Enhanced Catalytic Activity of Aluminum Complexes for the Ring-Opening Polymerization of ε‑Caprolactone

• Published in: Inorganic chemistry 2017-07, Vol.56 (14), p.7998-8006
• Main Authors: Kosuru, Someswara Rao, Sun, Ting-Han, Wang, Li-Fang, Vandavasi, Jaya Kishore, Lu, Wei-Yi, Lai, Yi-Chun, Hsu, Sodio C. N, Chiang, Michael Y, Chen, Hsuan-Ying
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.7b00763

A series of dinuclear aluminum (Al2Pyr2) complexes bridged by two pyrazole ligands were synthesized, and their catalytic activity toward ring-opening polymerization of ε-caprolactone (CL) was investigated. Different types of the Al–N–N–Al–N–N skeletal ring were found among these Al2Pyr2 complexes. The butterfly form, L Thio 2 Al 2 Me 4 , exerted the highest catalytic activity for CL polymerization. κ2-CL coordination with both Al centers within the butterfly form L Thio 2 Al 2 Me 4 facilitates the initiation process. Generally speaking, the Al2Pyr2 complexes exhibited substantially higher catalytic activity for CL polymerization than literature examples such as β-diketiminate- or traiaza-bearing aluminum complexes. In fact, the Al2Pyr2 complexes can even carry out CL polymerization at room temperature.