Which of the following would you expect to be antiaromatic?

Question

Quizplus · Accepted Answer

A molecule is antiaromatic if it has a planar ring with 4n π electrons (where n is an integer). In option III, the cyclooctatetraene ring has 8 π electrons, which is 4n, where n=2. Therefore, it is antiaromatic. The other options do not have planar rings with 4n π electrons. Option I has a non-planar structure, option II has a planar ring with 6 π electrons (which is not 4n), options IV and V have planar rings with 10 π electrons, which is 4n+2 (where n=2 in each case), and therefore, they are not antiaromatic as per Hückel's rule.

Which of the Following Would You Expect to Be Antiaromatic