Syntheses, Structures, and Catalytic Ethylene Oligomerization Behaviors of Bis(phosphanyl)aminenickel(II) Complexes Containing N ‐Functionalized Pendant Groups

Several N ‐functionalized bis(phosphanyl)amine ligands respectively containing benzyl, furfuryl, thiophene‐2‐methyl, thiophene‐2‐ethyl, and 2‐picolyl groups ( 1a – e ) were synthesized and characterized. The ligands reacted with (DME)NiBr 2 in CH 2 Cl 2 to give their corresponding nickel complexes [Ph 2 PN(R)PPh 2 NiBr 2 ] [R = CH 2 C 6 H 5 ( 2a ), CH 2 C 4 H 3 O ( 2b ), CH 2 C 4 H 3 S ( 2c ), CH 2 C 5 H 4 N ( 2d ), and CH 2 CH 2 C 4 H 3 S ( 2e )]. The structures of these complexes were established by single‐crystal X‐ray crystallography. All these nickel complexes were highly active towards ethylene oligomerization in the presence of methylaluminoxane or Et 2 AlCl, producing a high content of butene (C4). Especially for 2e , which contains a thiophene‐2‐ethyl pendant group, the oligomerization products obtained at –40 °C contained 95.9 mol‐% C4 fraction with 100 mol‐% 1‐butene. Over 50 °C, however, these nickel complexes underwent Friedel–Crafts alkylation of toluene with ethylene and the olefin oligomers.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)