An ab initio quantum-chemical study of C6H5SO2CH3 and C6H5SO2CF3 in the MP2(full)/6-31+G* approximation with NBO analysis of wave functions

Potential functions of internal rotation around \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$C_{sp^2 } - S$$ \end{document} bonds in C6H5SO2Ch3 (I) and C6H5SO2CF3 (II) were obtained by ab initio MP2(full)/6-31+G* calculations. The revealed stationary points were identified by solving vibration problems. In the energetically favorable conformations of I and II, the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$C_{sp^2 } - S - C_{sp^3 } $$ \end{document} plane is perpendicular to the benzene ring plane. The barriers to rotation around the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$C_{sp^2 } - S$$ \end{document} bonds in I and II are 20.81 and 28.23 kJ mol−1, respectively. The parameters of the molecular geometry were estimated. The wave functions were analyzed using the NBO formalism, and the distribution of natural charges over atoms was considered.