Fluorocarbonyl oxide: CASSCF/CASPT2 study of structure, cis effect and unimolecular decomposition paths

The electronic structure and unimolecular decomposition paths of fluorocarbonyl oxide were studied at the CASPT2/cc-pVTZ level utilizing the CASSCF/cc-pVTZ optimized geometries. The decomposition was followed up to the formation of the (fluoro)formyloxyl radical, carbon dioxide and hydrogen fluoride. The channels of direct decomposition of the structural isomer fluorodioxymethane to HF and CO2, as well as of fluoroformic acid to CO and HFO are absent due to the orbital and thermodynamic factors. The cis effect is studied recognized in connection with the two conformational isomers of fluorocarbonyl oxide. It was observed that the overwhelmingly favorable nuclear-electron attraction term may fully compensate for the sum of the unfavorable nuclear repulsion and two-electron terms in the cis isomer.