Binuclear late transition metal catalysts for α-olefin polymerization

Two binuclear α-diimine nickel (II) catalyst (A) {2,6-diisopropyl-C6H4-N=C-(C10H6)-C=N-C6(CH3)4-N=C- (C10H6)-C=N-2,6- diisopropyl-C6H4}{NiBr2} and {2,6- diisopropyl-C6H4-N=C-(C10H6)-C=N-C6H4-N=C- (C10H6)-C=N-2,6- diisopropyl-C6H4}{NiBr2} (B) were prepared under controlled conditions and used in 1- hexene homopolymerization. The catalysts have a rigid bridge which catalyst A has four methyl groups on center ring while in catalyst B hydrogen atoms cause less steric effects. To investigate ortho-substituent impact (methyl) on catalyst behavior, the experiments were performed under similar condition and diethylaluminum chloride (DEAC) was used as cocatalyst. The binuclear complexes were compared in catalytic performance which catalyst A showed higher activity versus catalyst B. The highest activities for catalyst A were at lower [Al]/[Ni] molar ratio in comparison to catalyst B.