title: Ring-opening polymerisation of rac-lactide mediated by cationic zinc complexes featuring P-stereogenic bisphosphinimine ligands.
abstract: The diastereomerically pure P-stereogenic bis(phosphinimine) ligands 4,6-(ArN[double bond, length as m-dash]PMePh)(2)dbf [Ar = 4-isopropylphenyl (Pipp): rac-4, meso-4; Ar = 2,6-diisopropylphenyl (Dipp): rac-4a; dbf = dibenzofuran] were synthesised and complexed to zinc using a protonation-alkane elimination strategy. The cationic alkylzinc complexes thus obtained, RZn[4,6-(ArN[double bond, length as m-dash]PMePh)(2)dbf][B(Ar')(4)] [Ar = Pipp, Ar' = C(6)H(3)(CF(3))(2): rac-6 (R = Et), meso-6 (R = Et), rac-7 (R = Me) meso-7 (R = Me); Ar = Dipp: rac-6a (R = Et, Ar' = C(6)H(3)(CF(3))(2)), rac-6b (R = Et, Ar' = C(6)F(5))] were investigated for their competency as initiators for the ring-opening polymerisation of rac-lactide. The formation of polylactide was achieved under relatively mild conditions (40 °C, 2-4 h) and the microstructures of the resulting polymers exhibited a slight heterotactic bias [polymer tacticity (P(r)) = 0.51-0.63].
authors.affiliation: Department of Chemistry and Biochemistry, University of Lethbridge, AB, Canada.
authors.forename: Hongsui
authors.initials: H
authors.lastname: Sun
authors.forename: Jamie S
authors.initials: JS
authors.lastname: Ritch
authors.forename: Paul G
authors.initials: PG
authors.lastname: Hayes
mesh_terms: D004146:Dioxanes / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*; D058105:Polymerization; D013237:Stereoisomerism; D015032:Zinc / Q000737:chemistry*
chemical_list: D004146:Dioxanes; D008024:Ligands; D009942:Organometallic Compounds; D010720:Phosphines; C091880:dilactide; D015032:Zinc