Zirconium vs Aluminum Salalen Initiators for the Production of Biopolymers

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• 作者：Sarah M. Kirk ; Gabriele Kociok-Köhn ; Matthew D. Jones
• 刊名：Organometallics
• 出版年：2016
• 出版时间：November 28, 2016
• 年：2016
• 卷：35
• 期：22
• 页码：3837-3843
• 全文大小：390K
• ISSN：1520-6041

文摘

Herein we report the synthesis and full characterization (NMR and solid-state structures) for a series of Zr(IV), Hf(IV), and Al(III) salalen complexes, together with salen bimetallic counterparts. With the salalen ligand, 1H₂, monometallic complexes were observed in solution and solid state. Complex Zr(1)(OⁱPr)₂ was able to produce isotactic polylactide (PLA) from rac-lactide (P_m up to 0.85) in solution at 50 °C; in the melt (130 °C) this reduced to ca. 0.75. Al(1)Me was significantly less active and produced PLA with only a very modest isotactic enchainment (P_m ≈ 0.6). Zr(1)(OⁱPr)₂ was also able to produce copolymers with lactide and ε-caprolactone, producing copolymers of a “blocky” nature.