Fluorofluoroxydioxirane and Other CF2O3 Isomers

Seven structural isomers, and relevant transition states, on the lowest-energy spin-singlet potential energy surface of CF 2 O 3 are characterized using correlated ab initio electronic structure methods. On the basis of preliminary comparative calculations, second-order Møller−Plesset perturbation theory with a correlation-consistent polarized valence double-ζ one-electron basis set (MP2/cc-pVDZ) was chosen with which to describe equilibrium structures and harmonic vibrational frequencies of all relevant rotamers. Accurate energy differences were determined using the coupled cluster method, with perturbative inclusion of triple excitations, and a valence triple-ζ basis (CCSD(T)/cc-pVTZ). The lowest energy isomer is predicted to be the molozonide of difluorocarbene, whose adiabatic decay is prevented by a sizable barrier. Plausible mechanisms for the isomerization of the titled compound to the low-energy fluoroformyl peroxyhypofluorite and nearly isenergetic carbonyl hypofluorite are suggested. An analogous reaction path may be of importance to the isomerization of difluorodioxirane (CF 2 O 2 ) and is included in the study.