Polymerization of ethylene and propene promoted by binaphthyl-bridged Schiff base complexes of titanium

Strianese, Maria; Lamberti, Marina; Mazzeo, Mina; Tedesco, Consiglia; Pellecchia, Claudio

doi:10.1016/j.molcata.2006.05.046

Cited by 28 publications

(14 citation statements)

References 16 publications

(20 reference statements)

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“…That is most probably responsible for the differences discovered in activities of various complexes, depending on the type of substituent R 2 . The observation that the presence of an electron‐withdrawing group on phenolate rings increases the activity of the catalyst in ethylene polymerization is in agreement with the results presented by Strianese et al for binaphthyl‐bridged tetradentate Schiff base complexes of titanium,26 and by Kol et al for bis(phenolate) titanium catalysts in 1‐hexene polymerization 27. One can thus suppose that the presence of an electron‐withdrawing group at the para position improves the electrophilic nature of the vanadium active site, and in this way it increases the rate of the chain propagation reaction, and consequently the catalyst activity.…”

Section: Resultssupporting

confidence: 91%

Dichlorovanadium (IV) complexes with salen‐type ligands for ethylene polymerization

Białek

Czaja

2008

J. Polym. Sci. A Polym. Chem.

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Vanadium complexes with tetradentate salen‐type ligands were first time explored in ethylene polymerizations. The effects of the vanadium complex structure, the alkyl aluminum cocatalysts type (EtAlCl2, Et2AlCl, Et3Al, and MAO), and the polymerization conditions (Al/V molar ratio, temperature) on polyethylene yield were explored. It was found that EtAlCl2 in conjunction with investigated vanadium complexes produced the most efficient catalytic systems. It was shown, moreover, that the structural changes of the tetradentate salen ligand (type of bridge which bond donor nitrogen atoms and type of substituent on aryl rings) affected activity of the catalytic system. The complexes containing ligands with cyclohexylene bridges were more active than those with ethylene bridges. Furthermore, the presence of electron‐withdrawing groups at the para position and electron‐donating substituents at the ortho position on the aryl rings of the ligands resulted in improved activity in relation to the systems with no substituents (with the exception of bulky t‐Bu group). The results presented also revealed that all vanadium complexes activated by common organoaluminum compounds gave linear polyethylenes with high melting points (134.8–137.6 °C), high molecular weights, and broad molecular weight distribution. The polymer produced in the presence of MAO possesses clearly lower melting point (131.4 °C) and some side groups (around 9/1000 C). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6940–6949, 2008

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Section: Resultssupporting

confidence: 91%

Dichlorovanadium (IV) complexes with salen‐type ligands for ethylene polymerization

Białek

Czaja

2008

J. Polym. Sci. A Polym. Chem.

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“…Therefore our interest was drawn towards the study of chiral tetradentate biaryl‐iminophenolate ligand systems wherein the rigid biaryl bridge forces both the chlorides and imino nitrogen atoms to occupy cis coordination sites in C 1 and C 2 ‐symmetric complexes 7,9,10. Intriguingly, despite of the attractive octahedral symmetry and similar substitution pattern with the most active bis(salicylaldiminato) catalysts those with tetradentate ligands have only low activity in polymerization.…”

Section: Introductionmentioning

confidence: 99%

Ethene Polymerization Behavior of MAO‐Activated Dichloridotitanium Complexes Bearing Bi‐ and Tetradentate Salicylaldimine Derivatives

et al. 2010

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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 methylalumin-

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“…Titanium Schiff base complexes are used in catalytic asymmetric pinacol coupling of aromatic aldehydes [4], polymerization of ethene and propene [5], as precatalysts for aldehyde allylation [6], for asymmetric additions to aldehydes and the ring opening of cyclohexene oxide [7], for titanium-catalyzed enantioselective cyanation of aldehydes [8], and asymmetric oxidation of sulfides with H 2 O 2 [9]. Titanium complexes also catalyze the 3-component coupling of an isonitrile, a 1,1-disubstituted hydrazine, and an alkyne [10].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Crystal Structure and Electrochemical Studies of a Hydrazone Schiff Base Complex of Titanium(IV)

Hosseini‐Monfared

Nazari²,

Mayer³

et al. 2009

Zeitschrift Für Naturforschung B

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Polymerization of ethylene and propene promoted by binaphthyl-bridged Schiff base complexes of titanium

Cited by 28 publications

References 16 publications

Dichlorovanadium (IV) complexes with salen‐type ligands for ethylene polymerization

Dichlorovanadium (IV) complexes with salen‐type ligands for ethylene polymerization

Ethene Polymerization Behavior of MAO‐Activated Dichloridotitanium Complexes Bearing Bi‐ and Tetradentate Salicylaldimine Derivatives

Synthesis, Crystal Structure and Electrochemical Studies of a Hydrazone Schiff Base Complex of Titanium(IV)

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