but to but...
OK, continuos cojugation involve sp2 hybridization.. Let's analyse :
a: 6 pi electrons (=4x1+2)
b: 2 pi electrons (=4x0+2)
c: 4 pi electrons (non aromatic)
d: 6 pi electrons
e: 6 pi electrons
For the d structure: we have 6 pi electrons in the benzene ring. The missing electron is from the sp2 orbital and is not participate to the continuos conjugation. In my opinion, such a cation is not stable and that is just a theoretical problem. More on the problem of aromaticity you will find working on Huckel equations.
|