“…I ) currently attract attention as highly efficient and selective agents for producing polyolefins having unprecedented/useful architectures and processing characteristics. , The active species are thought to consist of cation−anion pairs (e.g. II ), and growing experimental evidence indicates that the nature of such ion pairing, as modulated by cocatalyst/counteranion (X - ) and solvent, has significant consequences for catalyst activity, chain transfer characteristics, and possibly stereoselectivity. In contrast to experimental efforts, theoretical studies of such catalysts, while greatly expanding our understanding, have focused almost exclusively on naked group 4 cations. − We communicate here preliminary results of the first ab initio computational investigation, including counteranion and solvation, of catalyst generation, catalyst−cocatalyst structural energetics, and the olefin activation/insertion reaction coordinate for a CGC-based ion pair; it is seen that counteranion and solvation effects are substantial.…”