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Syntheses, Structure, and Reactivity of Chiral Titanium Compounds: Procatalysts for Olefin Polymerization
Author(s) -
Sobota Piotr,
Przybylak Katarzyna,
Utko Józef,
Jerzykiewicz Lucjan B.,
Pombeiro Armando J. L.,
Guedes da Silva M. Fátima C.,
Szczegot Krzysztof
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010302)7:5<951::aid-chem951>3.0.co;2-f
Subject(s) - chemistry , maltol , titanium , catalysis , medicinal chemistry , guaiacol , reactivity (psychology) , alkoxide , organic chemistry , cyclopentadienyl complex , polymer chemistry , medicine , alternative medicine , pathology
Titanium complexes with chelating alkoxo ligands have been synthesised with the aim to investigate titanium active centres in catalytic ethylene polymerisation. The titanium complexes cis ‐[TiCl 2 ( η 2 ‐maltolato) 2 ] ( 1 , 89 %), and cis ‐[TiCl 2 ( η 2 ‐guaiacolato) 2 ] ( 2 , 80 %) were prepared by direct reaction of TiCl 4 with maltol and guaiacol in toluene. The addition of maltol to [Ti(O i Pr) 4 ] in THF results in the formation of species [Ti(O i Pr) 2 (maltolato) 2 ] ( 3 , 82 %). The titanium compound cis ‐[Ti(OEt) 2 ( η 2 ‐maltolato) 2 ] ( 4 , 74 %) was obtained by the transesterification reaction of species 3 with CH 3 CO 2 Et. When compound 4 is dissolved in THF a dinuclear species [Ti 2 ( μ ‐OEt) 2 (OEt) 4 ( η 2 ‐maltolato) 2 ] ( 5 , 45 %) is formed. Reaction of [Ti(O i Pr) 4 ] with crude guaiacol in THF yields a solid, which after recrystallisation from acetonitrile gives [Ti 4 ( μ ‐O) 4 ( η 2 ‐guaiacolato) 8 ] ⋅ 4 CH 3 CN ( 6 , 55 %). In contrast, reaction of TiCl 4 with crude guaiacol in tetrahydrofuran affords [Ti 2 ( μ ‐O)Cl 2 ( η 2 ‐guaiacolato) 4 ] ( 7 , 82 %). Crystallographic and electrochemical analyses of these complexes demonstrate that maltolato and guaiacolato ligands can be used as a valuable alternative for the cyclopentadienyl ring. These complexes have been shown to be active catalysts upon combination with the appropriate activator.