Figure8.2 the structure of a secondary vinylic carbocation The cationic carbon atom is sp-hybridized and has a vacant p orbital perpendicular to the plane of the € bond orbitals.Only one R group is attached to the positives charged carbon rather than two, as a secondary alkyl carbocation. The electrostatic potential map shows that most positive (blue) regions coincide with lobes of the vacant p orbital and are perpendicular to the most negative(red) regions associated with the $ bond