Correlating Cobalt Net Charges with Catalytic Activities of the 2‐(Benzimidazolyl)‐6‐(1‐aryliminoethyl)pyridylcobalt Complexes toward Ethylene Polymerization

Abstract

The series of 2‐(benzimidazolyl)‐6‐(1‐aryliminoethyl)pyridylcobalt complexes was investigated by the DFT–QEq method to study the catalytic activity. The net charges on cobalt were evaluated at doublet and quartet states for the geometries, and correlated with the activities of these complex pre‐catalysts experimentally observed toward ethylene polymerization. Their activities are consistent with the trend of the effective net charges of cobalt. Based on the presence of methyl‐substituent on benzimidazolyl group or not, two families of cobalt complex pre‐catalysts show similar tendency according to the substituents on phenyl‐imino group. In other words, the substituents of methyl or proton on benzimidazolyl group made significant influence on the net charges of cobalt and their catalytic activities. However, the variation tendency between net charge and activity was similar within each class. Consistent with their iron analogous pre‐catalysts, the charge variation of cobalt is in line with the charge values on N3 atom within the complexes.