7-Bromo-1,3,5-cycloheptatriene exists as an ion whereas 5-bromo-1,3-cyclopentadiene does not form an ion even in presence of Ag^+. Explain

7-Bromo-1,3,5-cycloheptatriene exists as an ion whereas 5-bromo-1,3-cy

1.	7-Bromo-1,3,5-cycloheptatriene exists as an ion whereas 5-bromo-1,3-cyclopentadiene does not form an ion even in presence of Ag^+. Explain
Answer» <html><body><p></p>Solution :7-Bromo-1,3,5-cycloheptatriene, on ionization, gives tropylium ion. Since , tropylium ion contains `6 <a href="https://interviewquestions.tuteehub.com/tag/pi-600185" style="font-weight:bold;" target="_blank" title="Click to know more about PI">PI</a>`-electrons which are completely delocalized, therefore, according to Huckel rule, it is <a href="https://interviewquestions.tuteehub.com/tag/aromatic-363924" style="font-weight:bold;" target="_blank" title="Click to know more about AROMATIC">AROMATIC</a> and <a href="https://interviewquestions.tuteehub.com/tag/hence-484344" style="font-weight:bold;" target="_blank" title="Click to know more about HENCE">HENCE</a> stable .Being highly stable , it is easily <a href="https://interviewquestions.tuteehub.com/tag/formed-464209" style="font-weight:bold;" target="_blank" title="Click to know more about FORMED">FORMED</a> . <br/> <img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/PR_CHE_02_XI_C13_E19_002_S01.png" width="80%"/> <br/> In contrast,5-bromo-1,3-cyclopentadiene, on ionization, will give 1,3-cyclopentadienyl cation which contains `4pi`-electrons and hence in antiaromatic. Being antiaromatic, it is highly unstable and hence is not formed even in the presence of `Ag^+` ion which otherwise facilitates ionization.</body></html>