Chromium complexes with tridentate NN鈥睴 Schiff base ligands as catalysts for the coupling of CO₂ and epoxides

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• 作者：Siham Iksi ; Ali Aghmiz ; Raquel Rivas ; M. Dolores Gonz谩lez ; Laia Cuesta-Aluja ; Javier Castilla ; Arantxa Orej贸n ; Farid El Guemmout ; Anna M. Masdeu-Bult贸
• 关键词：Carbonates ; Carbon dioxide ; Catalysis ; Chromium ; Tridentate Schiff bases
• 刊名：Journal of Molecular Catalysis A: Chemical
• 出版年：March, 2014
• 年：2014
• 卷：383-384
• 期：Complete
• 页码：143-152
• 全文大小：1278 K

文摘

New Cr(III) hexacoordinated complexes with tridentate NN鈥睴-donor Schiff base ligands, M(NN鈥睴)₂Cl, have been prepared. They form active catalytic systems for the coupling of epoxides and carbon dioxide in the presence of co-catalysts. Best results were obtained with the complex with N-(2-pyridylmethyl)-3,5-di-tert-butyl-salicylaldimine (1) ligand and a co-catalyst. Cyclohexene oxide reacts with carbon dioxide in the presence of these catalysts to form mixtures of polycarbonate (PC) (productivity up to ca. 900 g PC/g Cr) and cyclic carbonate depending on the co-catalyst and conditions employed. Cyclopentene, styrene and propylene oxides form selectively the cyclic carbonates at the conditions studied (epoxide conversion up to 97%). Although some of the co-catalysts are also active for the cycloaddition, the presence of both complex and co-catalyst has proved to be beneficial.