508167-99-5Relevant academic research and scientific papers
Fluoro-substituted 2,6-bis(imino)pyridyl iron and cobalt complexes: High-activity ethylene oligomerization catalysts
Chen, Yaofeng,Qian, Changtao,Sun, Jie
, p. 1231 - 1236 (2003)
Six five-coordinate difluoro-substituted 2,6-bis(imino)pyridyl iron and cobalt complexes, [{2,6-(2,X-F2C6H3N=CCH3)2 C5H3N}MCl2] (X = 6, M = Fe (1), Co (2); X = 5, M = Fe (3), Co (4)); X = 4, M = Fe (5), Co (6)), were synthesized by reactions of the corresponding bis-(imino)pyridyl ligands with FeCl2·4H2O or CoCl2 in tetrahydrofuran (THF). However, a reaction between 2,6-diacetylpyridinebis(2,6-difluoroanil) and FeCl2·4H2O in CH3CN provided the ion-pair complex [Fe{2,6-(2,6-F2C6H3 N=CCH3)2C5H3 N}2]2+[FeCl4]2- (7) instead of a five-coordinate complex. The molecular structures of complexes 3 and 6 were determined by X-ray diffraction. The catalytic activities of complexes 1-7 for ethylene oligomerization were studied using modified methylaluminoxane (MMAO) as cocatalyst. At 60°C and 10 atm of ethylene pressure, the iron complexes 1, 3, and 5 show very high activities: 4.07 × 107, 9.33 × 107, and 11.1 × 107 g/((mol of cat.) h), respectively. The oligomers formed consist mainly of dimer, trimer, and tetramer, with approximately 90% of the products being in the range of C4-C8. The complexes 1, 3, and 5 also exhibit high selectivity for linear α-olefins: >98% (complex 1) and >93% (complexes 3 and 5). The cobalt complexes 2, 4, and 6 and the ion-pair iron complex 7 are inactive for ethylene oligomerization.
