Topomerization of 2-Halo-[9] Annulen Anion at the DFT Level

Topomerization of 9] annulen anion(1)and its 2-fluoro-,2-chloro-and 2-bromo-derivatives(2,3 and 4,respectively)are studied at the HF/6-31G* and B3LYP/6-311++G** levels of theory.The relative ease of topomerization is dependent on the charge distribution and planarity of the ground state and the transition state of 9-membered rings as well as the size and electronegativity of halogen substituent.Consequently,the endo-2-halo-9] annulen anion topomers become unstable and easily convert to related exo-topomer...