S⋯N chalcogen bonded complexes of carbon disulfide with diazines. Theoretical study

Abstract

Carbon disulfide complexes with diazine (pyridazine, pyrimidine or pyrazine) have been studied by density functional BLYP-D3 and ab initio CCSD(T) methods. All possible conformers of these complexes have been found. In the chalcogen bonded complexes, the CCSD(T)/cc-pvtz calculated interaction energies (ΔE) range between −0.89 and −2.19 kcal mol−1. These complexes are more stable than those stabilized by hydrogen bond. The linear correlation between the ΔE and the most negative values of the electrostatic potential surfaces (Vs,min) on the nitrogen atom of the diazines has been found. According to the symmetry-adapted perturbation theory (SAPT) analysis, in the chalcogen bonded complexes among all of the attraction forces the electrostatic component is the most important one, while in the hydrogen bonded and stacking complexes the dispersion contribution is the leading term. Moreover, the Natural Bond Orbitals (NBO), AIM and Noncovalent Interaction Index (NCI) analyses have been performed.