Natural bond orbital (NBO) population analysis of para-substituted S-Nitroso-thiophenols

Abstract

Listen

Translate article

Theoretical study of several para-substituted S-Nitroso-thiophenols has been performed using quantum computational ab initio RHF and density functional B3LYP and B3PW91 methods with 6-31G(d,p) basis set. Geometries obtained from DFT calculations were used to perform NBO analysis. It is noted that the weakness in the S N sigma bond is due to n O 1 → σ S 3 N 2 ∗ delocalisation and is responsible for the longer S N bond length in para-substituted S-Nitroso-thiophenols. It is also noted that decreased occupancy of the localized σ SN orbital in the idealized Lewis structure, or increased occupancy of σ SN ∗ of the non-Lewis orbital, and their subsequent impact on molecular stability and geometry (bond lengths) are related with the resulting p character of the corresponding sulfur natural hybrid orbital (NHO) of σ SN bond orbital. In addition, the charge transfer energy decreases with the increasing of the Hammett constants of subsitutent groups and the partial charge distribution on the skeletal atoms shows that the electrostatic repulsion or attraction between atoms can give a significant contribution to the intra- and intermolecular interaction.