Theoretical Study on Potential Energy Surface of the C2H2FO Radical

The potential energy surface of C 2 H 2 FO is investigated at CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p) level. The results show that isomers of 1, 3, 4, 5, 5‘, 8, 9, and 9‘ are stable, and the energy barriers are more than 30 kcal/mol. Isomer 2 has, relatively speaking, much lower kinetic stability. The three cyclic isomers 6, 6‘, and 7 are less stable than the former, but more stable than the latter. The other isomers, such as isomers 1‘, 3‘, 4‘, 10, and 11 are less stable than isomer 2 in kinetics. Only isomer 1 was synthesized experimentally, and the calculated frequencies are in good agreement with experimental values, so we conjecture that in the future, other stable isomers may be synthesized by the experimental methods, for example, coming from such reactions as FCCH + OH, CH 2 F + CO, and so forth. Compared to the analogous C 2 H 3 O radical isomers, the energy order is changed. This may be due to conjugation of the carbonyl group in isomer 1 CH 2 CFO with the substituent fluorine at the α-position.