title: Titanium-salen complexes as initiators for the ring opening polymerisation of rac-lactide.
abstract: A family of bis(iso-propoxide) titanium(IV) complexes supported by tetradentate Schiff base (salen) ligands has been synthesised and characterised, including a structural determination of N,N'-bis(6'-methylenimino-2',4'-di-tert-butylphenoxy)cyclohexyl-(1R,2R)-diamino titanium(IV) bis(iso-propoxide). Their suitability for initiating the ring-opening polymerisation of rac-lactide has been investigated. Polymerisation activities are shown to correlate with the electronic properties of the substituents within the salen ligand. In contrast to aluminium-salen initiators, electron-withdrawing substituents on the Schiff base ligand have a detrimental influence upon polymerisation activities, whereas the use of electron-donating alkoxy-functionalized ligands has allowed the highest recorded activity to date for a titanium-based initiator.
authors.affiliation: Imperial College London, Department of Chemistry, South Kensington Campus, London, UK SW7 2AZ.
authors.forename: Charlotte K A
authors.initials: CK
authors.lastname: Gregson
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Blackmore
authors.forename: Vernon C
authors.initials: VC
authors.lastname: Gibson
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Long
authors.forename: Edward L
authors.initials: EL
authors.lastname: Marshall
authors.forename: Andrew J P
authors.initials: AJ
authors.lastname: White