DIFFERENT APPROACHES FOR THE THEORETHICAL TREATMENT OF ANIONS WITH CONVENTIONAL METHODS

PUIATTI, MARCELO; D. MARIANO A: VERA; ADRIANA B. PIERINI

Florianópolis, Brasil

Conferencia; Latin American Conference in Physical Organic Chemistry; 2009

Profesor Fauk Nome, Univeridad de Florianópolis. Comitee LatinoAmericano

Here in we present an evaluation of this method for the calculation of the EA of temporary anions. In addition, we will also explore the possibility for finding the V state as one of the excited states of the N anions, by using the TD-DFT approach. Its actual feasibility in determining very unstable anion states is an open question, which is worth to address, since the stabilization by any means seems to be harder to obtain, the more negative the EA is. TD-DFT would also offer the opportunity of calculating higher vertical EAs apart from the first one, corresponding to the ground anion. These approaches were evaluated by calculating 60 compounds including DNA bases, halogenated, aromatic and cyclic compounds, with different functionals and basis sets. For the first methodology the best results were obtained with the IEFPCM solvent, at the B3LYP/6-311+G(2df,p) level of theory with a correlation with experimental values of EAExp= (1.01 EAcalc+ 0.06)  0.06 eV. For the second alternative the best results were obtained with the PBE0 functional and a correlation of EAExp= (1.04 EAcalc+ 0.05)  0.21 eV.