Comprehensive Summary Four heterometallic rare earth(Ⅲ)-cobalt(Ⅱ)complexes(rare earth=Y(1),Sm(2),Nd(3),La(4))stabilized by an o-phenylenediamine-bridged tris(phenolato)ligand(L)have been synthesized and characterize...Comprehensive Summary Four heterometallic rare earth(Ⅲ)-cobalt(Ⅱ)complexes(rare earth=Y(1),Sm(2),Nd(3),La(4))stabilized by an o-phenylenediamine-bridged tris(phenolato)ligand(L)have been synthesized and characterized.In these tetranuclear complexes,one polydentate L coordinates to one rare earth(Ⅲ)ion,and one cobalt(Ⅱ)ion,respectively,while two rare earth ions are bridged by four acetate groups.These complexes were applied in the copolymerization of cyclohexene oxide and CO_(2),which showed good activity(TON up to 440)and high poly(cyclohexene carbonate)selectivity(>99%).Kinetic studies determined the equation as rate=k[CHO]1[CO_(2)]0[initiator]1,which proves a first-order dependence on initiator concentrations and implies a synergistic mechanism with rare earth and cobalt ions cooperating in epoxide ring-opening and chain propagation.展开更多
Amine elimination of Ln[N(SiMe3)2]3(μ-Cl)Li(THF)3 with aminophenol H[ON]{H[ON]=2-(CH2 NC5 H10)-4,6-tBu2-C6 H3OH}in 1:2 molar ratio in THF gave the monometallic rare-earth metal amide complexes[ON]2 LnN(SiMe3)2(Ln=Yb(...Amine elimination of Ln[N(SiMe3)2]3(μ-Cl)Li(THF)3 with aminophenol H[ON]{H[ON]=2-(CH2 NC5 H10)-4,6-tBu2-C6 H3OH}in 1:2 molar ratio in THF gave the monometallic rare-earth metal amide complexes[ON]2 LnN(SiMe3)2(Ln=Yb(1),Y(2),Gd(3),Sm(4),Nd(5))in 57%-73%isolated yields.All these complexes were characterized by elemental analysis.The molecular structures of complexes 1-4 were determined by single crystal X-ray diffraction.These complexes are highly active for L-Iactide polymerization to give high molecular weight polymers with unimodal molecular weight distributions.In addition,these complexes can also initiate rac-lactide polymerization with high activity to afford heterotactic-rich polylactides.展开更多
A series of o-phenylenediamine bridged tris(phenolate)ligand-stabilized rare-earth metal complexes were synthesized and characterized.Lanthanum(complex 1),neodymium(complex 2^(tBu)),and yttrium(complex 3)complexes sta...A series of o-phenylenediamine bridged tris(phenolate)ligand-stabilized rare-earth metal complexes were synthesized and characterized.Lanthanum(complex 1),neodymium(complex 2^(tBu)),and yttrium(complex 3)complexes stabilized by ligand of buiky tert-butyl substituents are mononuclear,whereas neodymium complexes 2^(Me)and 2^(C1)bearing smaller methyl and chloro substituents are dinuclear,respectively.They were applied in the alternating copolymerization of CO_(2)and cyclohexene oxide.The addition of benzyl alcohol is beneficial to improving yields(up to 86%)and selectivity of poly(carbonate)(up to 99%).Stoichiometric reaction of benzyl alcohol with rare-earth metal complexes 1 and 2^(tBu)results in formation of complexes 4 and 5 as dinuclear complexes with benzyl alcohol coordination,which was confirmed via single crystal X-ray diffraction analysis,and nuclear magnetic resonance(NMR)spectroscopy(for 4).Complex 5 shows equally good activity and selectivity of that of complex 2^(tBu)and benzyl alcohol,consolidating that complex 5 is indeed generated during polymerization.The neodymium tris(phenolate)5 is one of the few examples of rare-earth metal complex as a single-component initiator for copolymerization of epoxide and CO_(2).Matrix-assisted laser desorption ionization-time of flight(MALDI-TOF)mass spectrometry analysis proves benzyloxy group as the chain end.^(1)H NMR monitoring suggests that the insertion of CO_(2)may be the first step in the growth of the polymer chain.展开更多
Sequential addition of L-lactide(LA) followed by ε-caprolactone(CL), and simultaneous addition of both monomers, afforded random LA/CL copolymers in the presence of lanthanide aryloxides under mild conditions. Transe...Sequential addition of L-lactide(LA) followed by ε-caprolactone(CL), and simultaneous addition of both monomers, afforded random LA/CL copolymers in the presence of lanthanide aryloxides under mild conditions. Transesterification was proved to play a predominant role in random copolymer formation. Moreover, treatment of poly(L-lactide) with ε-CL led to random copolymer formation, which provides a new strategy not only to prepare random LA/CL copolymers, but also to directly modify PLLA.展开更多
A series of bimetallic lanthanide bis(amido) complexes stabilized by bridged bis(guanidinate) ligands {[(Me3Si)2N]2Ln[(RN)2-CN(CH2)2]}2 [R=iPr, Ln=Sm(1), Yb(2), Y(3); R=cyclohexyl(Cy), Ln=Sm(4), and Yb(5)] were synthe...A series of bimetallic lanthanide bis(amido) complexes stabilized by bridged bis(guanidinate) ligands {[(Me3Si)2N]2Ln[(RN)2-CN(CH2)2]}2 [R=iPr, Ln=Sm(1), Yb(2), Y(3); R=cyclohexyl(Cy), Ln=Sm(4), and Yb(5)] were synthesized through the metathesis reactions of {Ln(μ-Cl)[N(Si Me3)2]2(THF)}2(Ln=Sm, Yb, Y) with lithium guanidinate {Li[(RN)2CN(CH2)2]}2(R=iPr, Cy), the latter of which was generated in situ by the reaction of carbodiimides with lithium amides. Complexes 1–5 were well characterized by elemental analyses, IR spectra, and(for Complex 3) NMR spectroscopy. The solid-state molecular structures of all of the complexes were determined by single-crystal X-ray analyses with the exception of Complex 3, which showed similar unsolvated centrosymmetric dinuclear structures. Each of the lanthanide centers is four-coordinated with two nitrogen atoms from a guanidinate ligand and two nitrogen atoms from two amido groups. The piperazidine rings adopt chair conformations in all cases. These organolanthanide complexes were found to be efficient catalysts for the hydrophosphonylation reaction of various aldehydes and unactivated ketones and to afford ?-hydroxyphosphonates in high yields under low catalyst loading(0.1 mol%) in a short reaction time.展开更多
The reactivities of benzoxazine functionalized amine bridged bis(phenol)s LnH_(2)(n=1—3)with rare earth metal complexes were explored,founding that both the aryl substituents of the ligand and the rare earth metals h...The reactivities of benzoxazine functionalized amine bridged bis(phenol)s LnH_(2)(n=1—3)with rare earth metal complexes were explored,founding that both the aryl substituents of the ligand and the rare earth metals have profound influences on reaction outcomes.展开更多
基金financial support from the National Natural Science Foundation of China(21871198)the Major Research Project of the Natural Science of the Jiangsu Higher Education Institutions(19KJA360005 and 19KJA320007),and PAPD.
文摘Comprehensive Summary Four heterometallic rare earth(Ⅲ)-cobalt(Ⅱ)complexes(rare earth=Y(1),Sm(2),Nd(3),La(4))stabilized by an o-phenylenediamine-bridged tris(phenolato)ligand(L)have been synthesized and characterized.In these tetranuclear complexes,one polydentate L coordinates to one rare earth(Ⅲ)ion,and one cobalt(Ⅱ)ion,respectively,while two rare earth ions are bridged by four acetate groups.These complexes were applied in the copolymerization of cyclohexene oxide and CO_(2),which showed good activity(TON up to 440)and high poly(cyclohexene carbonate)selectivity(>99%).Kinetic studies determined the equation as rate=k[CHO]1[CO_(2)]0[initiator]1,which proves a first-order dependence on initiator concentrations and implies a synergistic mechanism with rare earth and cobalt ions cooperating in epoxide ring-opening and chain propagation.
基金Project supported by the National Natural Science Foundation of China(21572205,21971130,21871198,21674070)the Natural Science Foundation of Zhejiang Province(LY19B040002)+2 种基金the State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciencesthe Natural Science Foundation of Ningbo Municipal(2019A610030,2019A610129)K.C.Wong Magna Fund in Ningbo University。
文摘Amine elimination of Ln[N(SiMe3)2]3(μ-Cl)Li(THF)3 with aminophenol H[ON]{H[ON]=2-(CH2 NC5 H10)-4,6-tBu2-C6 H3OH}in 1:2 molar ratio in THF gave the monometallic rare-earth metal amide complexes[ON]2 LnN(SiMe3)2(Ln=Yb(1),Y(2),Gd(3),Sm(4),Nd(5))in 57%-73%isolated yields.All these complexes were characterized by elemental analysis.The molecular structures of complexes 1-4 were determined by single crystal X-ray diffraction.These complexes are highly active for L-Iactide polymerization to give high molecular weight polymers with unimodal molecular weight distributions.In addition,these complexes can also initiate rac-lactide polymerization with high activity to afford heterotactic-rich polylactides.
基金Project supported by the National Natural Science Foundation of China(21871198)the Major Research Project of the Natural Science of the Jiangsu Higher Education Institutions(19KJA360005)the Open Research Fund of State Key Laboratory of Rare-Earth Resource Utilization(CIAC)and PAPD。
文摘A series of o-phenylenediamine bridged tris(phenolate)ligand-stabilized rare-earth metal complexes were synthesized and characterized.Lanthanum(complex 1),neodymium(complex 2^(tBu)),and yttrium(complex 3)complexes stabilized by ligand of buiky tert-butyl substituents are mononuclear,whereas neodymium complexes 2^(Me)and 2^(C1)bearing smaller methyl and chloro substituents are dinuclear,respectively.They were applied in the alternating copolymerization of CO_(2)and cyclohexene oxide.The addition of benzyl alcohol is beneficial to improving yields(up to 86%)and selectivity of poly(carbonate)(up to 99%).Stoichiometric reaction of benzyl alcohol with rare-earth metal complexes 1 and 2^(tBu)results in formation of complexes 4 and 5 as dinuclear complexes with benzyl alcohol coordination,which was confirmed via single crystal X-ray diffraction analysis,and nuclear magnetic resonance(NMR)spectroscopy(for 4).Complex 5 shows equally good activity and selectivity of that of complex 2^(tBu)and benzyl alcohol,consolidating that complex 5 is indeed generated during polymerization.The neodymium tris(phenolate)5 is one of the few examples of rare-earth metal complex as a single-component initiator for copolymerization of epoxide and CO_(2).Matrix-assisted laser desorption ionization-time of flight(MALDI-TOF)mass spectrometry analysis proves benzyloxy group as the chain end.^(1)H NMR monitoring suggests that the insertion of CO_(2)may be the first step in the growth of the polymer chain.
基金supported by the National Natural Science Foundation of China (21402138, 21674070)the Major Research Project of the Natural Science of the Jiangsu Higher Education Institutions (14KJA150007)+1 种基金the Project of Scientific and Technologic Infrastructure of Suzhou (SZS201708)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Sequential addition of L-lactide(LA) followed by ε-caprolactone(CL), and simultaneous addition of both monomers, afforded random LA/CL copolymers in the presence of lanthanide aryloxides under mild conditions. Transesterification was proved to play a predominant role in random copolymer formation. Moreover, treatment of poly(L-lactide) with ε-CL led to random copolymer formation, which provides a new strategy not only to prepare random LA/CL copolymers, but also to directly modify PLLA.
基金supported by the National Natural Science Foundation of China(21132002,21372172,21402138)the Major Research Project of the Natural Science Foundation of the Jiangsu Higher Education Institutions(14KJA150007)the Qing Lan Project
文摘A series of bimetallic lanthanide bis(amido) complexes stabilized by bridged bis(guanidinate) ligands {[(Me3Si)2N]2Ln[(RN)2-CN(CH2)2]}2 [R=iPr, Ln=Sm(1), Yb(2), Y(3); R=cyclohexyl(Cy), Ln=Sm(4), and Yb(5)] were synthesized through the metathesis reactions of {Ln(μ-Cl)[N(Si Me3)2]2(THF)}2(Ln=Sm, Yb, Y) with lithium guanidinate {Li[(RN)2CN(CH2)2]}2(R=iPr, Cy), the latter of which was generated in situ by the reaction of carbodiimides with lithium amides. Complexes 1–5 were well characterized by elemental analyses, IR spectra, and(for Complex 3) NMR spectroscopy. The solid-state molecular structures of all of the complexes were determined by single-crystal X-ray analyses with the exception of Complex 3, which showed similar unsolvated centrosymmetric dinuclear structures. Each of the lanthanide centers is four-coordinated with two nitrogen atoms from a guanidinate ligand and two nitrogen atoms from two amido groups. The piperazidine rings adopt chair conformations in all cases. These organolanthanide complexes were found to be efficient catalysts for the hydrophosphonylation reaction of various aldehydes and unactivated ketones and to afford ?-hydroxyphosphonates in high yields under low catalyst loading(0.1 mol%) in a short reaction time.
基金support fromtheNational Natural Science Foundation of China(21871198)the Major Research Project of the Natural Science of the Jiangsu Higher Education Institutions(19KJA360005),and PAPD.
文摘The reactivities of benzoxazine functionalized amine bridged bis(phenol)s LnH_(2)(n=1—3)with rare earth metal complexes were explored,founding that both the aryl substituents of the ligand and the rare earth metals have profound influences on reaction outcomes.