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Titanium–Imido Complexes with Pendant Groups – Synthesis, Characterization, and Evaluation of Their Role as Precatalysts for Ethylene Polymerization
Author(s) -
Nguyen VietHoang,
Vendier Laure,
Etienne Michel,
DespagnetAyoub Emmanuelle,
Breuil PierreAlain R.,
Magna Lionel,
Proriol David,
OlivierBourbigou Hélène,
Lorber Christian
Publication year - 2012
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.201101005
Subject(s) - chemistry , pyridine , denticity , ethylene , polymerization , ligand (biochemistry) , thiophene , polymer chemistry , proton nmr , chelation , titanium , furan , nuclear magnetic resonance spectroscopy , crystal structure , stereochemistry , medicinal chemistry , crystallography , catalysis , organic chemistry , polymer , biochemistry , receptor
The synthesis of several anilines (Ar PG NH 2 ) substituted in the ortho position with pendant groups (PGs, terminated by potentially coordinative arene, thienyl, furanyl, or pyridyl functionalities) was accomplished by a two‐ to five‐step synthesis in good yields. The Ar PG NH 2 proligands were used for the preparation of titanium complexes starting from Ti(NMe 2 ) 4 in the presence of excess Me 3 SiCl. Complexes of the general formula [Ti(NAr PG )Cl 2 (NHMe 2 ) x ] ( x = 1, 2), which are supported by a terminal imido functionality, were obtained in 60–95 % yield. The nature of the pendant group influences the coordination mode of the ligand. Although only monodentate imido linkages have been observed with ligands where PG is arene, thiophene, and furan, ligands with substituted pyridine sidearms lead to chelating imido–donor functionalities. The potential hemilabile behavior of some imido–donor ligands, which results from the reversible coordination of the side arm, was studied by variable‐temperature 1 H NMR spectroscopy. These compounds were evaluated as precatalysts for ethylene polymerization with various aluminum cocatalysts. Ultrahigh molecular‐weight (UHMW) polyethylenes were obtained. All compounds were fully characterized by spectroscopic methods ( 1 H and 13 C NMR), and elemental analysis and some were also characterized by single‐crystal X‐ray diffraction.