Kumar Vanka, Mary Chan,Cory Pye and Tom Ziegler, Department of Chemistry, University of Calgary, Calgary, Alberta Canada T2N 1N4.

Cationic metallocene compounds of the type Cp2MR+ (Cp = C5H5, R= CH3, C2H5 etc.) have been the subject of intense scrutiny over the past few years due to their ability to act as olefin polymerisation catalysts. The role of solvents, activators and counterions in influencing the activities of these metallocene compounds has been extensively investigated in experimental studies but little theoretical work has been done in this area. The present investigation studies the activation of the catalyst precursor (1,2-Me2Cp)2ZrMe2 by a series of borane and aluminum based activators to form the corresponding ion-pairs. The relative ease of dissociation of the ion-pairs thus formed is also analysed. The role of the solvent (toluene) in the activation process is considered by studying the possibility of the formation of solvent separated ion-pair species in solution. The next part of the work consists of a study of the inhibitive processes that are possible at the start of the polymerisation i.e. various side reactions that are possible betweeen the cationic catalyst and other species that exist in solution, leading to dormant products. The competition between the monomer and the solvent for coordination to the cation in the presence of the counterion is also investigated. The calculations were carried out at the NL-P/LDA level. Solvation effects were incorporated using the Conductor Like Screening Model.