Composite Methods and DFT Investigations of the Structures, Vibrational Frequencies and Energies of SF5OOX (X=H, F and Cl) and their Anions

A complete characterization of the vibrational modes has been performed for neutral and anionic pentafluorosulfur peroxides SF5OOX (X=H, F, and Cl) structures using density functional theory (DFT). The adiabatic electron affinity, bond dissociation energy and heat of formation of neutral pentafluorosulfur peroxides molecules were calculated using several Gn methods, starting from geometries optimized with B3LYP, M06-2X and MP2 levels of theory. The most accurate enthalpies at 298 K for SF5OOH, SF5OOF, and SF5OOCl are obtained with the G4 level of theory and were used as a reference. S-F and S-Cl bonds present low energy of dissociation compared to the S-H bond. This makes possible a dissociative electron attachment (DEA) of the S-X bond (with X=F, Cl) represented by the SF5OO-X + e- -> SF5OO- + X- reaction, while a S-H dissociation presents a low probability. This work provides crucial energetic data to improve the chemical information and characterization of these structures previously obtained through experimental studies.