The CNDO/2 Study of Barbararyl Cation and Its Isomeric C9H9+ Systems

Abstract
The geometrical and electronic structures of C9H9+ systems have been studied applying CNDO-2 method. The calculated results are used to discuss the stabilities of the structures for C9H9+ system and their electronic states. It is suggested that the carbonium ion which has a D3h symmetry (IV) enjoys much stabilization energy, whereas bicyclo[3.2.2]nonatrienyl cation (I) is less stable than IV. The stability of IV can be explained by unusual delocalization of its electrons over the molecule.