Phenyl group charge delocalization into

Laali et al. have characterized carbocations generated from substituted polycyclic aromatic compounds. The related cation 157 is a true aryl-methyl-type ion, whereas cations 158 have arenium ion character because the strongly electron-withdrawing a-CF3 group enhances charge delocalization into the pyrenyl and phenyl groups. 

Due to coulombic repulsion, there is also less charge delocalization into the phenyl group. The diminished neighboring group participation (stabilization) is one of the characteristics of superelectrophilic activation.16 In the case of dication 45, the aryl group is less capable of donating electron density to either carbenium center. 

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