Dizinc Lactide Polymerization Catalysts: Hyperactivity by Control of Ligand Conformation and Metallic Cooperativity |
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| Authors: | Arnaud Thevenon Dr. Charles Romain Michael S. Bennington Dr. Andrew J. P. White Hannah J. Davidson Prof. Sally Brooker Prof. Charlotte K. Williams |
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| Affiliation: | 1. Department of Chemistry, Imperial College London, South Kensington, UK;2. Department of Chemistry, University of Otago, Dunedin, New Zealand |
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| Abstract: | Understanding how to moderate and improve catalytic activity is critical to improving degradable polymer production. Here, di‐ and monozinc catalysts, coordinated by bis(imino)diphenylamido ligands, show remarkable activities and allow determination of the factors controlling performance. In most cases, the dizinc catalysts significantly out‐perform the monozinc analogs. Further, for the best dizinc catalyst, the ligand conformation controls activity: the catalyst with “folded” ligand conformation shows turnover frequency (TOF) values up to 60 000 h?1 (0.1 mol % loading, 298 K, [LA]=1 m ), whilst that with a “planar” conformation is much slower, under similar conditions (TOF=30 h?1). Dizinc catalysts also perform very well under immortal conditions, showing improved control, and are able to tolerate loadings as low as 0.002 mol % whilst conserving high activity (TOF=12 500 h?1). |
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| Keywords: | dinuclear zinc complexes homogeneous catalysis metal– metal cooperativity ring-opening polymerization structure– activity relationship |
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