LAUSR

Abstract The strengths of π-bonds in a series of fluorinated ethylenes have been computationally investigated, and the potential energy surfaces for thermal C C bond rotation in fluorinated ethylenes, as well as in ethylene, have been explored. The computed thermal rotational barrier values and the π-bond strengths obtained using Benson’s procedure show parallel trends. Our calculations indicate that the π-bond in CH2 = CHF is slightly stronger, and the one in CF2 = CF2 is noticeably weaker than that in CH2 = CH2. In addition, the stabilization effects of fluorine substitution have been evaluated for fluorinated ethylene molecules and for singlet biradical thermal rotation transition states. Considering these fluorine substituent effects, the change in the π-bond strength of a series of fluorinated ethylenes can be qualitatively interpreted.