Question

How many of the following given molecules are aromatic in nature

Answer 1

(a) Anti-aromatic, $4\pi e^{-}$ system, all atoms are $s{p}^2$ hybridised.
(b) Aromatic, $6\pi e^{-}$ system, all atoms are $s{p}^2$ hybridised (consider only 1 lone pair of O).
(c) Aromatic, $6\pi e^{-}$ system, all atoms are $s{p}^2$ hybridised.
(d) Aromatic, $6\pi e^{-}$ system, all atoms are $s{p}^2$ hybridised (consider only 1 lone pair of N).
(e) Non-aromatic, $12\pi e^{-}$ system but non-aromatic due to lack of planarity in the structure.
(f) Aromatic, $6\pi e^{-}$ system, all atoms are $s{p}^2$ hybridised.
(g) Aromatic, $10\pi e^{-}$ system, methylene bridge gives the planar bicyclic 1,6-methano[10]annulene.
(h) Aromatic, $2\pi e^{-}$ system, all atoms are $s{p}^2$ hybridised.
(i) Non-aromatic, non planar, $10\pi e^{-}$ system but non aromatic due to the two trans hydrogens non bonded repulsions making the molecule non planar.
(j) Non-aromatic, non planar, tub like shape, $8\pi e^{-}$ system.