Synthesis of Mono- and Dinuclear Aluminum Complexes Bearing Aromatic Amino-Phenolato Ligands: A Comparative Study in the Ring-Opening Polymerization of Cyclohexene Oxide
Chen, Yongjie1; Li, Baoxia1; Wang, Yaorong1; Zhu, Xuehua2; Yuan, Dan1*（袁丹）; Yao, Yingming1*（姚英明）
1Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Dushu Lake Campus, Soochow University, Suzhou215123, People’s Republic of China
2School of Chemistry and Life Science, Suzhou University of Science and Technology, Suzhou 215009, People’s Republic of China
Inorg. Chem.2023, 62, 51, 21247–21256
Abstract:Dinuclear aluminum methyl complexes bearing aromatic diamine-bridged tetra(phenolato) ligands and the mononuclear aluminum methyl complex with the phenylamine-bridged bis(phenolato) ligand have been synthesized and characterized. Structure determination revealed that the Al–Al distances in these dinuclear aluminum complexes are tunable by the choice of the suitable aromatic backbone of the diamine-bridged tetra(phenolato) ligands. The catalytic behaviors of these mono- and dinuclear aluminum complexes for cyclohexene oxide (CHO) polymerization were investigated. The activities of these dinuclear Al complexes were observed to increase with the decrease of Al–Al distances, and the dinuclear Al complexes appeared to have better catalytic activity than the mononuclear Al complex, even if the Al–Al distance is as long as 9.401 Å. Dinuclear aluminum complex 2, with the shortest Al–Al distance (7.236 Å), showed the highest activity toward CHO polymerization with TOFs up to 6460 h–1in neat CHO at 30 °C. Furthermore, comparative kinetic studies revealed that the polymerization is first-order for CHO concentration, and the reaction orders for initiator concentration are different for the mono- and dinuclear Al complexes. The polymerization mechanism study revealed that both the methyl and phenolate groups were involved in the initiation process.
链接：https://pubs.acs.org/doi/10.1021/acs.inorgchem.3c03318
