We herein report on solution structural studies of Ru^Ⅱ catalysts （3a, 9） composed of achiral bisphosphine ligands （4, 8） and the enantiopure 1,2-diphenylethylenediamine （DPEN）. Complete chiral induction from e...We herein report on solution structural studies of Ru^Ⅱ catalysts （3a, 9） composed of achiral bisphosphine ligands （4, 8） and the enantiopure 1,2-diphenylethylenediamine （DPEN）. Complete chiral induction from enantiopure （R,R）-DPEN to achiral bisphosphine ligand 3a was observed in solution, with the complex adopting a single, stable and non-fluxional （even at 70 ℃） configuration. The coordination of the C=O moiety in 4 to the cationic Run center is considered to be of key importance in providing the higher thermodynamic and kinetic rotation barrier for the flexible bisphosphine ligand in the complex. The obtained enantioselectivity （91% enantiomeric excess） and sense of chiral induction in the hydrogenation of acetophenone were found to be solely dependent on the chirality of the 1,2-diamine. Consistent with the hydrogenation product, the （R,R）-DPEN induces a M-conformation （fight-handed） chirality for flexible phosphine ligand 4 in the complex, resulting in a 2,2-configuration about the Ru^Ⅱ center.展开更多
A series of new bisphosphine-monoxide(BPMO)ligands based on benzothiophene backbone and the corresponding palladium complexes{k2-P(O)(Ph)2-3-PR1R2-C8H4S}PdMeCl{2a:R1=R2=Ph;2b:R1=R2=2-0Me-Ph;2c:R1=R2=2-CF3-Ph;2d:Rl=Ph,...A series of new bisphosphine-monoxide(BPMO)ligands based on benzothiophene backbone and the corresponding palladium complexes{k2-P(O)(Ph)2-3-PR1R2-C8H4S}PdMeCl{2a:R1=R2=Ph;2b:R1=R2=2-0Me-Ph;2c:R1=R2=2-CF3-Ph;2d:Rl=Ph,R2=2-(2',6'-(OMe)2C6Hz)-C6H4}were synthesized and fully characterized by1H-,13C-,31P-,and 2D-NMR spectroscopy and single-crystal X-ray dfraction.In the presence of Na+B[3,5-(CF3)2C6H3]4(NaBArF),these complexes showed very high activities(up to 2.0 x 10’g-mol-1.h-)for ethylene polymerization.More significantly,these catalysts enabled the copolymerization of ethylene with a broad scope of commercially available polar comonomers such as acrylates,acrylic acid,acrylonitrile,vinyltrialkoxysilane,allyl acetate,and long-chain 6-chloro-1-hexene to give functionalized polyethylene with reasonable catalytic activities(up to 105 g-mol-l.h-)and incorporations(up to 5.3 mol96).This contribution suggests that,besides the modulation of conventionally steric and electronic factors,the connectivity(at dfferent linking positions)of BPMO(P,O)donors to the heteroaryl backbone also greatly infuences the catalyst properties in terms of catalytic activity,polymer branching content,comonomer scope,and comonomer incorporation.展开更多
We report the polymerization of phenyl isocyanides with the chiral palladium（II） initiating system. The resulting polymers with optically active properties were obtained by polymerization of the racemic isocyanide m...We report the polymerization of phenyl isocyanides with the chiral palladium（II） initiating system. The resulting polymers with optically active properties were obtained by polymerization of the racemic isocyanide monomer （rac-1）, and enantiomerically unbalanced polymerization of the monomer was found, providing substantial evidence for the enantiomer-selective polymerization of rac- 1 mediated through chiral catalyst. A comparison between the enantiomerically pure monomers, 4-isocyanobenzoyl-L-alanine decyl ester （1 s） and 4-isocyanobenzoyl-D-alanine decyl ester （1 r）, revealed a drastic discrepancy in the reactivity ratio of their homopolymerizations. It turned out that the monomer reactivity ratio of ls was higher than that of lr with chiral ligands. The results clearly demonstrated the inclination for incorporation of the ls enantiomer during the polymerization process and thus resulted in the enantiomer-selective polymerization in this system. The effects of the catalyst chirality on the optically active properties of polymerization were investigated, and it was concluded that the formation of higher-ordered conformation with a handed helicity might be attributed to the chiral induction of chiral palladium（II） catalyst. Moreover, the polymers obtained through the enantiomer-selective polymerization of the enantiomerically pure monomer were with a significant improvement of the optical activity if the chirality of the monomer and the catalyst matched with each other.展开更多
基金Project supported by the National Natural Science Foundation of China, Chinese Academy of Sciences, the Major Basic Research Development Program of China （No. 2006CB806106）, the Science and Technology Commission of Shanghai Municipality and Merck Research Laboratories.
文摘We herein report on solution structural studies of Ru^Ⅱ catalysts （3a, 9） composed of achiral bisphosphine ligands （4, 8） and the enantiopure 1,2-diphenylethylenediamine （DPEN）. Complete chiral induction from enantiopure （R,R）-DPEN to achiral bisphosphine ligand 3a was observed in solution, with the complex adopting a single, stable and non-fluxional （even at 70 ℃） configuration. The coordination of the C=O moiety in 4 to the cationic Run center is considered to be of key importance in providing the higher thermodynamic and kinetic rotation barrier for the flexible bisphosphine ligand in the complex. The obtained enantioselectivity （91% enantiomeric excess） and sense of chiral induction in the hydrogenation of acetophenone were found to be solely dependent on the chirality of the 1,2-diamine. Consistent with the hydrogenation product, the （R,R）-DPEN induces a M-conformation （fight-handed） chirality for flexible phosphine ligand 4 in the complex, resulting in a 2,2-configuration about the Ru^Ⅱ center.
基金the National Natural Science Foundation of China(No.21871250)the Jilin Provincial Science and Technology Department Program(No.20190201009JC)Shaanxi Provincial Natural Science Basic Research Program-Shaanxi Coal and Chemical Industry Group Co,Ltd.Joint Fund(No.2019JLZ-02).
文摘A series of new bisphosphine-monoxide(BPMO)ligands based on benzothiophene backbone and the corresponding palladium complexes{k2-P(O)(Ph)2-3-PR1R2-C8H4S}PdMeCl{2a:R1=R2=Ph;2b:R1=R2=2-0Me-Ph;2c:R1=R2=2-CF3-Ph;2d:Rl=Ph,R2=2-(2',6'-(OMe)2C6Hz)-C6H4}were synthesized and fully characterized by1H-,13C-,31P-,and 2D-NMR spectroscopy and single-crystal X-ray dfraction.In the presence of Na+B[3,5-(CF3)2C6H3]4(NaBArF),these complexes showed very high activities(up to 2.0 x 10’g-mol-1.h-)for ethylene polymerization.More significantly,these catalysts enabled the copolymerization of ethylene with a broad scope of commercially available polar comonomers such as acrylates,acrylic acid,acrylonitrile,vinyltrialkoxysilane,allyl acetate,and long-chain 6-chloro-1-hexene to give functionalized polyethylene with reasonable catalytic activities(up to 105 g-mol-l.h-)and incorporations(up to 5.3 mol96).This contribution suggests that,besides the modulation of conventionally steric and electronic factors,the connectivity(at dfferent linking positions)of BPMO(P,O)donors to the heteroaryl backbone also greatly infuences the catalyst properties in terms of catalytic activity,polymer branching content,comonomer scope,and comonomer incorporation.
基金financially supported by the National Natural Science Foundation of China (Nos. 51673057, 21622402, and 21574036)N. Liu thanks Anhui Provincial Natural Science Foundation (No. 1608085MB41)
文摘We report the polymerization of phenyl isocyanides with the chiral palladium（II） initiating system. The resulting polymers with optically active properties were obtained by polymerization of the racemic isocyanide monomer （rac-1）, and enantiomerically unbalanced polymerization of the monomer was found, providing substantial evidence for the enantiomer-selective polymerization of rac- 1 mediated through chiral catalyst. A comparison between the enantiomerically pure monomers, 4-isocyanobenzoyl-L-alanine decyl ester （1 s） and 4-isocyanobenzoyl-D-alanine decyl ester （1 r）, revealed a drastic discrepancy in the reactivity ratio of their homopolymerizations. It turned out that the monomer reactivity ratio of ls was higher than that of lr with chiral ligands. The results clearly demonstrated the inclination for incorporation of the ls enantiomer during the polymerization process and thus resulted in the enantiomer-selective polymerization in this system. The effects of the catalyst chirality on the optically active properties of polymerization were investigated, and it was concluded that the formation of higher-ordered conformation with a handed helicity might be attributed to the chiral induction of chiral palladium（II） catalyst. Moreover, the polymers obtained through the enantiomer-selective polymerization of the enantiomerically pure monomer were with a significant improvement of the optical activity if the chirality of the monomer and the catalyst matched with each other.
