B3LYP calculations cation formation

The important field of ionic liquids, in most cases 1,3-dimidazolium salts (143) has been studied by IR and Raman spectroscopies supported by B3LYP calculations. Additionally, calculations of the heteroaromaticity (HOMA index) showed that cation formation causes a decrease of the aromaticity of the imidazole ring. However, when the R groups at positions 1,3 are benzyl or adamantyl, the aromatic nature of the heterocyclic moiety increases. Moreover, the electron distribution performed using the GAPT method indicated the positive charge delocalization in the imidazolium ring [143],... 

By theoretical calculations (B3LYP/6-31G ) four reaction pathways were investigated formation of endo or egzo product with initial bond formation to C2 or C3 in indole. For each mechanism theoretical 13C KIE were analysed and the best agreement of theoretical and experimental KIEs was found for the reaction involving the intermediacy of the radical cation 11, resulting from electrophilic aromatic substitution of indole at C3 by cyclohexadiene in the rate-limiting step ... 

The small association energy Eq predicted for the cations 1 suggests that at ambient conditions no significant cation-solvent interactions are present. This is supported by calculations which take entropy and temperature effects into account. These calculations show, for example, that the formation of 7 (X = Ph) is endergonic at 298 K (AG (7, X = Ph) = +14.6 kJ mol, at B3LYP/6-31G(d)). 

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