Polymerization of methyl methacrylate and other polar monomers with alkylaluminum initiators bearing bidentate and tridentate N‐ and O‐donor ligands

Abstract

Dimethylaluminum complexes bearing bidentate amidate, oxypyridine, and salicylaldimine N,O‐ligands and tridentate N,N′,N″‐pyridyliminoamide ligands were synthesized and spectroscopically characterized. The complexes were investigated in both neutral and borane‐activated cationic forms, along with bidentate N,N′‐ligated aluminum amidinates, as catalysts for the polymerization of methyl methacrylate, ϵ‐caprolactone, and propylene oxide. The neutral complexes generally did not carry out polymerization, but the polymerization/oligomerization of all three monomers was achieved when the various catalysts were activated with B(C6F5)3 or [Ph3C]+[B(C6F5)4]−. The N,O‐ligated cations were much less active for polymerization than the analogous, more stable N,N′‐ligated amidinate cations; both types of cationic complexes catalyzed the ring‐opening cationic polymerization of tetrahydrofuran. B(C6F5)3 and [Ph3C]+[B(C6F5)4]− also independently carried out the oligomerization of propylene oxide. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1633–1651, 2002

Multinuclear alkylaluminium macrocyclic Schiff base complexes: influence of procatalyst structure on the ring opening polymerisation of ε-caprolactone

“…2) was screened for the ROP of e-caprolactone under the same conditions (Table 3, entry 7). As reported by Baugh and Sissano, 17 complex 5 was found to be inactive under these conditions.…”

Metal catalysts for ε-caprolactone polymerisation

“…146 The simplest of the phenoxy-imine di-methyl aluminium complexes (complex 266, Chart 45) was found by us and others to be inactive for 3-caprolactone polymerisation. 85,147 However, the mixture of ligand L 4 H (Chart 45) and Et 3 Al gave rise to an active catalyst, although it displayed poor activities. In general, greater activities were obtained for catalysts supported by ligands possesing bulky ortho substituents on the phenolic residue such as L 5 H. A mixture of L 5 H with Et 3 Al gave rise to a very active species yielding 98% conversion after 1 h at room temperature and for a monomer : metal ratio of 300 : 1.…”

Aluminum Alkyl Complexes Bearing Salicylaldiminato Ligands: Versatile Initiators in the Ring-Opening Polymerization of Cyclic Esters

“…The cationic complexes indeed catalyzed the ringopening cationic polymerization of tetrahydrofuran. The polymerization of CL by the cationic species produced just traces of polymers or low molecular weight, alcohol-soluble polymer [35].…”

“…The neutral complexes usually did not promote polymerization, however the polymerization/oligomerization of all three monomers was achieved when the catalysts were activated with B(C 6 F 5 ) 3 cationic polymerization of tetrahydrofuran. The polymerization of CL by the cationic species produced just traces of polymers or low molecular weight, alcohol-soluble polymer [35].…”

“…The first report by Baugh and Sissano in 2002, relative to the synthesis and characterization of dimethylaluminum complexes bearing simple salicylaldiminato N,O-ligands without substituents on the aryl ring showed that these complexes, in their cationic form, catalyzed the ring-opening cationic polymerization of tetrahydrofuran [35]. However, polymerization of CL by the cationic species formed by activation with B(C 6 F 5 ) 3 produced just traces of polymers; when [Ph 3 C] + [B(C 6 F 5 ) 4 ] − was used, high yields of low molecular weight alcohol-soluble polymer were produced, probably due to the occurrence of transesterification processes during polymerization.…”