Two Novel synthesized binuclear catalysts were resulted which effect of ortho substituent on A1 and A2 catalyst activity was studied. There is optimum molar ratios of about [Al]:[Ni] = 1500:1 for catalyst A1 to reach the highest activity. Complex A2 which has more hindering and electronic effect on ortho substituent showed more activity than A1 in the optimum condition of polymerization. By increasing hindering especially on ortho-position of aryl rings, β-hydrogen elimination and chain transfer retard; because of reducing of monomer diffusion from ortho-position to metallic center, thus it enhances the average molecular weight. Based on aforementioned reason, A2 which has isopropyl groups on ortho position instead of methyl groups in complex A1 prove this issue as well.

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