Resumo

OLIVEIRA, B. G.. A DFT and AIM study of blue-shifting hydrogen bonds and secondary interactions in small heterocyclic complexes. J. Argent. Chem. Soc. [online]. 2007, vol.95, n.1-2, pp.59-69. ISSN 1852-1428.

In this work, a computational study of molecular properties of small heterocyclic intermolecular systems is presented. Fundamentally, the B3LYP/6-31G(d,p) and B3LYP/6-311++G(d,p) theoretical methods were used to determine the optimized geometries of the C₂H₄O···HCF₃ and C₄H₆O···HCF₃ heterocyclic complexes and thereby evaluate the existence of blue-shifting hydrogen bonds on these systems. A contraction of the C-H bond length of the fluoroform (HCF₃) was observed by analyzing the main structural parameters. Consequently, results of infrared spectrum analysis showed the blue-shift in the stretch frequency accompanied by a significant decrease in absorption intensity. With the purpose of comprehending this vibrational phenomenon, hybrid functional and split valence basis sets were used and topological parameters derived from Atoms-in-Molecules (AIM) theory were also applied. Moreover, the non-linear deviation in (O···H) anti-hydrogen bonds due to the secondary interaction (H^a···F^j) between the fluorine (F^j) of fluoroform and axial hydrogen atoms (H^a) of the heterocyclic structures was verified.

Palavras-chave : DFT; Blue-shifting; Hydrogen bond; Heterocyclic complexes.