title: Preparation of enantiomerically pure open calcocene and strontocene complexes and their application in ring opening polymerizations of rac-lactide.
abstract: The synthesis of C2 symmetric enantiomerically pure open Ca and Sr metallocenes, [(η(5)-pdl*)2Ca(thf)] (1) and [(η(5)-pdl*)2Sr(thf)2] (2) (pdl* = dimethylnopadienyl) is described and these complexes were fully characterized. The solid state structures confirm that the pdl* ligands coordinate exclusively with the less sterically demanding site to the Ca and Sr atoms. These complexes are active catalysts for the controlled ring opening polymerization (ROP) of rac-lactide to give heterotactically enriched polylactides (PL) with narrow polydispersities (PDI = 1.29-1.31) and without adding further activators.
authors: Institut für Anorganische und Analytische Chemie, Technische Universität, Braunschweig, Hagenring 30, 38106 Braunschweig, Germany. mwalter@tu-bs.de.
authors: Ann Christin
authors: AC
authors: Fecker
authors: Matthias
authors: M
authors: Freytag
authors: Peter G
authors: PG
authors: Jones
authors: Ning
authors: N
authors: Zhao
authors: Guofu
authors: G
authors: Zi
authors: Marc D
authors: MD
authors: Walter