Correlating net charges and the activity of bis(imino)pyridylcobalt complexes in ethylene polymerization

•Cobalt complex was studied by DFT–QEq method to investigate catalytic activities.•Effective net charge on cobalt at doublet reflected good correlation with activity.•Catalysis activities increase with higher effective net charges on cobalt atom.•Energy differences at doublet and quartet were independent on substituents change.

A series of unsymmetrical bis(imino)pyridylcobalt complexes was investigated by DFT–QEq method to correlate the net charges of cobalt center and their catalytic activities. The effective net charge values on cobalt atom, calculated by QEq method at doublet spin state, reflected the influences of substituents within their ligands. The catalytic activities of these cobalt complexes in ethylene polymerization continuously increase along with higher values of the effective net charges on cobalt atom. The energy differences at doublet and quartet states kept the constant tendency for the cobalt complexes without the steric influences of substituents within ligands.

Graphical abstractApproved by DFT–QEq method, the catalytic activities of bis(imino)pyridylcobalt complexes in ethylene polymerization continuously increase along with higher values of the effective net charges on cobalt atom.Figure optionsDownload full-size imageDownload as PowerPoint slide