NBO analysis of halogen bridging in 4-halo-1-buten-3-yl cations

The major stabilizing orbital interactions in 4-halo-1-buten-3-yl cations were evaluated by Natural Bond Orbital methodology. Energetics of interactions of halogen lone pairs and bonds with allylic cationic centers for bromine, chlorine and fluorine revealed that hyperconjugative interactions were the major factor in controlling conformer stabilities.