Nickel complexes bearing [N,N] 2-pyridylbenzamidine ligands: Syntheses, characterizations, and catalytic properties for ethylene oligomerization
作者:Feng-Shou Liu、Hai-Yang Gao、Ke-Ming Song、Ling Zhang、Fang-Ming Zhu、Qing Wu
DOI:10.1016/j.poly.2009.02.023
日期:2009.5
A series of nickel(II) complexes with different steric and electronic substituted 2-pyridylbenzamidine ligands, [2,6-iPr(2)C(6)H(3)-N=C(R-1)-NH-(5-R-3, 6-R-2)Py]NiBr2 (R-1 = Ph, R-2 = H, R-3 = H, 1; R-1 = Ph, R-2 = H. R-3 = NO2, 2: R-1 = 4-CH3OC6H4, R-2 = H, R-3 = H, 3; R, = 4-CH3C6H4, R-2 = Me, R-3 = H, 4), have been synthesized in high yield and the solid state structures of 1, 2 and 4 have been crystallographically characterized. Activated with methyaluminoxane (MAO), 1-4 showed moderate turnover frequency (TOF) for ethylene oligomerization in dichloromethane. The influences of the ligand structure on catalytic properties were studied. Complex 2 with an electron-withdrawing group revealed the highest TOF of up to 11.7 x 10(3) mol ethylene/(mol Ni h). Moreover, the reaction temperature and Al/Ni molar ratio were also examined in detail. (C) 2009 Elsevier Ltd. All rights reserved.