密度泛函理论研究聚烯烃催化剂取代基电子效应与催化活性的关系

 采用密度泛函 BP/DNP 优化了五组 (每组化合物具有相同的框架结构和不同电子效应的取代基) 共 18 个最受关注的烯烃配位聚合催化剂, 分别计算了每个化合物中心金属上的 Hirshfeld、Mulliken 和 QEq 电荷, 中心金属的 Fukui 指数以及化合物的 HOMO 和 LUMO 能量值, 然后将这些结构参数和配合物催化乙烯聚合的活性相关联. 结果发现, 中心金属的 QEq 电荷能正确反映取代基的电子效应, 且与化合物的 HOMO 以及 LUMO 能量值与催化活性之间有良好的相关性, 可用来预测催化剂活性; 而 Hirshfeld 和 Mulliken 电荷不能正确反映取代基的电子效应, 不适合计算这些化合物的中心金属电荷. 中心金属的 Fukui 指数受取代基电子效应影响较小, 和催化剂活性之间的相关性不明显.

Density Functional Theory Study on the Relationship between Polymerization Activity and Substituent Electronic Effect of Polyolefin Catalysts

Eighteen polyolefin catalysts have been calculated using the density functional theory in the BP/DNP level. These compounds are classified into five groups with similar steric effect and different electronic effect. The Hirshfeld, Mulliken, and QEq charges and Fukui indexes of the central metals and HOMO and LUMO engeries of these compounds have been calculated. The QEq charge of the central metal and HOMO and LUMO energies have good correlation with the polymerization activity and can be used to predict polymerization activity of new designed catalysts. However, the Hirshfeld and Mulliken charges cannot correctly reflect the electronic effect change of the substituents. The Fukui index changes indecisively with substituent electronic effect and has inconspicuous correlation with the polymerization activities of these compounds.