Activation effect of metal chlorides in post-metallocene catalytic systems for ethylene polymerization: A DFT studyстатья
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Дата последнего поиска статьи во внешних источниках: 7 декабря 2016 г.
Аннотация:This work is devoted to the DFT study of the activation effect of metal chlorides (MgCl2, LiCl, ZnCl2, CaCl2) in ethylene polymerization reactions on post-titanocene complexes LTi(Y)Cl (1), where L is the bidentate saligenin type ligand, Y is alkyl group or Cl. The activation effect of metal chlorides is caused by secondary complexation reactions between 1 and metal chlorides. In accordance with previously reported experimental data, our DFT calculations predict that the most probable catalytic particles in the systems based on MgCl2 possess higher reactivity with respect to ethylene molecule than in the systems based on LiCl. One could expect a higher catalytic activity for CaCl2 than for MgCl2, but for ZnCl2 the catalytic activity should be the lowest. Results of our calculations show that at least three different hetero-trinuclear compounds of Ti, Mg and Al have similar reactivity towards ethylene molecule. This result explains Mw/Mn indexes > 2 measured earlier for one of the systems under the study with R3Al (R=Me, t-Bu) as activators.