Chapter 14, Problem 14.10P

Interpretation Introduction

Interpretation:

The given molecule is to be identified as aromatic, antiaromatic, or nonaromatic assuming that the given molecule is entirely planar.

Concept introduction:

Huckel’s rule for aromaticity states that if a species possesses a pi system of molecular orbitals constructed from p-orbitals that are fully conjugated around a ring (${\text{sp}}^2$ hybridized), then the species is:

1) Aromatic if the number of electrons in that $\text{π}$- system is $2,6,10,14,18,\text{and so on}\text{.}$ (These numbers are called Huckel numbers.) 2) Antiaromatic if the number of electrons in that $\text{π}$- system is $4,8,12,16,20,\text{and so on}\text{.}$ (These numbers are called anti-Huckel numbers.) 3) All other species are considered nonaromatic. In other words, Huckel number is an odd number of pairs whereas anti-Huckel number is an even number of pairs. The Huckel number corresponds to $4\text{n}+2\text{π}$, where $\text{n}\ge 0$. Anti-Huckel number corresponds to $4\text{n}$ where $\text{n}\ge 1$.