at...The complex (Ind)NiBr(1,3-bisbenzylimidazol-2-ylidene) (Ind = indenyl) 1 has been prepared in ca. 65% yield via the reaction of (Ind)2Ni with an equivalent of 1,3-bis-benzylimidazolium bromide in THF/CH2Cl2 at 45℃, supported by elemental analysis, NMR spectroscopy and X-ray crystal determination. The crystal belongs to the triclinic system, space group Pi with a = 7.072(1), b = 11.264(2), c = 14.541(3)°A, α = 102.21(3),β = 93.44(3),γ = 90.81(3)°, V = 1129.7(4)°A^3, Z = 2, Mr = 502.08, Dc = 1.476 g/cm^3, F(000) = 512, μ= 2.642 mm^-1, R = 0.0490 and wR = 0.1137 for 3913 observed reflections (I〉 2σ(I)). The center nickel atom is coordinated by a bromide ligand, a carbene carbon and three carbon atoms of the five-membered indenyl group to form either a highly distorted square pyramid or a highly distorted square plane.展开更多
Ligands play a key role in controlling activity of organometallic complexes so that development of new ligands to overcome the challenge is the main topic of modern chemistry.The first example of 1,1-hydride migratory...Ligands play a key role in controlling activity of organometallic complexes so that development of new ligands to overcome the challenge is the main topic of modern chemistry.The first example of 1,1-hydride migratory insertion and intramolecular redox reaction has been realized in this work by applying a new ligand in rare-earth metal chemistry.The novel rare-earth metal complexes L^(Mes)RECH2TMS(THF)(RE=Y(1a),Dy(1b),Er(1c),Yb(1d),L^(Mes)=1-(3-(2,6-iPr_(2)C_(6)H_(3)N=CH)C8H4N)-CH_(2)CH_(2)-3-(2-CH2–4,6-Me_(2)C_(6)H_(2))-(N(CH)_(2)NC),THF=tetrahydrofuran)bearing a ligand with imino,indolyl,NHC(N-heterocyclic carbene)multiple functionalities were synthesized and characterized.Treatment of complexes 1 with silanes(PhSiH3or PhSiH2Me or PhSiD3)selectively produced the unprecedented 1,1-hydride(or deuterated H)migratory insertion of the indolyl moiety of the novel unsymmetrical dinuclear rare-earth metal complexes 2.The complex 2a reacts with Ph_(2)C=O to give the selective C=O double bond insertion to the RE–Co-methylene-Mesbond product 3a which further reacts with another Ph_(2)C=O(or DMAP,4-N,N-dimethylaminopyridine)affording the novelμ-η^(2):η^(3)-dianionic 3-iminoindolyl dinuclear rare-earth metal complex 4a.The latter is formed through an unusual intramolecular redox reaction(through electron migration from the 2-carbanion of the indolyl ring to the imino motif)resulting in the re-aromatization of the indolyl ring.展开更多
Poly-NHC-based organometallic assemblies 3-PF_(6),3-SbF_(6) and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spectrometry and single-crystal X-ray diffraction analyses.Controllable structural intercon...Poly-NHC-based organometallic assemblies 3-PF_(6),3-SbF_(6) and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spectrometry and single-crystal X-ray diffraction analyses.Controllable structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration,solvent and metal ion.1H NMR spectra of assembly 3-PF_(6) in CD_(3)CN at different concentrations demonstrated controllable structural interconversion,and ^(19)F NMR spectrum of assembly 3-PF_(6) at high concentration further evidenced the presence of the free hexafluorophosphate anion and encapsulated hexafluorophosphate anion for its two sets of signals.In addition,single-crystal X-ray diffraction analysis provided clear evidence that in the solid state,two assemblies 3-PF_(6) were vertically stuck,forming a self-aggregated dimer with an encapsulated hexafluorophosphate anion.Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.展开更多
基金Financial support from the National Natural Science Foundation of China(No.22101133)the Natural Science Foundation of Jiangsu Province(No.BK20200768)is greatly acknowledged.
文摘Palladacycles remain a challenging and significant research field in organic chemistry and have emerged as a type of powerful and versatile precatalysts or key active intermediates for transition metal catalysis.These achievements in this area are correlated to the design and development of useful ancillary ligands,such as N-heterocyclic carbenes(NHCs),which not only stabilize the actual catalytic active species facilitating the transformations,but also provide additional control over the selectivity of reactions.In this context,NHCs-ligated palladacycles(NHCP_(dcycles))with different electronic and steric properties have been synthesized and applied as green precatalysts(high stability and activity,low catalyst loading and mild reaction conditions)to accelerate transition metalcatalyzed reactions.Therefore,this review focuses mainly on the strategy of NHC-Pd_(cycles) design and catalytic results obtained from representative transition metal catalysis,such as Suzuki-Miyaura,Heck-Mizoroki and Sonogashira cross-coupling reactions,Buchwald-Hartwig amination,carbonylation as well as arylation.At last,the current limitations and potential trends for further development of NHC-Pdcycles are also highlighted.
基金financial support from the National Natural Science Foundation of China(22061041)Key Project of Science&Technology of Shaanxi Province(2023-YBGY-430)+5 种基金Project of Science&Technology Bureau of Yulin City(CXY-2022-185)Doctoral Research Foundation of Yan'an University(YDBK2019-60)the Training Program of Innovation and Entrepreneurship for Undergraduates of Yan'an University(D2022077)Research Program of Yan'an University(YDY2020-61)the Youth Innovation Team Project of Shaanxi Provincial Education Department(No.23JP193)National Science Foundation of Shaanxi Province(S2023-JC-QN-0079).
文摘Herein,we present a method for the homogeneous hydrogenation of nitroarenes to produce anilines using low catalyst loading(1 mo%)of copper N-heterocyclic carbene complexes as the catalyst and ammonia borane as the source of hydrogen.A wide range of nitroarenes,featuring diverse functional groups,were selectively transformed into their corresponding primary aromatic amines with high yields.This process can be readily scaled up and exhibits compatibility with various sensitive functional groups,including halogen,trifluoromethyl,aminomethyl,alkenyl,cyano,ester,amide,and hydroxyl.Notably,this catalytic methodology finds application in the synthesis of essential drug compounds.Mechanistic investigations suggest that the in-situ-generated Cu-H species may serve as active intermediates,with reduction pathways involving species such as azobenzene,1,2-diphenylhydrazine,nitrosobenzene,and N-phenylhydroxylamine.
基金financially supported by the National Natural Science Foundation of China (Nos.21774006 and 21634002)。
文摘The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with VOCl_(3).The total isolated yield of VOCl_(3)[1,3-(2,4,6-Me_(3)C_(6)H_(2))_(2)(NCH=)_(2)C:](V4') reached 86% by transmetallation reaction,which is much higher than that(48%) by direct coordination method.This methodology has also been used to synthesize the novel vanadium complexes containing unsymmetrical NHC ligands of VOCl_(3)[PhCH_(2)NCH=CHNR)C:](V5',R=2,4,6-Me_(3)C_(6)H_(2);V6',R=2,4-Me_(2)-6-Ph-C_(6)H_(2);V7',R=2,6-^(i)Pr_(2)-C_(6)H_(3)) with high yield,which could not be obtained by direct coordination method.The catalytic activity and copolymerization ability would be improved by introducing unsymmetrical NHC ligands due to their less steric bulky effect.The vanadium complex V5' containing unsymmetrical NHC ligand exhibits higher catalytic activity(3.7×10^(5)g_(copolymer)·mol^(-1) of V·h^(-1)) than that of V4' containing symmetrical NHC ligand.Moreover,the higher propylene incorporation ratio(45.6 mol%) in the copolymers of ethylene with propylene could be obtained by using V5' than that(39.9%) by using V4'.The results would provide a highly efficient strategy for the synthesis of early transition metal complexes containing versitile NHC ligands,affording the catalyst with both high catalytic activity and copolymerization ability for the synthesis of high performance polyolefin elastomers.
基金supported by the JSPS KAKENSHI (18K05265)JST Matching Planner Program (VP29117941122)+1 种基金JICA Collaboration Kick-starter Program (RU and IITH)the Cooperative Research Program of the Network Joint Research Center for Materials and Devices (Tokyo Institute of Technology)
文摘Thermally stable, solid-state luminescent organic materials are highly desired for the development of practical applications.Herein we synthesized new gold(I) complexes with N-heterocyclic carbene ligands, which have the ability to form strong metalorganic bond. Consequently, their thermochemical stability is enhanced at temperatures around 300 °C. Precise design of the molecular structure of the ligands, with a focus on ensuring low steric hindrance around Au atoms in order to limit disturbances to Au/Au interactions, provided a complex with a densely packed crystal with a shorter intermolecular Au–Au distance(3.17 ?)than the typical distance. In the solid state, this complex exhibited strong aurophilic interactions, which generated intense phosphorescence even in air at room temperature(quantum yield=16%) in spite of absence of any phosphorescence in solution.This behavior is characteristic for solid-state luminescence referred to as aggregation-controlled emission. Furthermore, the gold(I) complex displays capacity for mechano-and vapo-chromism—that is, the ability to change color reversibly in response to the application of external stimuli. We believe that the proposed design framework, which involves controlling thermal stability and luminescence property separately, provides a new opportunity for the development of practical applications using solid-state luminescent organic molecules.
文摘Three cobalt complexes bearing tunable,redox-active bipyridyl N-heterocyclic carbene(NHC)-based ligands have been studied for electrocatalytic hydrogen evolution from aqueous solutions.The effect of structural modifications to the ligand framework is investigated across the catalyst series,which includes a non-macrocyclic derivative(1-Co)and 16-(2-Co)and 15-(3-Co)membered macrocycles.A structure-activity relationship is demonstrated,in which the macrocyclic complexes have greater activity compared to their non-macrocyclic counterpart with the most rigid catalyst,supported by the 15-membered macrocycle,performing best overall.Indeed,3-Co catalyzes H2 evolution from aqueous pH 4 acetate buffer with a Faradaic efficiency of 97%at a low overpotential of 330 mV.Mechanistic studies are consistent with formation of a cobalt-hydride species that is subsequently protonated to evolve H2 via a heterolytic pathway.
基金the Natural Science Foundation of China(No.22175191)Y.C.thanks the financial support from CAS-Croucher Funding Scheme for Joint Laboratories and Beijing Municipal Science&Technology Commission(No.Z211100007921020).
文摘While nickel(II)complexes have been widely used as catalysts for carbon-carbon coupling reactions,the exploration of their photophysical and photochemical properties is still in the infancy.Here,a series of square-planar Ni(II)complexes[(diNHC)NiX2]bearing chelating benzimidazole-based bis(N-heterocyclic carbene)ligands and varying anionic coligands(1,X=Cl;2,X=Br;3,X=I)are synthesized and structurally characterized.In solid state,both 1 and 2 exhibit orange-red photoluminescence under ambient conditions.The photophysical and electrochemical measurements along with density functional theory(DFT)calculations reveal that the low-energy emissions can be attributed to singlet excited states with ligand-to-ligand charge-transfer(LLCT)character.This work suggests that strong-field N-heterocyclic carbene ligands play a crucial role to achieve the luminescence of Ni(II)complexes.
文摘Chiral C2-symmetric N-heterocyclic carbene (NHC) palladium diaquo complex 5b prepared from (S)-BINAM was found to be a fairly effective catalyst for the enantioselective asymmetric fluorination of oxindoles to give the corresponding products in moderate enantioselectivities along with good to excellent yields.
文摘The oxygen-bridged dinuclear rare earth complexes(Ln=Nd(1),Y(2))bearing N-heterocyclic olefin moieties were synthesized by treating the imidazolidinium salt[SIMes-H]Br with potassium amide and rare earth bis(trimethylsilyl)amides.Complex 1 was characterized by X-ray diffraction analysis and complex 2 was characterized by 1H NMR spectroscopy.Both complexes were characterized by elemental analysis.Crystal data of complex 1:C74H138O2N8Si8Nd2,Mr=1685.12,orthorhombic,space group Pbca,a=25.1105(7),b=11.9188(2),c=29.6151(7)?,V=8863.4(4)?^3,Z=4,Dc=1.263 g·cm^-3,μ=1.311 mm^-1,F(000)=3544,the final R=0.0418 and wR=0.0770 for all data.The ring-opening of tetrahydrofuran molecule was proven,the possible mechanism for the formation of N-heterocyclic olefin(NHO)-rare earth complexes was speculated and the electronic and steric properties of SIMes and rare earth amides were discussed.This work provides a better understanding of N-heterocyclic carbene rare earth chemistry.
基金financial support from the National Natural Science Foundation of China (No. 22001248)the Fundamental Research Funds for the Central Universities and the University of the Chinese Academy of Sciences
文摘While N-alkenoxypyridinium salts are widely used for the synthesis ofα-functionalized ketones via umpolung strategy,such approaches are usually limited to special nucleophiles at high temperatures.Herein,we developed an alternative photoinduced N-heterocyclic carbene(NHC)-mediated functionalization of N-alkenoxypyridinium salts with various nucleophiles,including tetramethylammonium azide,secondary amines,aryl and alkyl thiols,and even the challenging C(sp^(3))-nucleophiles,under mild conditions.A cascade radical-radical coupling/nucleophilic substitution sequence was proposed,wherein the NHC enabled the formation of a photoactive electron donor-acceptor complex forα-iodo ketone synthesis.
基金This work was supported by the National Natural Science Foundation of China (No. 20272040) and the Key Lab. of Organic Synthesis of Jiangsu Province
文摘The complex (Ind)NiBr(1,3-bisbenzylimidazol-2-ylidene) (Ind = indenyl) 1 has been prepared in ca. 65% yield via the reaction of (Ind)2Ni with an equivalent of 1,3-bis-benzylimidazolium bromide in THF/CH2Cl2 at 45℃, supported by elemental analysis, NMR spectroscopy and X-ray crystal determination. The crystal belongs to the triclinic system, space group Pi with a = 7.072(1), b = 11.264(2), c = 14.541(3)°A, α = 102.21(3),β = 93.44(3),γ = 90.81(3)°, V = 1129.7(4)°A^3, Z = 2, Mr = 502.08, Dc = 1.476 g/cm^3, F(000) = 512, μ= 2.642 mm^-1, R = 0.0490 and wR = 0.1137 for 3913 observed reflections (I〉 2σ(I)). The center nickel atom is coordinated by a bromide ligand, a carbene carbon and three carbon atoms of the five-membered indenyl group to form either a highly distorted square pyramid or a highly distorted square plane.
基金supported by the National Natural Science Foundation of China(22031001,21871004,21861162009,22171004)the grants from the Education Department of Anhui Province(GXXT-2021-052)。
文摘Ligands play a key role in controlling activity of organometallic complexes so that development of new ligands to overcome the challenge is the main topic of modern chemistry.The first example of 1,1-hydride migratory insertion and intramolecular redox reaction has been realized in this work by applying a new ligand in rare-earth metal chemistry.The novel rare-earth metal complexes L^(Mes)RECH2TMS(THF)(RE=Y(1a),Dy(1b),Er(1c),Yb(1d),L^(Mes)=1-(3-(2,6-iPr_(2)C_(6)H_(3)N=CH)C8H4N)-CH_(2)CH_(2)-3-(2-CH2–4,6-Me_(2)C_(6)H_(2))-(N(CH)_(2)NC),THF=tetrahydrofuran)bearing a ligand with imino,indolyl,NHC(N-heterocyclic carbene)multiple functionalities were synthesized and characterized.Treatment of complexes 1 with silanes(PhSiH3or PhSiH2Me or PhSiD3)selectively produced the unprecedented 1,1-hydride(or deuterated H)migratory insertion of the indolyl moiety of the novel unsymmetrical dinuclear rare-earth metal complexes 2.The complex 2a reacts with Ph_(2)C=O to give the selective C=O double bond insertion to the RE–Co-methylene-Mesbond product 3a which further reacts with another Ph_(2)C=O(or DMAP,4-N,N-dimethylaminopyridine)affording the novelμ-η^(2):η^(3)-dianionic 3-iminoindolyl dinuclear rare-earth metal complex 4a.The latter is formed through an unusual intramolecular redox reaction(through electron migration from the 2-carbanion of the indolyl ring to the imino motif)resulting in the re-aromatization of the indolyl ring.
基金supported by the National Natural Science Fund for Distinguished Young Scholars of China(No.22025107)Shaanxi Fundamental Science Research Project for Chemistry&Biology(No.22JHZ003)。
文摘Poly-NHC-based organometallic assemblies 3-PF_(6),3-SbF_(6) and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spectrometry and single-crystal X-ray diffraction analyses.Controllable structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration,solvent and metal ion.1H NMR spectra of assembly 3-PF_(6) in CD_(3)CN at different concentrations demonstrated controllable structural interconversion,and ^(19)F NMR spectrum of assembly 3-PF_(6) at high concentration further evidenced the presence of the free hexafluorophosphate anion and encapsulated hexafluorophosphate anion for its two sets of signals.In addition,single-crystal X-ray diffraction analysis provided clear evidence that in the solid state,two assemblies 3-PF_(6) were vertically stuck,forming a self-aggregated dimer with an encapsulated hexafluorophosphate anion.Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.