Chapter 17, Problem 17.19P

Interpretation Introduction

Interpretation: Among the given ions, aromatic rings are to be determined.

Concept introduction: A molecule must be cyclic, planar, completely conjugated and should follow Huckel’s rule to be classified as aromatic. For an antiaromatic molecule, the molecule must be cyclic, planar, completely conjugated and have $4n\pi$ electrons. For a non-aromatic molecule, the molecule lacks the one of the requirements to be aromatic or anti aromatic molecule.

According to the Huckel’s rule the number of $\pi$ electrons in the molecule must be equal to $\left(4n+2\right)$.