Supramolecular Structure of Sulfonamide-Substituted Silatranes: Quantum Chemical DFT Calculations

The supramolecular structure of the crystal products-N-[2-chloro-2-(silatranyl)ethyl]-4-nitro-benzenesulfonamide 4d and N-chloro-N-[2-chloro-1-(silatran-1-yl-methyl)ethyl]benzene-sulfonamide 5a was established by X-ray diffraction analysis data, FTIR spectroscopy and DFT quantum chemical calculations. Their crystal lattice is formed by cyclic dimers with intermolecular hydrogen NH∙∙∙O-Si bonds and CH∙∙∙O=S short contacts. The distribution of electron density in the monomers was determined using quantum chemical calculations of their molecular electrostatic potential (MESP) in an isolated state (in gas) and in a polar medium. The transition from covalent N-Si bonds in crystal compounds and polar medium to non-covalent N∙∙∙Si bonds happened while performing the calculations on the monomer molecules and their dimers in gas. The effect of intermolecular interactions on the strength of the N-Si and N∙∙∙Si bonds in molecules was evaluated through calculations of their complexes with H₂O and DMSO.