Synthesis and X-ray structures of new titanium(IV) aryloxides and their exploitation for the ring opening polymerization of epsilon-caprolactone

Matthew G Davidson; Matthew D Jones; Matthew D Lunn; Mary F Mahon

doi:10.1021/ic051708n

Synthesis and X-ray structures of new titanium(IV) aryloxides and their exploitation for the ring opening polymerization of epsilon-caprolactone

Inorg Chem. 2006 Mar 6;45(5):2282-7. doi: 10.1021/ic051708n.

Authors

Matthew G Davidson¹, Matthew D Jones, Matthew D Lunn, Mary F Mahon

Affiliation

¹ Department of Chemistry, University of Bath, Claverton Down, UK. m.g.davidson@bath.ac.uk

PMID: 16499394
DOI: 10.1021/ic051708n

Abstract

A series of titanium catecholates have been prepared and characterized by single-crystal X-ray diffraction studies. Complexes 1a-7a were synthesized by the reaction of 1 equiv of ligand with Ti(OiPr)4. All are dimers in the solid-state, in which a catechol bridges between two titanium centers. Electronic (nitro and methoxy groups) and steric (tert-butyl groups) effects of the ligand have been investigated. Complex 1b was synthesized by reaction of 2 equiv of ligand with Ti(OiPr)4. A dimer is again observed with the same bridging ligand together with a terminal catechol moiety. All complexes contain a coordinated 2-propanol ligand on each titanium center forming pseudo-octahedral metal centers. All complexes were tested for the ring-opening-polymerization of epsilon-caprolactone to afford polycaprolactone (PCL). Reasonable yields (up to 79%) were obtained at room temperature, and narrow molecular weight distributions (1.13-1.27) were observed for the PCL produced. The most active complex was found to be complex 1a, containing unsubsituted catechol ligands.