Effect of chloride substitution on the performance of a benzhydryl-substituted bis(arylimino)pyridyl–cobalt ethylene polymerization catalyst

To address the impact of chloride substitution on the performance of a benzhydryl-substituted bis(arylimino)pyridyl–cobalt ethylene polymerization catalyst, this work reports a new family of unsymmetrical N' , N' , N'' -cobalt(II) chloride complexes, Co1 – Co5 , incorporating one fixed N -2-Me-4,6-bis(4,4 ' -dichlorodibenzhydryl)phenyl group while the other N -aryl group is sterically and electronically variable (aryl = 2,6-dimethylphenyl; 2,6-diethylphenyl; 2,6-diisopropylphenyl; 2,4,6-trimethylphenyl; 2,6-diethyl-4-methylphenyl). Full characterization of all five complexes is supported by representative X-ray structures of Co1 and Co2 that display distorted square pyramidal geometries. All cobalt complexes exhibited high activity, under activation with either methylaluminoxane (MAO) or modified MAO (MMAO), with levels reaching up to 14.74 × 10 6 (g of PE)·(mol of Co) –1 ·h –1 at 60 °C producing polyethylene (PE) wax ( M w range: 10.3–34.3 kg·mol –1 ) with high linearity and narrow dispersity ( M w / M n range: 2.1–2.5), highlighting their good control. With both aluminum activators, the most sterically demanding cobalt catalyst, Co3 , afforded the highest molecular weight polyethylene but the lowest catalytic activity.