Ab initio study on the unimolecular decomposition mechanisms and spectroscopic properties of CH3OF

Article abstract of DOI:10.1021/ja00142a027

High-level ab initio calculations of the structure, vibrational frequencies, and NMR spectra of the recently isolated methyl hypofluorite, CH₃OF, have been carried out. When electron correlation is included in the calculations (but not at the HF level), there is a very good agreement between the experimental and the theoretical IR and NMR spectra. Four different unimolecular decomposition pathways, all leading to CH₂O and HF, were studied. Of these, two mechanisms, the synchronous single-step HF elimination and a two-step mechanism via the CH₃O^? and F^? radicals, are predicted to be the most favorable, both having activation free energies of ca. 38 kcal mol^-1 at GAUSSIAN 2. A theoretical analysis of the expected kinetic isotope effects between the competing pathways leads to a clear differentiation which can be used in experimental studies.