Aluminium alkyl complexes [(OSSO)AlR] (1–3: R = Me, Et) were isolated in good yields from the protonolysis reactionofAlR3 withthecorrespondingtetradentate1,x-dithiaalkanediyl-bridgedbisphenols(1,4-dithiabutanediyl- bis(6-tert-butyl-4-methylphenol), etbmpH2; ortho-xylylenedithio-bis(6-tert-butyl-4-methylphenol), xytbmpH2). The monomeric structures of all three complexes were confirmed by X-ray diffraction studies. Complexes 1 and 2 have an isotypic packing arrangement. The aluminium center is coordinated by the etbmp ligand and one alkyl group with distortedtrigonalbipyramidalgeometry.Complex3showsCs symmetrywithsquarepyramidalgeometryaroundthe metal center. Substitution reaction of complex 1 with trityl alcohol gave the monomeric alkoxide complex [(etbmp)Al(OCPh3)] 4, which has a similar trigonal bipyramidal geometry around the aluminium atom as complex 1. In the presence of isopropanol, complexes 1–3 initiated the living ring-opening polymerization of rac-lactide (PDI = 1.03–1.06, Mw/Mn). The ligand structure influenced the tacticity of the obtained polymer, with complex 3 giving heterotactic-enriched polylactides.
Aluminium alkyl complexes supported by [OSSO] type bisphenolato ligands: synthesis, characterization and living polymerization of rac-lactide
OLIVA L.;
2005-01-01
Abstract
Aluminium alkyl complexes [(OSSO)AlR] (1–3: R = Me, Et) were isolated in good yields from the protonolysis reactionofAlR3 withthecorrespondingtetradentate1,x-dithiaalkanediyl-bridgedbisphenols(1,4-dithiabutanediyl- bis(6-tert-butyl-4-methylphenol), etbmpH2; ortho-xylylenedithio-bis(6-tert-butyl-4-methylphenol), xytbmpH2). The monomeric structures of all three complexes were confirmed by X-ray diffraction studies. Complexes 1 and 2 have an isotypic packing arrangement. The aluminium center is coordinated by the etbmp ligand and one alkyl group with distortedtrigonalbipyramidalgeometry.Complex3showsCs symmetrywithsquarepyramidalgeometryaroundthe metal center. Substitution reaction of complex 1 with trityl alcohol gave the monomeric alkoxide complex [(etbmp)Al(OCPh3)] 4, which has a similar trigonal bipyramidal geometry around the aluminium atom as complex 1. In the presence of isopropanol, complexes 1–3 initiated the living ring-opening polymerization of rac-lactide (PDI = 1.03–1.06, Mw/Mn). The ligand structure influenced the tacticity of the obtained polymer, with complex 3 giving heterotactic-enriched polylactides.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
