Molecular orbitals studies on two limiting structures of conjugated vinyl cation,C4H4F+

Nonempirical LCAO-MO-SCF calculations employing STO-3G minimal basis set have been carried out to examine the two limiting, open and bridged, structures of a conjugative fluorovinyl cation system and the interconversion of these two structures. The bridged ion is found to be 37.6 kcal/mole higher in energy than the open ion. Three pathways of converting the open ion to bridged ion were investigated. The pathway in which conjugation is preserved along the reaction profile gives the lowest energy barrier and depicts the bridged ion as a transition state.