Thevenon A, Romain C, Bennington MS, White AJP, Davidson HJ, Brooker S, Williams CK. Dizinc Lactide Polymerization Catalysts: Hyperactivity by Control of Ligand Conformation and Metallic Cooperativity.
Angew Chem Int Ed Engl 2016;
55:8680-5. [PMID:
27295339 PMCID:
PMC5089563 DOI:
10.1002/anie.201602930]
[Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Indexed: 11/08/2022]
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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