Bimetallic Chromium Catalysts with Chain Transfer Agents: A Route to Isotactic Poly(propylene oxide)s with Narrow Dispersities. Issue 20 (25th April 2018)

• Record Type: Journal Article
• Authors: Morris, Lilliana S.; Childers, M. Ian; Coates, Geoffrey W.
• Is Part Of: Angewandte Chemie international edition. Volume 57:Issue 20(2018)
• Page Start: 5731
• Page End: 5734
• Publication Date: 2018-04-25
• Subjects: bimetallic catalysts -- chain transfer -- homogeneous catalyst -- polyether -- polymerization; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201801380
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Bimetallic chromium catalysts are investigated for the enantioselective polymerization of propylene oxide. The catalyst is composed of two salen chromium species linked by an alkyl chain, the length of which significantly impacts the rate of polymerization. While the use of a chloride initiator on the catalyst resulted in bimodal molecular weight distributions, switching to a trifluoroacetate initiating group and adding a diol chain transfer agent afforded polymers of controllable molecular weight with low, unimodal dispersities. Abstract : Bimetallic catalysts composed of two chromium salen species linked by an alkyl chain were explored for epoxide polymerization. Complexes tethered by five or six methylene linkers were highly active and enantioselective for propylene oxide polymerization. Using a diol chain transfer agent and trifluoroacetate initiating groups, polymers of controllable molecular weight with low, unimodal dispersities were formed.