Question
Explain why the following systems are not aromatic?
Solution
Since the above structure contains sp3 hybridised carbon, therefore the system is not planar. Though it can six
electrons yet the system is not fully conjugated. In other words, all the six 
-electrons do not form a single cyclic electron cloud which surrounds all the atoms of the ring. Hence it is not an aromatic compound. 
The system is not planar due to the presence of sp3 hybridised carbon. Also,it contains four electrons, indicating that the system is not aromatic i.e. the system does not obey (4n + 2)n-electrons.
The system is not planar but has a tub-like a shape. It is, therefore, a non-planar system having
. Hence the molecule is not aromatic since it does not obey (4n+2) 
.
