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Chromium complexes based on thiophene–imine ligands for ethylene oligomerization
Author(s) -
Ferreira Jorge,
Zilz Raquel,
Boeira Igor S.,
Silva Sabrina M.,
Casagrande Adriana C.A.,
Casagrande Osvaldo L.
Publication year - 2019
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.4697
Subject(s) - chemistry , methylaluminoxane , chromium , imine , catalysis , ethylene , medicinal chemistry , thiophene , ligand (biochemistry) , monomer , infrared spectroscopy , polymer chemistry , nuclear chemistry , stereochemistry , polymer , organic chemistry , polymerization , metallocene , biochemistry , receptor
A new set of Cr(III) complexes, {L}CrCl 3 (THF), based on thiophene–imine ( 2a , L = PhOC 6 H 4 (N═CH)‐2‐SC 4 H 3 ; 2b , L = PhOC 2 H 4 (N═CH)‐2‐SC 4 H 3 ; 2c , L = Ph(NH)C 2 H 4 (N═CH)‐2‐SC 4 H 3 ; 2d , L = PhOC 6 H 4 (N═CH)‐2‐SC 4 H 2 ‐5‐Ph; 2e , L = Ph(NH)C 2 H 4 (N═CH)‐2‐SC 4 H 2 ‐5‐Ph) have been prepared and characterized using elemental analysis and infrared spectroscopy. Upon activation with methylaluminoxane, all the chromium complexes generated active systems affording a nonselective distribution of α‐olefins with turnover frequencies in the range 9500–93 500 (mol ethylene) (mol Cr) −1 h −1 , and producing mostly oligomers (95.0–99.3 wt% of total products). Small amounts of polymer were produced in these oligomerization reactions (0.8–8.2 wt%). The catalytic activities were quite sensitive to the ligand environment. Moreover, the effects of oligomerization parameters (temperature, [Al]/[Cr] molar ratio, time) on the activity and on the product distribution were examined.