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.

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