engleski

Towards highly powerful neutral organic superacids - a DFT study of some polycyano derivatives of planar hydrocarbons

Density functional theory (DFT) calculations at B3LYP/6-311+G(2d, p)//B3LYP/6-31G(d) level have been carried out on indene, cyclopentaphenanthrene and 1H-phenalene and their heptacyano and nonacyano derivatives, respectively, in order to examine their acidities in the gas-phase and DMSO. It is found that polycyano derivatives represent powerful organic superacids, the most acidic being nonacyano-1H-phenalene. The origin of the highly pronounced acidity is identified as a strong anionic resonance in the resulting conjugate base. Comparison of the calculated dHacid value for 1H-phenalene with the experimental NIST value shows that the latter is too large by 8-11 kcal mol-1. A possible reason for this error is briefly discussed.

acidity; neutral organic acids; superacidity; aromaticity; prototropic tautomerism

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