QTAIM Densities and Ab Initio Basis Sets: A Chemometrical Analysis of the Intermolecular Electronic Densities of the Hydrogen-Bonded Complexes C₂H₄O···HX (X = F, CN, NC, and CCH)

Boaz Galdino de Oliveira,^1,* Regiane de Cássia Maritan Ugulino de Araújo,¹ Antônio Bezerra de Carvalho¹ and Mozart Neves Ramos²

¹ Departamento de Ciências Farmacêuticas, Universidade Federal de Pernambuco 50740-521, Recife, Pernambuco – Brazil
² Departamento de Química Fundamental, Universidade Federal de Pernambuco 50739-901, Recife, Pernambuco – Brazil

* Corresponding author: E-mail: boazgaldino@gmail.com

Abstract
The intermolecular electronic densities of the hydrogen-bonded complexes C₂H₄O···HX (X = F, CN, NC, and CCH) were determined by calculations performed at the level of Density Functional Theory (DFT). The B3LYP functional and the Pople’s 6-31G split-valence basis set were combined with (11) valence, (++) diffuse and (d,p) polarization functions with the purpose to determine the optimized geometries of the C₂H₄O···HX complexes. Through these geometries, their intermolecular electronic densities ρ(r,x)^QTAIM calculated from Quantum Theory of Atoms in Molecules (QTAIM) were examined through the Hierarchical Cluster Analysis (HCA) and Two-Level Factorial Designs (TLFD) statistical techniques. Although it is well-known that the QTAIM approach was projected with a slight dependence from ab initio basis sets, our results revealed a good relationship between ρˉ (r,x)^QTAIM and the values estimated by the chemometric analysis ( ρ(r,x)^EST) computed essentially by valence (11) and diffuse (++) functions.

Keywords: QTAIM; basis sets; B3LYP; hydrogen complexes