Chapter 12.20, Problem 28P

Interpretation Introduction

Interpretation:

Whether the given ions are aromatic or antiaromatic is to be identified.

Concept introduction:

Molecules, to be an aromatic, must obey Hückel’s rule of $\text{(4n+2)π}$ electrons where $\text{n}$ is an integer.

Aromatic molecules are cyclic and planar and have cyclic conjugation.

Antiaromatic molecules are planar and have cyclic conjugation like aromatic molecules, but they have $\text{(4n)π}$ electrons instead $\text{(4n+2)π}$ electrons.

Each double bond contributes two $\text{π}$ electrons. The carbon with negative charge contributes two $\text{π}$ electrons, and the carbon with positive charge does not contribute any.