Bimetallic anilido-aldimine zinc complexes for epoxide/CO2 copolymerization

Yeoul Lee Bun, Yong Kwon Heon, Yeon Lee Su, Jae Na Sung, Song I. Han, Hoseop Yun, Hyosun Lee, Young Whan Park

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74 Scopus citations

Abstract

Acyclic o-phenylene-bridged bis(anilido-aldimine) compounds, o-C 6H4{C6H2R2N=CH-C 6H4-(H)N(C6H3R′2)} 2 and related 30-membered macrocyclic compounds, o-C 6H4{C6H2R′2N= CH-C6H4-(H)N-C6H2R2} 2 (o-C6H4) are prepared. Successive additions of Me2Zn and SO2 gas to the bis(anilido-aldimine) compounds afford quantitatively dinuclear μ-methylsulfinato zinc complexes, o-C6H4{(C6H2R2N=CH-C 6H4-N(C6H3R′2)- κ2-N,N)Zn(μ-OS(O)Me)}2 (R = iPr and R′ = iPr, 29; R = Et and R′ = Et, 30; R = Me and R′ = Me, 31; R = Me and R′ = iPr, 32; R = Et and R′ = Me, 33; R = Et and R′ = iPr, 34; R = iPr and R′ = Et, 35) and o-C6H4{C 6H2R′2N=CH-C6H 4-N-C6H2R22-N,N) Zn(μ-OS(O)Me)}2 (o-C6H4) (R = Et and R′ = Et, 36; R = Me and R′ = Me, 37; R = iPr and R′ = Me, 38; R = Et and R′ = Me, 39; R = Me and R′ = iPr, 40). Molecular structures of 34 and 40 are confirmed by X-ray crystallography. Complexes 30-35 show high activity for cyclohexene oxide/CO2 copolymerization at low [Zn]/[monomer] ratio (1:5600), whereas the complex of mononucleating β-diketiminate {[(C6H3Et2)N=C(Me)CH=C(Me) N(C6H3Et2)]Zn(μ-OS(O)Et)}2 shows negligible activity in the same condition. Activity is sensitive to the N-aryl ortho substituents and the highest activity is observed with 32. Turnover number up to 2980 and molecular weight (Mn) up to 284 000 are attained with 32 at such a highly diluted condition as [Zn]/[monomer] = 1:17 400. Macrocyclic complexes 36-40 show negligible activity for copolymerization.

Original languageEnglish
Pages (from-to)3031-3037
Number of pages7
JournalJournal of the American Chemical Society
Volume127
Issue number9
DOIs
StatePublished - 9 Mar 2005

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