Insight into the nature of the noncovalent interactions of furan, pyridine, and pyrazine with AtX

Context The σ-hole, counterintuitive σ-hole, and lone pair-π interaction complexes formed between three heterocyclic compounds (C4H4O, C5H5N, and C4H4N2) and AtX (X = F, Cl, and Br) have been investigated with the MP2/aug-cc-pVTZ. The intensity of three noncovalent interactions formed by different heterocyclic compounds was compared, and the properties of these three noncovalent interactions were discussed. SAPT analysis shows that the electrostatic energy is dominant to the stronger interactions in the σ-hole and counterintuitive σ-hole complexes, while the dispersion energy is the main force responsible for the weaker interactions in the lone pair-π complexes. NBO analysis has also been employed. Methods All the structures were optimized at the MP2/aug-cc-pVTZ (aug-cc-pVTZ-pp for Br to account for relativistic effects) level using the Gaussian 03W package (Gaussian, Inc., Wallingford, CT, USA). The basis bet superposition error (BSSE) is corrected using counterpoise method proposed by Boys and Bernardi. The NBO population analysis was carried out. The molecular electrostatic surface potentials of monomers were calculated by WFA-SAS program package. The interaction energies of the three types complexes were decomposed by using the symmetric adaptive perturbation theory SAPT of the open source ab initio electronic structure software package psi 4.0.0-beta5.