Sterically Less-Hindered Half-Titanocene(IV) Phenoxides: Ancillary-Ligand Effect on Mono-, Bis-, and Tris(2-Alkyl-/arylphenoxy) Titanium(IV) Chloride Complexes
- Authors
- Kim, Tae-Jin; Kim, Sung-Kwan; Kim, Beom-Jun; Son, Ho-Jin; Hahn, Jong Sok; Cheong, Minserk; Mitoraj, Mariusz; Srebro, Monika; Piekos, Lukasz; Michalak, Artur; Kang, Sang Ook
- Issue Date
- 2010
- Publisher
- WILEY-BLACKWELL
- Keywords
- alkylation; density functional calculations; polymerization; titanium
- Citation
- CHEMISTRY-A EUROPEAN JOURNAL, v.16, no.19, pp.5630 - 5644
- Indexed
- SCIE
SCOPUS
- Journal Title
- CHEMISTRY-A EUROPEAN JOURNAL
- Volume
- 16
- Number
- 19
- Start Page
- 5630
- End Page
- 5644
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/118571
- DOI
- 10.1002/chem.201000191
- ISSN
- 0947-6539
- Abstract
- A series of mono-, his-, and tris(phenoxy)-titanium(IV) chlorides of the type [Cp*Ti(2-R-PhO)(n)Cl(3-n) (n=1-3; Cp*=pentamethylcyclopentadienyl) was prepared, in which R=Me, iPr, tBu, and Ph. The formation of each mono-, bis-, and tris(2-alkyl-/aryl-phenoxy) series was authenticated by structural studies on representative examples of the phenyl series including [Cp*Ti(2-Ph-PhO)Cl(2)] (1PhCl2), [Cp*Ti(2-Ph-PhO)(2)Cl] (2PhCl), and [Cp*Ti(2-Ph-PhO)(3)] (3 Ph). The metal-coordination geometry of each compound is best described as pseudotetrahedral with the Cp* ring and the 2-Ph-PhO and chloride ligands occupying three leg positions in a piano-stool geometry. The mean Ti-O distances, observed with an increasing number of 2-Ph-PhO groups, are 1.784(3), 1.802(4), and 1.799(3) angstrom for 1PhCl2, 2 PhCl, and 3Ph, respectively. All four alkyl/aryl series with Me, iPr, tBu, and Ph substituents were tested for ethylene homopolymerization after activation with Ph(3)C(+)[B(C(6)F(5))(4)](-) and modified methyaluminoxane (7% aluminum in iso-par E; mMAO-7) at 140 C. The phenyl series showed much higher catalytic activity, which ranged from 43.2 and 65.4 kg(mmol of Ti.h)(-1), than the Me, iPr, and tBu series (19.2 and 36.6kg(mmol of Ti-h)(-1)). Among the phenyl series, the bis(phenoxide) complex of 2PhCl showed the highest activity of 65.4 kg (mmol of Ti.h)(-1). Therefore, the catalyst precursors of the phenyl series were examined by treating them with a variety of alkylating reagents, such as trimethylaluminum (TMA), triisobutylaluminum (TIBA), and methylaluminoxane (MAO). In all cases, 2 PhCl produced the most catalytically active alkylated species, [Cp*Ti(2-Ph-PhO)MeCl]. This enhancement was further supported by DFT calculations based on the simplified model with TMA.
- Files in This Item
- There are no files associated with this item.
- Appears in
Collections - Graduate School > Department of Advanced Materials Chemistry > 1. Journal Articles
Items in ScholarWorks are protected by copyright, with all rights reserved, unless otherwise indicated.