Details

Autor(en) / Beteiligte

• Zhang, Jialong
• Motta, Alessandro
• Gao, Yanshan
• Stalzer, Madelyn Marie
• Delferro, Massimiliano
• Liu, Boping
• Lohr, Tracy L
• Marks, Tobin J

Titel

Cationic Pyridylamido Adsorbate on Brønsted Acidic Sulfated Zirconia: A Molecular Supported Organohafnium Catalyst for Olefin Homo- and Co-Polymerization

Ist Teil von

• ACS catalysis, 2018-06, Vol.8 (6), p.4893-4901

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2018

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Here we report the combined application of high-resolution solid-state 13C–CPMAS-NMR and FT-IR spectroscopy, elemental analysis, kinetic poisoning/active site counting, variable dielectric constant medium, and DFT computation to characterize the surface chemistry of a pyridylamido hafnium complex (Cat1, L1-HfMe2, L1 = 2,6-diisopropyl-N-{(2-isopropylphenyl)­[6-(naphthalen-1-yl)­pyridin-2-yl]­methyl}­aniline) adsorbed on Brønsted acidic sulfated zirconia (ZrS). The spectroscopic and DFT results indicate protonolytic formation of organohafnium cations having a largely electrostatic pyridylamido-Hf-CH3 +···ZrS– interaction with elongated Hf···OZrS distances of ∼2.14 Å. High-molecular-weight polyethylenes and ethylene/1-octene copolymers are obtained with this supported catalyst without an activator/cocatalyst. The DFT calculations reveal that the first ethylene insertion into the Hf-methyl bond has a lower barrier than the corresponding insertion into the Hf-aryl bond of this single-site heterogeneous catalyst.