Density functional theory studies on dioxygen difluoride and other fluorine/oxygen binary compounds: Availability and shortcoming

The hybrid DFT methods with 12 different basis sets were used for the computation of FOOF. Comparison with CCSD/6-311 + G* method was made. The availability and shortcoming of DFT methods for FOOF were pointed out. On that basis, the binary compounds of fluorine and oxygen (OnFm, n = 1-3, m = 1-2) were calculated at the G96PW91/D95(3df) level. The affiliation of lone pair electrons toward the fluorine atom decreases from OF2 to O3F2 as the number of oxygen increases. The strength of O-O bond decreases from O2F2 to O3F2. The shorter O-F bond of O3F2 could readily change to longer one and vice versa through a transition state with energy barrier of 11.06 kJ/mol. The O-F bond is much stronger than the O-O bond in O3F2. On the contrary, the O-F bond is much weaker than the O-O bond in O2F2. O2F and O3F can be regarded as weakly bound OO-F and OO-OF adducts, respectively. O3F2 could be regarded as a weakly bound FO-OOF adduct. The standard enthalpies and free energies of formation for the binary compounds were predicted at both the G96PW91 and the G2 levels.