As the experimental results showed the higher activity of the catalyst A bearing iso-propyl substituents on ortho positions and acenaphtene group on the backbone, catalysts B and C with differences in the backbone and substituents exhibited lower productivities, respectively. This results along with some reasons also can be observed in some other literature, however, we studied on the theoretical and topological parameters, deeply. In addition to the level of energy in the catalyst structure, there are some parameters in relation with the activity. To clarify, as higher Mulliken charge on the metal center is good for monomer uptake, but less shielding effects of the active center can cause to deactivation. The results are listed in table 1. Higher shielding of axial sites, electron density, chemical hardness and lower HF energy and weaker electrophilicity index indicated characteristics of an effective catalyst in polymerization of olefin.

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