The C-H<middle dot><middle dot><middle dot>S-S hydrogen bonding in diethyl disulfide⋯difluoromethane: a combined microwave spectroscopic and computational study

The C-H & ctdot;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 & ctdot;S-S interaction. The most stable conformation observed experimentally is stabilized by one C-H & ctdot;S-S hydrogen bond and two weaker C-H & ctdot;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 & ctdot;F and H & ctdot;S distances of 2.68(7) & Aring; and 2.64(1) & Aring;, respectively, with bonding angles of 121.0(4)degrees for C-H & ctdot;F and 135.3(6)degrees for C-H & ctdot;S hydrogen bonds. The geometric characteristics and theoretical analyses suggest that the C-H & ctdot;S-S hydrogen bond is the predominant interaction, contributing an energy of 7.6 kJ mol-1. Additionally, the C-H & ctdot;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.