Bulky iminophosphine‐based nickel and palladium catalysts bearing 2,6‐dibenzhydryl groups for ethylene oligo‐/polymerization
Qitong Wu, Wenbin Wang, Guoyong Xu, Wenmin Pang, Yougui Li, Chen Tan, Fuzhou Wang
Abstract
A series of 2,6‐dibenzhydryl substituted bulky Ni and Pd complexes containing P,N‐chelating ligands, {[2,6‐(Ph 2 CH) 2 ‐4‐R‐C 6 H 2 ‐N=CH‐C 6 H 4 ‐2‐PPh 2 ]MX 2 ; MX 2 =NiBr 2 ; R = Me ( Ni1 ); R = F ( Ni2 ); MX 2 =PdCl 2 , R = Me ( Pd1 )}, have been prepared and used as catalyst precursors for ethylene oligo‐/polymerization. Compared to the corresponding 2,6‐diisopropyl Ni catalyst, these bulky Ni precatalysts activated by Et 2 AlCl exhibited excellent catalytic performance toward ethylene polymerization with activity of up to 1.90 × 10 5 g PE (mol Ni) −1 h −1 , and result in semicrystalline PEs with high molecular weight. The catalytic performance of these bulky P,N‐type complexes was significantly improved by introducing two ortho‐ dibenzhydryl on the N‐aryl substituents. However, the formation of C 10 –C 24 oligomers were generated using their palladium catalysts through ethylene oligomerization at high temperatures.