Group 4 complexes of amine bis(phenolate)s and their application for the ring opening polymerisation of cyclic esters

Abstract

A series of amine bis(phenolate) ligand precursors and their group 4 metal complexes have been prepared, characterised by single-crystal X-ray diffraction, and tested for ring opening polymerisation of epsilon-caprolactone.

New Aryloxy and Benzyloxy Derivatives of Titanium as Catalysts for Bulk Ring‐Opening Polymerization of ϵ‐Caprolactone and δ‐Valerolactone

“…To the best of our belief, such polymerizations in the presence of an alcoholic initiator like BnOH has not been reported so far using titanium derivatives. [30,[35][36][37]41,[43][44][45][46]48] We also considered it appropriate to compare the results using different aryloxy compounds 1-18 to those using the benzyloxy derivatives 19 and 20, respectively. These polymerizations were performed under bulk conditions at 80°C using 1-20.…”

“…[49] Only a few compounds derived from these ligands have been employed towards the polymerization of CL. [30,[35][36][37]41,[43][44][45][46]48] The polymerizations described from such initiators have exclusively relied upon the coordination-insertion mechanism. [1] Systematic correlation between the structural compositions of such ligands with polymer properties along with any practical advantage on polymer microstructure is not available.…”

“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) with one or more alkoxide-based initiating groups. The establishment of such a principle has been documented recently by demonstrating the applications of alkoxides with a ligating backbone containing chiral phenoxyimine, [28] tris-(phenoxy)amine, [29] bis(β-ketoamidate), [30] bis(iminophenoxy), [31][32] N-heterocyclic carbene, [33] bis(phenoxy)-amine, [34][35][36] pyrrolylamine, [37] tris(alkoxy), [38][39] tris(alkoxy)-amine, [40][41][42] bis(amido), [43] chalcogen-bridged bis(aryloxy) [44] and methylene-bridged bis(phenoxy) [45] derivatives. In addition, there are reports employing titanium n-butoxide, zirconium n-propoxide [46] and titanium phenoxide [47] as initiators.…”

Synthesis, Isolation and Structural Investigation of Schiff‐Base Alkoxytitanium Complexes: Steric Limitations of Ligand Coordination

“…[23][24][25][26][27][28][29][30] Considerable attention has also focused on the use of group 4 metal alkoxide complexes in the ring-opening polymerisations of cyclic esters such as lactic acid and ε-caprolactone. [31][32][33][34][35] As part of a more general study of the chemistry of titanium alkoxides, we and others have been interested in the use of similar complexes for a range of Lewis acid mediated reactions and polymerisations. [31,32,36,37] Herein we report the results of a synthetic and structural investigation of the stereochemical control possible by steric variation of ligands, specifically at the imine substituent.…”

“…[31][32][33][34][35] As part of a more general study of the chemistry of titanium alkoxides, we and others have been interested in the use of similar complexes for a range of Lewis acid mediated reactions and polymerisations. [31,32,36,37] Herein we report the results of a synthetic and structural investigation of the stereochemical control possible by steric variation of ligands, specifically at the imine substituent.…”