The Electronic and Steric Effects Influence on Catalytic Activity of 2-Azacyclyl-6-aryliminopyridylmetal Complexes in Polyethylene Reaction
The electronic and steric effects are two critical factors affecting the activity.1,2 In view of electronic effects, we found that the effective net charge, spin states energy difference (△E) and HOMO-LUMO energy gap (△ε) presented clear correlations with catalytic activity.2b Moreover, the energy gaps (△ε)decreased dramatically from about 60 kcai/moi within pre-catalyst to about 0 kcal/mol within active species (as shown in Figure 1a), indicating the important activating role played by co-catalyst in ethylene reaction.The multiple linear regression analysis (MLRA) was performed to investigate both electronic and steric effects of ligands on the catalytic activities of the transition metal complexes in ethylene oligo/polymerization.3 The Hammett constants (F) and effective net charge (Q) are used to describe the electronic effect, meanwhile the steric effect is illustrated by open cone angle (θ) and bite angle (β), the complex structure and model of the multiple linear regression were shown in Figure 1b.Four series of 2-azacyclyl-6-aryliminopyridylmetal (Fe, Co and Cr) analog complexes are calculated and the catalytic activity can be efficiently analyzed through taking both the electronic and steric effects into account.3 All of the obtained correlation coefficient R2 values are over 0.93.The electronic effect is dominant in determining the catalytic activities for Fe and Co complexes;however, the steric effect plays a major role in controlling activities of Cr complexes.
Jun Yi Wenhong Yang Wen-Hua Sun
Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences,Beijing 100190 China
国际会议
9th International Symposium on High-Tech Polymer Materials(第9届国际高技术高分子材料学术会议)(HTPM-9)
郑州
英文
106-106
2016-07-11（万方平台首次上网日期，不代表论文的发表时间）