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9564 J. Am. Chem. SOC.1995,117, 9564-9569 Ab Initio Study on the Unimolecular Decomposition

Summary: 9564 J. Am. Chem. SOC.1995,117, 9564-9569
Ab Initio Study on the Unimolecular Decomposition
Mechanisms and Spectroscopic Properties of CH30F
Yitzhak Apeloig* and Karsten Albrecht
Contribution from the Department of Chemistry, Technion-Israel Institute of Technology,
Technion City, 32000 Haifa, Israel
Received March 27, 1995@
Abstract: 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 correlationis 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 CH20 and HF, were studied. Of these,
two mechanisms,the synchronoussingle-stepHF eliminationand a two-stepmechanism via the CH30' and Fradicals,
are predicted to be the most favorable, both having activation free energies of ca. 38 kcal mol-' 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.
Hypofluorites (ROF) are usually kinetically unstable com-
pounds, and the only molecules of this type that persist for a
long time at ambient temperatures are ones in which the 0-F
unit is bonded either directly to another fluorine atom (OF$ or


Source: Apeloig, Yitzhak - Department of Chemistry, Technion, Israel Institute of Technology


Collections: Chemistry