Tetrel Bonds between Phenyltrifluorosilane and Dimethyl Sulfoxide: Influence of Basis Sets, Substitution and Competition.

Ab initio calculations have been performed for the complexes of DMSO and phenyltrifluorosilane (PTS) and its derivatives with a substituent of NH, OCH, CH, OH, F, CHO, CN, NO, and SOH. It is necessary to use sufficiently flexible basis sets, such as aug'-cc-pVTZ, to get reliable results for the Si···O tetrel bonds. The tetrel bond in these complexes has been characterized in views of geometries, interaction energies, orbital interactions and topological parameters. The electron-donating group in PTS weakens this interaction and the electron-withdrawing group prominently strengthens it to the point where it exceeds that of the majority of hydrogen bonds. The largest interaction energy occurs in the -HOS-PhSiF···DMSO complex, amounting to -122 kJ/mol. The strong Si···O tetrel bond depends to a large extent on the charge transfer from the O lone pair into the empty orbital of Si, although it has a dominant electrostatic character. For the PTS derivatives of NH, OH, CHO and NO, the hydrogen bonded complex is favorable to the tetrel bonded complex for the NH and OH derivatives, while the σ-hole interaction prefers the π-hole interaction for the CHO and NO derivatives.