Metallocence based single-site homogeneous catalysts are superior to traditional Ziegler-Natta type catalysts and feature well defined molecular structures that made theoretical investigations into the mechanistic aspects of polymerization possible. The catalyst precursor has the general formula L₂M(R)₂ where M is a transitional metal center, L is a ligand and R is an alkyl group. A Lewis acid (A) is used to abstract an alkyl group to produce the active cationic catalyst [L₂M(R)⁺ ]. The present investigation focuses on the equilibria between various types of ion-pairs formed by the reaction of this cation with the counterion [RA- ], the solvent, or the olefin. The potential energy surface for the formation of various ion-pairs will be described. The influence of solvation, the Lewis acid and the structure of the catalyst precursor will be discussed. The calculations were carried out on experimentally obtained substrates: fluoroarylboranes were paired with either constrained geometry, mono- or bis- cyclopentadienyl precursors at the NL-P/LDA level. Solvation effects were incorporated by single point calculations using the Conductor-like Screening Model, and where appropriate, a single molecule of the solvent was included to model tightly bound solvent-solute interactions.