New mechanistic insight into the coupling reactions of CO2 and epoxides in the presence of zinc complexes

Hoon Sik Kim, Jai Jun Kim, Sang Deuk Lee, Myoung Soo Lah, Dohyun Moon, Ho Gyeom Jang

Research output: Contribution to journalArticle

88 Citations (Scopus)

Abstract

Coupling reactions of CO2 and epoxide to produce cyclic carbonates were performed in the presence of a catalyst [L2ZnX2] (L = pyridine or substituted pyridine; X = Cl, Br, I), and the effects of pyridine and halide ligands on the catalytic activity were investigated. The catalysts with electron-donating substituents on pyridine ligands exhibit higher activity than those with unsubstituted pyridine ligands. On the other hand, the catalysts with electron-with-drawing substituents at the 2-position of the pyridine ligands show no activity; this demonstrates the importance of the basicity of the pyridine ligands. The catalytic activity of [L2ZnX2] was found to decrease with increasing electronegativity of the halide ligands. A series of highly active zinc complexes bridged by pyridinium alkoxy ions of the general formula [{(μ-OCHRCH2L)ZnBr2}] (n = 2 for R = CH3; n = 3 for R = H; L = pyridine or substituted pyridine) were synthesized and characterized by X-ray crystallography. The dinuclear zinc complexes obtained from propylene oxide adopt a square-planar geometry for the Zn2O2 core with two bridging pyridinium propoxy ion ligands. Trinuclear zinc complexes prepared from ethylene oxide adopt a boat geometry for the Zn3O2 core, in which three zinc and three oxygen atoms are arranged in an alternate fashion. These zinc complexes bridged by pyridinium alkoxy ions were also isolated from the coupling reactions of CO2 and epoxides performed in the presence of [L2ZnBr2]. Rapid CO2 insertion into the zinc-oxygen bond of the zinc complexes bridged by pyridinium alkoxy ions leads to the formation of zinc carbonate species; these which yield cyclic carbonates and zinc complexes bridged by pyridinium alkoxy ions upon interaction with epoxides. The mechanistic pathways for the formation of active species and cyclic carbonates are discussed on the basis of results from structural and spectroscopic analyses.

Original languageEnglish
Pages (from-to)678-686
Number of pages9
JournalChemistry - A European Journal
Volume9
Issue number3
DOIs
Publication statusPublished - 2003 Feb 3

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Epoxy Compounds
Zinc
Ligands
Ions
Carbonates
Catalysts
Catalyst activity
Electrons
Oxygen
pyridine
Ethylene Oxide
Electronegativity
Geometry
Ships
X ray crystallography
X Ray Crystallography
Boats
Alkalinity
Atoms
alkoxyl radical

Keywords

  • Alkylene carbonate
  • Carbon dioxide fixation
  • Epoxides
  • Green chemistry
  • Homogeneous catalysis

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

New mechanistic insight into the coupling reactions of CO2 and epoxides in the presence of zinc complexes. / Kim, Hoon Sik; Kim, Jai Jun; Lee, Sang Deuk; Lah, Myoung Soo; Moon, Dohyun; Jang, Ho Gyeom.

In: Chemistry - A European Journal, Vol. 9, No. 3, 03.02.2003, p. 678-686.

Research output: Contribution to journalArticle

Kim, Hoon Sik ; Kim, Jai Jun ; Lee, Sang Deuk ; Lah, Myoung Soo ; Moon, Dohyun ; Jang, Ho Gyeom. / New mechanistic insight into the coupling reactions of CO2 and epoxides in the presence of zinc complexes. In: Chemistry - A European Journal. 2003 ; Vol. 9, No. 3. pp. 678-686.
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abstract = "Coupling reactions of CO2 and epoxide to produce cyclic carbonates were performed in the presence of a catalyst [L2ZnX2] (L = pyridine or substituted pyridine; X = Cl, Br, I), and the effects of pyridine and halide ligands on the catalytic activity were investigated. The catalysts with electron-donating substituents on pyridine ligands exhibit higher activity than those with unsubstituted pyridine ligands. On the other hand, the catalysts with electron-with-drawing substituents at the 2-position of the pyridine ligands show no activity; this demonstrates the importance of the basicity of the pyridine ligands. The catalytic activity of [L2ZnX2] was found to decrease with increasing electronegativity of the halide ligands. A series of highly active zinc complexes bridged by pyridinium alkoxy ions of the general formula [{(μ-OCHRCH2L)ZnBr2}] (n = 2 for R = CH3; n = 3 for R = H; L = pyridine or substituted pyridine) were synthesized and characterized by X-ray crystallography. The dinuclear zinc complexes obtained from propylene oxide adopt a square-planar geometry for the Zn2O2 core with two bridging pyridinium propoxy ion ligands. Trinuclear zinc complexes prepared from ethylene oxide adopt a boat geometry for the Zn3O2 core, in which three zinc and three oxygen atoms are arranged in an alternate fashion. These zinc complexes bridged by pyridinium alkoxy ions were also isolated from the coupling reactions of CO2 and epoxides performed in the presence of [L2ZnBr2]. Rapid CO2 insertion into the zinc-oxygen bond of the zinc complexes bridged by pyridinium alkoxy ions leads to the formation of zinc carbonate species; these which yield cyclic carbonates and zinc complexes bridged by pyridinium alkoxy ions upon interaction with epoxides. The mechanistic pathways for the formation of active species and cyclic carbonates are discussed on the basis of results from structural and spectroscopic analyses.",
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AU - Kim, Hoon Sik

AU - Kim, Jai Jun

AU - Lee, Sang Deuk

AU - Lah, Myoung Soo

AU - Moon, Dohyun

AU - Jang, Ho Gyeom

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N2 - Coupling reactions of CO2 and epoxide to produce cyclic carbonates were performed in the presence of a catalyst [L2ZnX2] (L = pyridine or substituted pyridine; X = Cl, Br, I), and the effects of pyridine and halide ligands on the catalytic activity were investigated. The catalysts with electron-donating substituents on pyridine ligands exhibit higher activity than those with unsubstituted pyridine ligands. On the other hand, the catalysts with electron-with-drawing substituents at the 2-position of the pyridine ligands show no activity; this demonstrates the importance of the basicity of the pyridine ligands. The catalytic activity of [L2ZnX2] was found to decrease with increasing electronegativity of the halide ligands. A series of highly active zinc complexes bridged by pyridinium alkoxy ions of the general formula [{(μ-OCHRCH2L)ZnBr2}] (n = 2 for R = CH3; n = 3 for R = H; L = pyridine or substituted pyridine) were synthesized and characterized by X-ray crystallography. The dinuclear zinc complexes obtained from propylene oxide adopt a square-planar geometry for the Zn2O2 core with two bridging pyridinium propoxy ion ligands. Trinuclear zinc complexes prepared from ethylene oxide adopt a boat geometry for the Zn3O2 core, in which three zinc and three oxygen atoms are arranged in an alternate fashion. These zinc complexes bridged by pyridinium alkoxy ions were also isolated from the coupling reactions of CO2 and epoxides performed in the presence of [L2ZnBr2]. Rapid CO2 insertion into the zinc-oxygen bond of the zinc complexes bridged by pyridinium alkoxy ions leads to the formation of zinc carbonate species; these which yield cyclic carbonates and zinc complexes bridged by pyridinium alkoxy ions upon interaction with epoxides. The mechanistic pathways for the formation of active species and cyclic carbonates are discussed on the basis of results from structural and spectroscopic analyses.

AB - Coupling reactions of CO2 and epoxide to produce cyclic carbonates were performed in the presence of a catalyst [L2ZnX2] (L = pyridine or substituted pyridine; X = Cl, Br, I), and the effects of pyridine and halide ligands on the catalytic activity were investigated. The catalysts with electron-donating substituents on pyridine ligands exhibit higher activity than those with unsubstituted pyridine ligands. On the other hand, the catalysts with electron-with-drawing substituents at the 2-position of the pyridine ligands show no activity; this demonstrates the importance of the basicity of the pyridine ligands. The catalytic activity of [L2ZnX2] was found to decrease with increasing electronegativity of the halide ligands. A series of highly active zinc complexes bridged by pyridinium alkoxy ions of the general formula [{(μ-OCHRCH2L)ZnBr2}] (n = 2 for R = CH3; n = 3 for R = H; L = pyridine or substituted pyridine) were synthesized and characterized by X-ray crystallography. The dinuclear zinc complexes obtained from propylene oxide adopt a square-planar geometry for the Zn2O2 core with two bridging pyridinium propoxy ion ligands. Trinuclear zinc complexes prepared from ethylene oxide adopt a boat geometry for the Zn3O2 core, in which three zinc and three oxygen atoms are arranged in an alternate fashion. These zinc complexes bridged by pyridinium alkoxy ions were also isolated from the coupling reactions of CO2 and epoxides performed in the presence of [L2ZnBr2]. Rapid CO2 insertion into the zinc-oxygen bond of the zinc complexes bridged by pyridinium alkoxy ions leads to the formation of zinc carbonate species; these which yield cyclic carbonates and zinc complexes bridged by pyridinium alkoxy ions upon interaction with epoxides. The mechanistic pathways for the formation of active species and cyclic carbonates are discussed on the basis of results from structural and spectroscopic analyses.

KW - Alkylene carbonate

KW - Carbon dioxide fixation

KW - Epoxides

KW - Green chemistry

KW - Homogeneous catalysis

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