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Ti (IV) Complexes with Bidentate O ‐Chelating N ‐Heterocyclic Carbenes for Use in the Homopolymerization of Ethylene and Its Copolymerization with Cyclic Olefins
Author(s) -
van der Ende Melita,
Hauser Philipp M.,
Lienert Christina,
Wang Dongren,
Frey Wolfgang,
Buchmeiser Michael R.
Publication year - 2019
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201801669
Subject(s) - chemistry , ligand (biochemistry) , denticity , ethylene , medicinal chemistry , chelation , deprotonation , polymer chemistry , catalysis , titanium , crystal structure , stereochemistry , crystallography , organic chemistry , ion , biochemistry , receptor
The synthesis of titanium (IV) complexes bearing bidentate O ‐chelating N ‐heterocyclic carbenes (NHCs) is reported. Double deprotonation of the respective NHC precursor ligand and further reaction with one equivalent of TiCl 4 ⋅THF 2 leads to the formation of complexes Ti‐1 – Ti‐3 of the general formula TiCl 3 (NHC‐R‐O)(THF), (NHC‐R‐O=1‐(2,6‐diisopropylphenyl)‐3‐(2‐O‐phenyl)‐4,5‐dihydroimidazol‐2‐ylidene, 1‐(mesityl)‐3‐(2‐O‐phenyl)‐4,5‐dihydroimidazol‐2‐ylidene, 1‐(2,6‐dimethylphenyl)‐3‐(2‐O‐phenyl)‐4,5‐dihydroimidazol‐2‐ylidene). Furthermore, these Ti‐(NHC‐R‐O) trichloride complexes can be reacted with the bulky aryloxo ligands 2,6‐di t Bu‐4‐methylphenolate and 2,2’,4,4’,6,6’‐hexa‐ i Pr‐terphenoxide, respectively, to form the mixed titanium (aryloxo)(NHC‐R‐O) dichloride pre‐catalysts Ti‐4 – Ti‐6 . Single‐crystal X‐ray structures of complexes Ti‐1 , Ti‐5 and Ti‐6 are presented. Depending on the aryloxo ligand used, the complexes possess either a trigonal bipyramidal or square pyramidal ligand sphere. The propensity of Ti‐1 , Ti‐4 – Ti‐6 to homopolymerize ethylene and to copolymerize ethylene with norborn‐2‐ene (NBE) and cyclopentene (CPE), respectively, was investigated and access to high‐molecular weight (co‐)polymers with such complexes is disclosed.