High level ab initio thermochemistry of SF5OOO radical

Publication date: Available online 16 December 2018Source: Computational and Theoretical ChemistryAuthor(s): Jessica Andrea Martínez Bernal, Gilles Pieffet, Vaneza Paola Lorett Velásquez, Cristian Buendía-AtencioAbstractThe molecular structure, vibrational frequencies, and enthalpy of formation of SF5OOO radical have been examined using several functionals such as pure GGA, hybrid GGA, meta-GGA, and “double hybrid” from density functional theory (DFT). The results show the existence of three conformations with symmetries Cs′, Cs and C1 for the SF5OOO radical, each differing in the spatial distribution and interactions of the oxygen atoms. All the functionals used in this study were capable of predicting the experimental vibrational frequencies, albeit with small differences in some of the vibrational bands. The thermochemistry studies were carried out with high-level Gn theories (G3MP2B3, G3B3, G4MP2 and G4), which provided reliable enthalpies of formation of -218.3 ±1.3, -217.2 ±1.6, and -218.0 ±1.5 kcal mol-1 for SF5OOO (Cs), SF5OOO (Cs′) and SF5OOO (C1) at 298 K. The relative stability of the three conformations was found to be almost identical with interconversion barriers at 0 K less than lower 1 kcal mol-1. Finally, application of bond additivity corrections (BAC) to the G3MP2B3 and G3B3 methods made the enthalpy of formation converge to the values obtained with the G4MP2 and G4 methods.Graphical abstractHigh level ab initio thermochemistry of SF5OOO radic...

Source: Computational and Theoretical Chemistry - December 16, 2018 Category: Chemistry Source Type: research