Isotactic rac-Lactide Polymerization with Copper Complexes: The Influence of Complex Nuclearity

• Published in: Angewandte Chemie International Edition Vol. 54; no. 46; pp. 13669 - 13672
• Main Authors: Fortun, Solène, Daneshmand, Pargol, Schaper, Frank
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 09.11.2015; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Alkoxides; Ambient temperature; Benzene; Coordination compounds; Copper; Copper - chemistry; COPPER COMPOUNDS; COPPER OXIDE; Crystallography, X-Ray; Dioxanes - chemistry; homogeneous catalysis; Isotactic; lactide; Models, Molecular; Molecular Structure; N ligands; Organometallic Compounds - chemistry; Polylactides; Polymerization; POLYMERS; ring-opening polymerization; copper; homogeneous catalysis; lactide; N ligands; ring-opening polymerization
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201505674

Diiminopyrrolide copper alkoxide complexes, LCuOR (OR1=N,N‐dimethylamino ethoxide, OR2=2‐pyridyl methoxide), are active for the polymerization of rac‐lactide at ambient temperature in benzene to yield polymers with Mw/Mn=1.0–1.2. X‐ray diffraction studies showed bridged dinuclear complexes in the solid state for both complexes. While LCuOR1 provided only atactic polylactide, LCuOR2 produced partially isotactic polylactide (Pm=0.7). The difference in stereocontrol is attributed to a dinuclear active species for LCuOR2 in contrast to a mononuclear species for LCuOR1. It takes two: Diiminopyrrolide copper alkoxide complexes, LCuOR (OR1=N,N‐dimethylamino ethoxide, OR2=2‐pyridyl methoxide), are active for the polymerization of rac‐lactide at ambient temperature in benzene. While LCuOR1 provides only atactic polylactide, LCuOR2 produces partially isotactic polylactide. The difference in stereocontrol is attributed to a dinuclear active species for LCuOR2 in contrast to a mononuclear species for LCuOR1.