Designate whether each of the following compounds is aromati... | Chemistry - Hückel’s Rule | SolveeIt

Designate whether each of the following compounds is aromatic or not aromatic.

a, c, d, e, h aromatic and b, f, g not aromatic

b, e, f, g aromatic and a, c, d, h not aromatic

a, b, c, d aromatic and e, f, g, h not aromatic

e, g aromatic and a, b, c, d, f, h not aromatic

Answer

a, c, d, e, h aromatic and b, f, g not aromatic

Explanation

Aromaticity is determined by planarity, cyclic conjugation, and Hückel’s rule ( $4n+2$ π electrons).

(a) Cyclopentadienyl anion: 6 π electrons → aromatic.
(b) Cyclopentadienyl cation: 4 π electrons → antiaromatic → not aromatic.
(c) Cyclobutadiene dication (2 π electrons): meets Hückel’s $4n+2$ with $n=0$ → aromatic.
(d) Cyclobutadiene dianion (6 π electrons): planar 4‑membered with two lone pairs → aromatic.
(e) Cyclooctatetraenyl cation: 6 π electrons → aromatic.
(f) Neutral cyclooctatetraene: 8 π electrons, adopts nonplanar tub conformation → not aromatic.
(g) Cyclobutane: saturated ring, no continuous π system → not aromatic.
(h) Cyclopropenyl cation: 2 π electrons → aromatic.

Question: Designate whether each of the following compounds is aromatic or not aromatic....