Abstract
A series of discrete chromium(III) precatalysts, {[Cr(κ3-L1)] (1a.7H2O), {[Cr(κ3-L2)] (2a.5H2O), {[Cr(κ3-L3)] (3a.6H2O), {[Cr(κ3-L4)] (4a.10H2O), {[Cr(κ3-L5)] (5a.4H2O) and in-situ-generated chromium(III) precatalysts {[Cr(κ3-L1)] (1b), {[Cr(κ3-L2)] (2b), {[Cr(κ3-L3)] (3b), {[Cr(κ3-L4)] (4b), {[Cr(κ3-L5)] (5b) bearing 2,4-di-tert-butyl-6-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L1), 2,4-di-tert-butyl-6-{[2-RR-pyrazol-1-yl-ethylimino]-methyl}-phenol, R = H (L2), Me (L3), Ph (L4), and 2,4-di-tert-butyl-6-{[2-pyrid-2-yl-ethylimino]-methyl}-phenol (L5) are developed. The discrete precatalysts are characterized by IR spectroscopy, elemental analysis, and mass spectrometry. The in-situ-generated precatalysts afford a one-step process for screening chromium(III) complexes as ethylene polymerization catalysts. Upon activation with EtAlCl2, both types of precatalysts exhibit high catalytic activities up to 1.71 × 105 g mol(Cr)-1 h-1 for the formation of high-density polyethylene with molecular weights as high as 3.48 × 103 g mol-1. While the discrete precatalysts produce monomodal active catalysts at all conditions, the in-situ-generated precatalysts produce either monomodal or bimodal active catalysts, suggesting that, at certain conditions, two active catalysts are produced in the in situ reactions. (Chemical Equation Presented).
Original language | English |
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Pages (from-to) | 1767-1775 |
Number of pages | 9 |
Journal | Macromolecular Chemistry and Physics |
Volume | 215 |
Issue number | 18 |
DOIs | |
Publication status | Published - 1 Sept 2014 |
Keywords
- chromium
- ethylene
- polymerization
- salicylaldimine
ASJC Scopus subject areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Polymers and Plastics
- Organic Chemistry
- Materials Chemistry