The C–H···S–S hydrogen bonding in diethyl disulfide⋯difluoromethane: a combined microwave spectroscopic and computational study

Abstract

The C–H⋯S weak interaction is crucial for comprehending the stability in biological macromolecules and their interactions with smaller molecules. Despite its prevalence, an in-depth understanding and recognition of such interaction remain elusive. Herein, the rotational spectra of a binary complex formed by diethyl disulfide and difluoromethane were investigated using Fourier transform microwave spectroscopy combined with theoretical calculations to examine the C–H⋯S–S interaction. The most stable conformation observed experimentally is stabilized by one C–H⋯S–S hydrogen bond and two weaker C–H⋯F hydrogen bonds. Non-covalent interaction, natural bond orbital, and symmetry-adapted perturbation theory methods were employed to describe the intermolecular interactions within the adduct. Experiments indicated H⋯F and H⋯S distances of 2.68(7) Å and 2.64(1) Å, respectively, with bonding angles of 121.0(4)° for C–H⋯F and 135.3(6)° for C–H⋯S hydrogen bonds. The geometric characteristics and theoretical analyses suggest that the C–H⋯S–S hydrogen bond is the predominant interaction, contributing an energy of 7.6 kJ mol⁻¹. Additionally, the C–H⋯F hydrogen bond also contributes to the stability of the complex, contributing approximately 2.6 kJ mol⁻¹. London dispersion is a primary factor in the stability of complexes, contributing 53% to the total attractive interaction. The results indicate that non-traditional hydrogen bond participants, such as C–H groups and S–S linkages, can form hydrogen bonds and fluorination enhances the interactions.