Uma comprovação químico-quântica sobre a formação de ligações de hidrogênio e interações secundárias em sistemas heterocíclicos intermoleculares

Abstract

We have performed a detailed theoretical study in order to understand the charge density topology of the C2H4O···C2H2 and C2H4S···C2H2 heterocyclic hydrogen-bonded complexes. Through the calculations derived from Quantum Theory of Atoms in Molecules (QTAIM), it was observed the formation of hydrogen bonds and secondary interactions. Such analysis was performed through the determination of optimized geometries at B3LYP/6-31G(d,p) level of theory, by which is that QTAIM topological operators were computed, such as the electronic density ρ(r), Laplacian ∇ 2ρ(r), and ellipticity ε. The examination of the hydrogen bonds has been performed through the measurement of ρ(r), ∇ 2ρ(r) and ε between (O···H—C and (S···H—C), whereas the secondary interaction between axial hydrogen atoms Hα and carbon of acetylene. In this insight, it was verified the existence of secondary interaction only in C2H4S···C2H2 complex because its structure is propitious to form multiple interactions.