Abstract
The facile synthesis, structural characterization, and catalytic studies for CO2/epoxide coupling of nickel acetates based on carbazolide-bis(NHC) (NHC = N-heterocyclic carbene) were reported. Treatment of 3,6-di-tert-butyl-1,8-bis(3-alkylimidazolium-1-yl)carbazole salt proligands (bis(R-Im-X)Cz, R = benzyl (Bn), n-butyl (nBu), methyl (Me), X = Br or I) with nickel acetate tetrahydrate in the presence of excess triethylamine generated monomeric four-coordinate nickel complexes [(bis(R-Im)Cz)Ni(OAc)] (R = Bn (3), R = nBu (4), and R = Me (5)). Single-crystal X-ray diffraction of Ni complexes 4 and 5 indicates that the bis(NHC)-carbazolide fragment behaves as a CNC-tridentate pincer ligand to coordinate the metal center, and the ancillary acetate group assumes a terminal acetate bonding mode. Catalysis for coupling of carbon dioxide with cyclohexene oxide (CHO) by these carbazolide-bis(NHC)-ligated Ni complexes was systematically examined. Experimental results displayed that cycloaddition of CHO and CO2 catalyzed with complex 4 could give cyclohexene carbonate (CHC) with >99% cis-isomer selectivity on using low catalyst concentrations and high reaction temperature, whereas catalyst 3 was able to copolymerize CHO and CO2 to afford a narrowly dispersed and perfectly alternating poly(cyclohexene carbonate) (PCHC) as the major product at the higher catalyst loadings and lower copolymerization temperature. This is the first time that the air-stable bis(NHC)-carbazolide nickel(II) acetate is an effective and versatile catalyst for the formation of either biodegradable PCHCs or cis-CHCs.
| Original language | English |
|---|---|
| Pages (from-to) | 291-297 |
| Number of pages | 7 |
| Journal | Organometallics |
| Volume | 36 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 2017 Jan 23 |
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All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry
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Nickel-Catalyzed Coupling of Carbon Dioxide with Cyclohexene Oxide by Well-Characterized Bis(N-Heterocyclic Carbene) Carbazolide Complexes. / Lee, Ting Yu; Lin, Yi Jen; Chang, Yuan Zhen; Huang, Li Shin; Ko, Bao Tsan; Huang, Jui Hsien.
In: Organometallics, Vol. 36, No. 2, 23.01.2017, p. 291-297.Research output: Contribution to journal › Article
TY - JOUR
T1 - Nickel-Catalyzed Coupling of Carbon Dioxide with Cyclohexene Oxide by Well-Characterized Bis(N-Heterocyclic Carbene) Carbazolide Complexes
AU - Lee, Ting Yu
AU - Lin, Yi Jen
AU - Chang, Yuan Zhen
AU - Huang, Li Shin
AU - Ko, Bao Tsan
AU - Huang, Jui Hsien
PY - 2017/1/23
Y1 - 2017/1/23
N2 - The facile synthesis, structural characterization, and catalytic studies for CO2/epoxide coupling of nickel acetates based on carbazolide-bis(NHC) (NHC = N-heterocyclic carbene) were reported. Treatment of 3,6-di-tert-butyl-1,8-bis(3-alkylimidazolium-1-yl)carbazole salt proligands (bis(R-Im-X)Cz, R = benzyl (Bn), n-butyl (nBu), methyl (Me), X = Br or I) with nickel acetate tetrahydrate in the presence of excess triethylamine generated monomeric four-coordinate nickel complexes [(bis(R-Im)Cz)Ni(OAc)] (R = Bn (3), R = nBu (4), and R = Me (5)). Single-crystal X-ray diffraction of Ni complexes 4 and 5 indicates that the bis(NHC)-carbazolide fragment behaves as a CNC-tridentate pincer ligand to coordinate the metal center, and the ancillary acetate group assumes a terminal acetate bonding mode. Catalysis for coupling of carbon dioxide with cyclohexene oxide (CHO) by these carbazolide-bis(NHC)-ligated Ni complexes was systematically examined. Experimental results displayed that cycloaddition of CHO and CO2 catalyzed with complex 4 could give cyclohexene carbonate (CHC) with >99% cis-isomer selectivity on using low catalyst concentrations and high reaction temperature, whereas catalyst 3 was able to copolymerize CHO and CO2 to afford a narrowly dispersed and perfectly alternating poly(cyclohexene carbonate) (PCHC) as the major product at the higher catalyst loadings and lower copolymerization temperature. This is the first time that the air-stable bis(NHC)-carbazolide nickel(II) acetate is an effective and versatile catalyst for the formation of either biodegradable PCHCs or cis-CHCs.
AB - The facile synthesis, structural characterization, and catalytic studies for CO2/epoxide coupling of nickel acetates based on carbazolide-bis(NHC) (NHC = N-heterocyclic carbene) were reported. Treatment of 3,6-di-tert-butyl-1,8-bis(3-alkylimidazolium-1-yl)carbazole salt proligands (bis(R-Im-X)Cz, R = benzyl (Bn), n-butyl (nBu), methyl (Me), X = Br or I) with nickel acetate tetrahydrate in the presence of excess triethylamine generated monomeric four-coordinate nickel complexes [(bis(R-Im)Cz)Ni(OAc)] (R = Bn (3), R = nBu (4), and R = Me (5)). Single-crystal X-ray diffraction of Ni complexes 4 and 5 indicates that the bis(NHC)-carbazolide fragment behaves as a CNC-tridentate pincer ligand to coordinate the metal center, and the ancillary acetate group assumes a terminal acetate bonding mode. Catalysis for coupling of carbon dioxide with cyclohexene oxide (CHO) by these carbazolide-bis(NHC)-ligated Ni complexes was systematically examined. Experimental results displayed that cycloaddition of CHO and CO2 catalyzed with complex 4 could give cyclohexene carbonate (CHC) with >99% cis-isomer selectivity on using low catalyst concentrations and high reaction temperature, whereas catalyst 3 was able to copolymerize CHO and CO2 to afford a narrowly dispersed and perfectly alternating poly(cyclohexene carbonate) (PCHC) as the major product at the higher catalyst loadings and lower copolymerization temperature. This is the first time that the air-stable bis(NHC)-carbazolide nickel(II) acetate is an effective and versatile catalyst for the formation of either biodegradable PCHCs or cis-CHCs.
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U2 - 10.1021/acs.organomet.6b00756
DO - 10.1021/acs.organomet.6b00756
M3 - Article
AN - SCOPUS:85018479774
VL - 36
SP - 291
EP - 297
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 2
ER -