Dinuclear Aluminum Complexes as Catalysts for Cycloaddition of CO2 to Epoxides

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• 作者：So Han Kim ; Duseong Ahn ; Min Jeong Go ; Myung Hwan Park ; Min Kim ; Junseong Lee ; Youngjo Kim
• 刊名：Organometallics
• 出版年：2014
• 出版时间：June 9, 2014
• 年：2014
• 卷：33
• 期：11
• 页码：2770-2775
• 全文大小：281K
• 年卷期：v.33,no.11(June 9, 2014)
• ISSN：1520-6041

文摘

The synthesis and characterization of dinuclear aluminum complexes bearing multidentate aliphatic aminoethanol-based ligands are presented. Single-crystal X-ray analyses, NMR data, and mass data reveal that four aluminum complexes synthesized are all dimeric in the solid, solution, and gas states. Especially, ²⁷Al NMR spectra have demonstrated that they exist as both five-coordinate Al(III) species in benzene-d₆ solution. All aluminum complexes are effective catalysts for the cycloaddition of CO₂ to propylene oxide in the presence of n-Bu₄NI as a cocatalyst. Complexes 1 and 3, which have two methyl groups per aluminum center, are better catalytic systems than the corresponding complexes 2 and 4 with a mono methyl group per aluminum. In addition, complexes 3 and 4 containing a pendant 鈭扖H₂CH₂NMe₂ group attached to nitrogen showed the higher activity than those 1 and 2 with a pendant 鈭扖H₂CH₂OMe group did. As expected, the catalytic activity for 3 increases as the reaction temperature increases up to 130 掳C. In addition, compound 3 showed the highest activity for the cycloaddition of CO₂ with propylene oxide in the presence of tetrabutylphosphonium bromide as a cocatalyst.