Premium
Ethene Polymerization Behavior of MAO‐Activated Dichloridotitanium Complexes Bearing Bi‐ and Tetradentate Salicylaldimine Derivatives
Author(s) -
Pärssinen Antti,
Luhtanen Tommi,
Pakkanen Tapani,
Leskelä Markku,
Repo Timo
Publication year - 2010
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200900840
Subject(s) - chemistry , methylaluminoxane , cationic polymerization , polymerization , schiff base , catalysis , polymer chemistry , ligand (biochemistry) , titanium , medicinal chemistry , polyethylene , stereochemistry , organic chemistry , receptor , metallocene , polymer , biochemistry
New chiral bridged tetradentate (N 2 O 2 )Ti IV Cl 2 ‐type complexes bearing dimethylbiphenyl ( 1‐Ti – 3‐Ti ) and previously published binaphthyl‐bridged ( 4‐Ti ) complex were synthesized with high yields. This was achieved by treating the corresponding Schiff‐base ligand (H 2 L) precursors with Ti(NMe 2 ) 4 , followed by conversion of these diamido complexes to LTiCl 2 derivatives by the addition of excess of Me 3 SiCl. A series of unbridged titanium complexes 5‐Ti – 8‐Ti with similar substituents at the phenoxy group were studied and their polymerization properties, after methylaluminoxane (MAO) activation, compared with the above bridged complexes. It was found that the catalysts bearing chiral tetradentate biaryl‐bridged salicylaldimine ligands produce multimodal polyethylene (PE) with low activity [below 10 kg PE /(mol Ti h bar)] while their unbridged analogues provide activities that are 10–1000 times greater under similar reaction conditions. The reasons for this dramatic difference in polymerization activities are discussed based on the stabilities of the different cationic species configurations.