Mechanistic aspects of ethylene polymerization by iron(II)-bisimine pyridine catalysts: A combined density functional theory and molecular mechanics study
The polymerization of ethylene by Fe(II)-bisimine pyridine catalysts was investigated theoretically at two different computational levels. Using purely DFT methods, the activity of a 'generic' model system was studied. The lack of available propagation and termination pathways available to the simplified model complex underscores the importance of steric effects in this system. More sophisticated QM/MM techniques were then employed to model the entire 'real' system, and the role of the bulky aryl groups in suppressing ethylene coordination and attendant decomposition pathways was demonstrated. While the quintet spin state exhibited by the catalyst precursor was not involved in the polymerization cycle, which was found to proceed almost exclusively via the singlet potential energy surface, several key transition states were demonstrated to proceed via spin-state change to triplet species.
Publication Source (Journal or Book title)
Poli, R., Smith, K., & Ziegler, T. (2000). Mechanistic aspects of ethylene polymerization by iron(II)-bisimine pyridine catalysts: A combined density functional theory and molecular mechanics study. Chemtracts, 13 (5), 309-315. Retrieved from https://digitalcommons.lsu.edu/chemistry_pubs/1652