- The ethylsulfinate ligand: A highly efficient initiating group for the zinc β-diiminate catalyzed copolymerization reaction of CO2 and epoxides
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The quantitative synthesis of a series of new zinc(II) sulfinate complexes (4a-e) by insertion of SO2 into zinc-ethyl bonds of β-diiminate complexes ((ArN=C(CH3)CH=(CH3)CNAr)Zn(O(S=O)Et); Ar = 2,6-diisopropylphenyl (4a), 2
- Eberhardt, Robert,Allmendinger, Markus,Luinstra, Gerrit A.,Rieger, Bernhard
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p. 211 - 214
(2008/10/08)
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- Single-site β-diiminate zinc catalysts for the alternating copolymerization of CO2 and epoxides: Catalyst synthesis and unprecedented polymerization activity
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Synthetic routes to zinc β-diiminate complexes are reported. The synthesis of 11 β-diimine [(BDI)-H] ligands, with varying N-aryl substituents and bridging structures, is described. These ligands are converted to (BDI)ZnX complexes (X = OAc, Et, N(SiMe3)2, Br, Cl, OH, OMe, OiPr). X-ray structural data revealed that all zinc complexes examined exist as μ-X-bridged dimers in the solid state, with the exception of the zinc ethyl 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 produced polycarbonate by the alternated insertion of CHO and CO2 with similar catalytic activities, comparable molecular weights, 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 steric changes accelerated or terminated the polymerization activity.
- Cheng,Moore,Reczek,Chamberlain,Lobkovsky,Coates
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p. 8738 - 8749
(2007/10/03)
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