Topological analysis of the electron localization function applied to the study of the [1,3] sigmatropic shift of fluorine in 3-fluorpropene

The [1,3] sigmatropic shift of the fluorine atom in the 3-fluorpropene syst em has been studied from the topological analysis of the electron localizat ion function (ELF). All calculations have been carried out at the B3PW91/6- 311g** level of theory. The allowed suprafacial pathway through a concerted four-membered C-s transition state (TS) has been characterized in terms of an ion pair structure which shows the halogen atom bearing -0.6e. The ioni c nature of the TS is supported by the absence of any polisynaptic basin co nnecting the fluorine and the allyl fragments in this stationary point. Fin ally, the evolution of the bonding characteristics along the intrinsic reac tion coordinate reaction path has been analyzed in detail in terms of the b asin properties of the ELF function. (C) 2001 American Institute of Physics .