Naslov
In Search of Ultrastrong Bronsted Neutral Organic Superacids - A DFT Study of some Cyclopentadiene Derivatives

Autori
Vianello, Robert ; Liebman, Joel F. ; Maksić, Zvonimir

Izvornik
Chemistry-A European Journal (0947-6539) 10 (2004); 5751-5761

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Bronsted superacids; neutral organic acids; aromaticity; cyclopentadiene; acidity

Sažetak
It is shown by using efficient but reasonably accurate B3LYP/6- 311+G(d, p)//B3LYP/6- 31G(d) procedure that pentasubstituted cyclopentadienes like (CN)5C5H, (NO2)5C5H and (NC)5C5H involving strong electron withdrawing groups are very good candidates for neutral organic superacids of unprecedented strength. All of them exhibit prototropic tautomerism by forming somewhat more stable structures possessing C=NH, NO2H and N=CH exocyclic fragments. Their acidity (DHacid) is thereby lower, but to a rather small extent, assuming values of 263.6, 269.6 and 275.3 kcal/mol, respectively. Hence, the most stable tautomers represent a legitimate target for synthetic chemists. The origin of a highly pronounced acidity of these compounds is analyzed by using the recently developed triadic (trichotomy) formula and it is identified as very high Koopmans' ionization potential (IP)nKoop of conjugate bases. Hence, the overwhelming influence on acidity is due to the properties of the final state.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA