THE DYNAMICS STUDY OF METALLOCENE CATALYST USING MOLECULAR-DYNAMICS

Molecular dynamics (MD) simulation was applied to investigate the dyna mics of metallocene catalyst. We introduced a cocatalyst, large substi tuents on cyclopentadienyl (Cp) ring, and a longer polymer chain, alon g with a cationic active center. The study on interaction between the active center and the cocatalyst revealed that one or two fluorines of (C6F5)(4)B- are coordinated to the unsubstituted coordination space i n the most stable state. A metastable state was also found, where (C6F 5)(4)B- interacts with the whole active center, and moreover one or tw o fluorines come closer to a Si atom. The mobility of the polymer chai n bonded to a higher isospecific metallocene active center was found t o be more retarded than that bonded to a lower stereospecific metalloc ene active center. The investigation of the dynamics of polymer chain using our MD simulations would allow us to predict the stereospecifici ty of various metallocene catalysts. (C) 1998 Elsevier Science B.V. Al l rights reserved.