A series of substituted phenyl mono-imido complexes of the type W(NR)Cl_(4)(THF) (R=C_(6)H_(5),2,6-Me-C_(6)H_(3),3,5-Me-C_(6)H_(3),2,4,6-Me-C_(6)H_(2),4-OMe-C_(6)H_(4),2,6-F-C_(6)H_(3) and 3,5-CF_(3)-C_(6)H_(3)) have ...A series of substituted phenyl mono-imido complexes of the type W(NR)Cl_(4)(THF) (R=C_(6)H_(5),2,6-Me-C_(6)H_(3),3,5-Me-C_(6)H_(3),2,4,6-Me-C_(6)H_(2),4-OMe-C_(6)H_(4),2,6-F-C_(6)H_(3) and 3,5-CF_(3)-C_(6)H_(3)) have been synthesised and characterised. Reaction of these complexes with solid polymethylaluminoxane (sMAO) leads to immobilisation and in situ methylation of the chloride positions on the surface of the support. Reaction of W(NR)Cl_(4)(THF) with trimethylaluminium (TMA) yields the trimethyl complexes W(NR)Me3Cl. Immobilisation of the isotopically labelled W{N(2,6-F-C_(6)H_(3))}(^(13)CH_(3))_(3)Cl on sMAO furnished the supported complex with two identifiable methyl resonances in the ^(13)C–{^(1)H} solid state CPMAS spectrum (45 and 56 ppm),with the latter matching the unsupported complex,confirming retention of the structure on the surface. The sMAO-supported complexes (W:Al=1:150) were tested for their propensity to dimerise ethylene (1 bar) in d_(6)-benzene at 100℃ and compared with the previously reported sMAO-W{N(2,6-iPr-C_(6)H_(3))}Cl_(4)(THF) (sMAO-1.a). Complexes with electron deficient imido groups were shown to be the most active,and increased steric bulk in the ortho positions is also an important factor,with sMAO acting as a support,scavenger and activator. sMAO-W{N(3,5-CF_(3)-C_(6)H_(3))}Cl_(4)(THF) was the most active,demonstrating a turnover frequency of 5.65 mol_(C_(2)H_(4)) mol^(−1)_(W) h^(−1) and a selectivity towards 1-butene of 91% after 8 h.展开更多
Terminal rare-earth imido complexes containing metal-nitrogen double bonds have received more attention in recent years due to their importance in group transformation and catalytic reactions.However,due to the large ...Terminal rare-earth imido complexes containing metal-nitrogen double bonds have received more attention in recent years due to their importance in group transformation and catalytic reactions.However,due to the large difference in the orbital energy between rare-earth metals and nitrogen,their synthesis is difficult and the product is easy to polymerize.Here,we use the combination of Cp*and amidinate ligands to inhibit the tetramerization and provide exclusively the first anionic rare-earth(Ⅲ)terminal imido complexes with both electron-donating and electron-withdrawing groups.Chemical bond analysis further confirms the double-bond character,and the strong polarity of the REvN bond,which could be described as three orbital interactions,is primarily derived from the imido nitrogen,while the contribution from the rare-earth metal is limited.The mechanistic study using DFT calculations shows that the formation of the REvN bond involves the activation of two N-H bonds.Furthermore,the anionic rare-earth(Ⅲ)terminal imido complex shows some interesting and unique reactivity towards isocyanates,isonitriles,phenylsilanes,and W(CO)6.The work extends the multiple-bond chemistry between rare-earth metals and main group elements,and is expected to inspire the development of rare-earth organometallic chemistry and related fields.展开更多
The Lewis base-supported terminal uranium imido metallocene,[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U^(V)N(mesityl)(dmap)(2),is readily accessible from the reaction of[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)UMe_(2)(...The Lewis base-supported terminal uranium imido metallocene,[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U^(V)N(mesityl)(dmap)(2),is readily accessible from the reaction of[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)UMe_(2)(1)with mesitylNH_(2)in toluene in the presence of 4-dimethylaminopyridine(dmap).With compound 2 in hand,its reactivity towards small molecules was studied in detail.It reacts with terminal alkynes such as PhCuCH to form the amido alkynyl complex[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U[N(mesityl)CHvCHPh](CuCPh)(3)exclusively.In the reaction with thio-ketone Ph_(2)CS,CS_(2),isothiocyanate PhNCS and ketone Ph_(2)CO,the initial[2+2]cycloaddition intermediates are too labile to be isolated,yielding[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U(S_(2)CPh_(2))(dmap)(4)or dimeric sulfido and oxido complexes{[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U}_(2)(μ-E)_(2)(E=S(5),O(6)),respectively.Moreover,complex 2 may also behave as a nucleophile in the reaction with bis(catecholato)diboron(B_(2)cat_(2)),yielding the amido catecholate complex[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U[N(mesityl)B(BO_(2)C_(6)H_(4))O(C_(6)H_(4))O](8).In addition,the imido moiety of 2 may also engage in deprotonation reactions as demonstrated by its reactivity with the carboxamide PhCONH(p-tolyl)and organic nitrile PhCH_(2)CN,obtaining the uranium(IV)bis-amidate complex[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U[OC(Ph)N(p-tolyl)]_(2)(7)and the uranium(IV)iminato amido complex[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U[N(mesityl)vC(CH_(2)Ph)NH](NvCvCHPh)(9),respectively.Furthermore,2 may also participate in single-and two-electron transfer processes.It is singly oxidized by CuI,Ph_(2)S_(2),Ph_(2)Se_(2)and Ph_(3)CN_(3),yielding the uranium(V)imido complexes[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U^(V)N(mesityl)(X)(X=I(12),PhS(13),PhSe(14),and N_(3)(17)),or doubly oxidized by organic azides(RN_(3)),forming the uranium(VI)bis-imido metallocenes[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U^(V)N(mesityl)(vNR)(R=p-tolyl(15),mesityl(16)),respectively.Nevertheless,the addition of 1,2-diphenylhydrazine PhNHNHPh to complex 2 results in deprotonation and ligand elimination processes,yielding the uranium(V)bis-imido complex[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]U[vNPh]_(2)(dmap)_(3)(11)in the presence of dmap.展开更多
Surface Organometallic Chemistry(SOMC)aims at selective preparation of unusual or highly reactive species on the surfaces of inorganic supports in order to reach a better understanding of classical heterogeneous catal...Surface Organometallic Chemistry(SOMC)aims at selective preparation of unusual or highly reactive species on the surfaces of inorganic supports in order to reach a better understanding of classical heterogeneous catalysts and discover new reactivities and catalytic transformations.SOMC relies on the application of both surface science techniques and molecular organometallic chemistry;in particular it requires rational design of the molecular precursors to ensure their selective reactivity with the supports.In this report we apply the SOMC protocols to prepare well-defined silica-supported Zr imido complexes.展开更多
The scandium terminal imido complex supported by a monoanionic tetradentate NNNN ligand, [LSc=N(DIPP)](L = [MeC(N(DIPP))CHC(Me)(NCH2CH2N(Me)CH2CH2NMe2]-, DIPP = 2,6-(iPr)2C6H3)(1), undergoes a C–N bond cleavage at el...The scandium terminal imido complex supported by a monoanionic tetradentate NNNN ligand, [LSc=N(DIPP)](L = [MeC(N(DIPP))CHC(Me)(NCH2CH2N(Me)CH2CH2NMe2]-, DIPP = 2,6-(iPr)2C6H3)(1), undergoes a C–N bond cleavage at elevated temperature to give a mononuclear scandium anilido intermediate 2a, which subsequently aggregates into a binuclear scandium anilido complex 2. The mononuclear intermediate 2a reacts with alkyne or imine to provide two scandium anilido complexes 3 and 4, which contain a dianionic tetradentate NNNC ligand or a dianionic tetradentate NNNN ligand. DFT calculations on the reaction mechanism of C–N bond cleavage in 1 were also performed.展开更多
C-H amination by iron-imido/nitrene species has attracted increasing research interest in recent years because of its potential use in economical and environmentally benign syntheses of amino compounds.With the aim of...C-H amination by iron-imido/nitrene species has attracted increasing research interest in recent years because of its potential use in economical and environmentally benign syntheses of amino compounds.With the aim of providing a comprehensive overview of this field,which is of interest to both the synthetic organic and inorganic communities,this paper reviews the status quo of C-H amination chemistry by iron-imido/nitrene intermediates,as well as by well-defined iron-imido/nitrene compounds,with special emphasis on their structure/reactivity correlations.Achievements,problems,and perspectives in this growing field are discussed.展开更多
文摘A series of substituted phenyl mono-imido complexes of the type W(NR)Cl_(4)(THF) (R=C_(6)H_(5),2,6-Me-C_(6)H_(3),3,5-Me-C_(6)H_(3),2,4,6-Me-C_(6)H_(2),4-OMe-C_(6)H_(4),2,6-F-C_(6)H_(3) and 3,5-CF_(3)-C_(6)H_(3)) have been synthesised and characterised. Reaction of these complexes with solid polymethylaluminoxane (sMAO) leads to immobilisation and in situ methylation of the chloride positions on the surface of the support. Reaction of W(NR)Cl_(4)(THF) with trimethylaluminium (TMA) yields the trimethyl complexes W(NR)Me3Cl. Immobilisation of the isotopically labelled W{N(2,6-F-C_(6)H_(3))}(^(13)CH_(3))_(3)Cl on sMAO furnished the supported complex with two identifiable methyl resonances in the ^(13)C–{^(1)H} solid state CPMAS spectrum (45 and 56 ppm),with the latter matching the unsupported complex,confirming retention of the structure on the surface. The sMAO-supported complexes (W:Al=1:150) were tested for their propensity to dimerise ethylene (1 bar) in d_(6)-benzene at 100℃ and compared with the previously reported sMAO-W{N(2,6-iPr-C_(6)H_(3))}Cl_(4)(THF) (sMAO-1.a). Complexes with electron deficient imido groups were shown to be the most active,and increased steric bulk in the ortho positions is also an important factor,with sMAO acting as a support,scavenger and activator. sMAO-W{N(3,5-CF_(3)-C_(6)H_(3))}Cl_(4)(THF) was the most active,demonstrating a turnover frequency of 5.65 mol_(C_(2)H_(4)) mol^(−1)_(W) h^(−1) and a selectivity towards 1-butene of 91% after 8 h.
基金supported by the National Key R&D Program of China(no.2021YFF0701600)the National Natural Science Foundation of China(no.22371006 and 22131001)the Beijing National Laboratory for Molecular Sciences(BNLMS-CXXM-202401).
文摘Terminal rare-earth imido complexes containing metal-nitrogen double bonds have received more attention in recent years due to their importance in group transformation and catalytic reactions.However,due to the large difference in the orbital energy between rare-earth metals and nitrogen,their synthesis is difficult and the product is easy to polymerize.Here,we use the combination of Cp*and amidinate ligands to inhibit the tetramerization and provide exclusively the first anionic rare-earth(Ⅲ)terminal imido complexes with both electron-donating and electron-withdrawing groups.Chemical bond analysis further confirms the double-bond character,and the strong polarity of the REvN bond,which could be described as three orbital interactions,is primarily derived from the imido nitrogen,while the contribution from the rare-earth metal is limited.The mechanistic study using DFT calculations shows that the formation of the REvN bond involves the activation of two N-H bonds.Furthermore,the anionic rare-earth(Ⅲ)terminal imido complex shows some interesting and unique reactivity towards isocyanates,isonitriles,phenylsilanes,and W(CO)6.The work extends the multiple-bond chemistry between rare-earth metals and main group elements,and is expected to inspire the development of rare-earth organometallic chemistry and related fields.
基金National Natural Science Foundation of China(grant no.22271017)Deutsche Forschungsgemeinschaft(DFG)through the Heisenberg program(WA 2513/8)。
文摘The Lewis base-supported terminal uranium imido metallocene,[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U^(V)N(mesityl)(dmap)(2),is readily accessible from the reaction of[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)UMe_(2)(1)with mesitylNH_(2)in toluene in the presence of 4-dimethylaminopyridine(dmap).With compound 2 in hand,its reactivity towards small molecules was studied in detail.It reacts with terminal alkynes such as PhCuCH to form the amido alkynyl complex[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U[N(mesityl)CHvCHPh](CuCPh)(3)exclusively.In the reaction with thio-ketone Ph_(2)CS,CS_(2),isothiocyanate PhNCS and ketone Ph_(2)CO,the initial[2+2]cycloaddition intermediates are too labile to be isolated,yielding[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U(S_(2)CPh_(2))(dmap)(4)or dimeric sulfido and oxido complexes{[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U}_(2)(μ-E)_(2)(E=S(5),O(6)),respectively.Moreover,complex 2 may also behave as a nucleophile in the reaction with bis(catecholato)diboron(B_(2)cat_(2)),yielding the amido catecholate complex[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U[N(mesityl)B(BO_(2)C_(6)H_(4))O(C_(6)H_(4))O](8).In addition,the imido moiety of 2 may also engage in deprotonation reactions as demonstrated by its reactivity with the carboxamide PhCONH(p-tolyl)and organic nitrile PhCH_(2)CN,obtaining the uranium(IV)bis-amidate complex[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U[OC(Ph)N(p-tolyl)]_(2)(7)and the uranium(IV)iminato amido complex[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U[N(mesityl)vC(CH_(2)Ph)NH](NvCvCHPh)(9),respectively.Furthermore,2 may also participate in single-and two-electron transfer processes.It is singly oxidized by CuI,Ph_(2)S_(2),Ph_(2)Se_(2)and Ph_(3)CN_(3),yielding the uranium(V)imido complexes[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U^(V)N(mesityl)(X)(X=I(12),PhS(13),PhSe(14),and N_(3)(17)),or doubly oxidized by organic azides(RN_(3)),forming the uranium(VI)bis-imido metallocenes[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]_(2)U^(V)N(mesityl)(vNR)(R=p-tolyl(15),mesityl(16)),respectively.Nevertheless,the addition of 1,2-diphenylhydrazine PhNHNHPh to complex 2 results in deprotonation and ligand elimination processes,yielding the uranium(V)bis-imido complex[η^(5)-1,3-(Me_(3)Si)_(2)C_(5)H_(3)]U[vNPh]_(2)(dmap)_(3)(11)in the presence of dmap.
基金financially supported by the Russian Science Foundation(Grant No.19-73-10163)Elemental analyses and solution NMR measurements were performed using the equipment of the Center for Molecular Composition Studies of INEOS RAS supported by the Ministry of Science and Higher Education of the Russian Federation(Contract No.075-03-2023-642)P.Z.thanks Prof.C.Copéret and his group at ETH Zürich where DFT studies,solid-state NMR measurements and certain other experiments were performed.
文摘Surface Organometallic Chemistry(SOMC)aims at selective preparation of unusual or highly reactive species on the surfaces of inorganic supports in order to reach a better understanding of classical heterogeneous catalysts and discover new reactivities and catalytic transformations.SOMC relies on the application of both surface science techniques and molecular organometallic chemistry;in particular it requires rational design of the molecular precursors to ensure their selective reactivity with the supports.In this report we apply the SOMC protocols to prepare well-defined silica-supported Zr imido complexes.
基金This work was supported by the National Natural Science Foundation of China(21325210,21132002,21121062)the State Key Basic Research&Development Program(2012CB821600)the CAS/SAFEA International Partnership Program for Creative Research Teams.
文摘The scandium terminal imido complex supported by a monoanionic tetradentate NNNN ligand, [LSc=N(DIPP)](L = [MeC(N(DIPP))CHC(Me)(NCH2CH2N(Me)CH2CH2NMe2]-, DIPP = 2,6-(iPr)2C6H3)(1), undergoes a C–N bond cleavage at elevated temperature to give a mononuclear scandium anilido intermediate 2a, which subsequently aggregates into a binuclear scandium anilido complex 2. The mononuclear intermediate 2a reacts with alkyne or imine to provide two scandium anilido complexes 3 and 4, which contain a dianionic tetradentate NNNC ligand or a dianionic tetradentate NNNN ligand. DFT calculations on the reaction mechanism of C–N bond cleavage in 1 were also performed.
基金supported by the National Basic Research Program of China(2011CB808705)the National Natural Science Foundation of China(21002114 and 20872168)
文摘C-H amination by iron-imido/nitrene species has attracted increasing research interest in recent years because of its potential use in economical and environmentally benign syntheses of amino compounds.With the aim of providing a comprehensive overview of this field,which is of interest to both the synthetic organic and inorganic communities,this paper reviews the status quo of C-H amination chemistry by iron-imido/nitrene intermediates,as well as by well-defined iron-imido/nitrene compounds,with special emphasis on their structure/reactivity correlations.Achievements,problems,and perspectives in this growing field are discussed.
