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 = 1-3, m = 1-2) were calculated at the G96PW91/D95(3df) level. The affiliation of tone 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. (c) 2006 Elsevier B.V. All rights reserved.