Number of anti-aromatic compound in the following compound is _____.

 

The molecules, which have 4n$\mathrm{\pi }$ electrons are anti-aromatic compounds

a) has 4$\mathrm{\pi }$-electrons

(b) has 6 + 2 (from oxygen atom) - 8$\mathrm{\pi }$ electrons

(c) has 6$\mathrm{\pi }$-electrons and one C-atom is sp3 hybridised hence it is non - aromatic

(d) is aromatic

(e) has 4$\mathrm{\pi }$-electrons as available lone pair with N - atom will not be delocalized in this conjugated system.

(f) has 12$\mathrm{\pi }$-electrons. 

Hence, (a), (b), (e) and (f) are anti-aromatic.