Catalytic Activities of Bis(pentamethylene)pyridyl(Fe/Co) Complex Analogues in Ethylene Polymerization by Modeling Method.

The catalytic activities of α,α'-bisimino-2,3:5,6-bis(pentamethylene)pyridyl(Fe/Co) chloride analogue complexes are quantitatively investigated by the multiple linear regression analysis (MLRA) method. From the point of view of the electronic and steric effects, seven structural descriptors are selected and calculated, including the Hammett constant ( F), effective net charge ( Q), energy difference (Δ E), HOMO-LUMO energy gap (Δε, Δε), open cone angle (θ), and bite angle (β). In order to get better model, the fitting analyses are carried out by using the combinations of four, three, two, and single descriptors. The calculation results show quite good correlation results. By using two descriptors ( Q, β), the catalytic activities for both the Fe and Co complexes individually and also the variation between Fe and Co (Fe-Co) analogue system can be well predicted with correlation coefficient values over 0.934. It is found that the effective net charge ( Q) plays the dominant role in determining the catalytic activities for Fe and Co complexes. Furthermore, the lower values of catalytic activities in Co complexes are mainly attributed to the decreasing values of Q.