Single-Site -Diiminate Zinc Catalysts for the Alternating Copolymerization of CO2 and Epoxides: Catalyst S
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- 作者：Ming Cheng ; David R. Moore ; Joseph J. Reczek ; Bradley M. Chamberlain ; Emil B. Lobkovsky ; and Geoffrey W. Coates
- 刊名：Journal of the American Chemical Society
- 出版年：2001
- 出版时间：September 12, 2001
- 年：2001
- 卷：123
- 期：36
- 页码：8738 - 8749
- 全文大小：189K
- 年卷期：v.123,no.36(September 12, 2001)
- ISSN：1520-5126
文摘
Synthetic routes to zinc 
-diiminate complexes are reported. The synthesis of 11 -diimine [(BDI)-H] ligands, with varying N-aryl substituents and bridging structures, is described. These ligands are convertedto (BDI)ZnX complexes (X = OAc, Et, N(SiMe3)2, Br, Cl, OH, OMe, OiPr). X-ray structural data revealedthat all zinc complexes examined exist as 
-X-bridged dimers in the solid state, with the exception of the zincethyl and amido complexes which were monomeric. Complexes of the form (BDI)ZnOR (R = alkyl, acyl)and (BDI)ZnN(SiMe3)2 are highly active catalysts for the alternating copolymerization of epoxides and CO2.Copolymerizations of cyclohexene oxide (CHO) and CO2 with (BDI-1)ZnX [(BDI-1) = 2-((2,6-diisopropylphenyl)amido)-4-((2,6-diisopropylphenyl)imino)-2-pentene)] and (BDI-2)ZnX [(BDI-2) = 2-((2,6-diethylphenyl)amido)-4-((2,6-diethylphenyl)imino)-2-pentene)], where X = OAc, Et, N(SiMe3)2, Br, Cl, OH, OMe, OiPr,were attempted at 50 
C and 100 psi CO2. Complexes with X = OAc, N(SiMe3)2, OMe, OiPr all producedpolycarbonate by the alternated insertion of CHO and CO2 with similar catalytic activities, comparable molecularweights, and narrow molecular weight distributions (MWD ~ 1.1), indicating the copolymerizations are living.Furthermore, ligand effects were shown to dramatically influence the polymerization activity as minor stericchanges accelerated or terminated the polymerization activity.
-diiminate complexes are reported. The synthesis of 11 -diimine [(BDI)-H] ligands, with varying N-aryl substituents and bridging structures, is described. These ligands are convertedto (BDI)ZnX complexes (X = OAc, Et, N(SiMe3)2, Br, Cl, OH, OMe, OiPr). X-ray structural data revealedthat all zinc complexes examined exist as -X-bridged dimers in the solid state, with the exception of the zincethyl and amido complexes which were monomeric. Complexes of the form (BDI)ZnOR (R = alkyl, acyl)and (BDI)ZnN(SiMe3)2 are highly active catalysts for the alternating copolymerization of epoxides and CO2.Copolymerizations of cyclohexene oxide (CHO) and CO2 with (BDI-1)ZnX [(BDI-1) = 2-((2,6-diisopropylphenyl)amido)-4-((2,6-diisopropylphenyl)imino)-2-pentene)] and (BDI-2)ZnX [(BDI-2) = 2-((2,6-diethylphenyl)amido)-4-((2,6-diethylphenyl)imino)-2-pentene)], where X = OAc, Et, N(SiMe3)2, Br, Cl, OH, OMe, OiPr,were attempted at 50 C and 100 psi CO2. Complexes with X = OAc, N(SiMe3)2, OMe, OiPr all producedpolycarbonate by the alternated insertion of CHO and CO2 with similar catalytic activities, comparable molecularweights, and narrow molecular weight distributions (MWD ~ 1.1), indicating the copolymerizations are living.Furthermore, ligand effects were shown to dramatically influence the polymerization activity as minor stericchanges accelerated or terminated the polymerization activity.