When benzene is protonated the resulting ion is the cyclohexadienyl cation. Which of the following MOs is the best representation of the LUMO of this cation ?
⟶(H⁺)

Question

When benzene is protonated the resulting ion is the cyclohexadienyl cation. Which of the following MOs is the best representation of the LUMO of this cation ? ⟶ (H⁺)

TestHub · Accepted Answer

The cyclohexadienyl cation has a pentadienyl pi system (5 carbons, 4 electrons). Its two filled MOs are the two lowest. The LUMO is the third MO, the non-bonding one, which has two nodes passing through atoms 2 and 4 so that only carbons 1, 3 and 5 carry lobes, with phases +, -, +.

Only option (D) has this pattern.

Chemistry - GOC Question with Solution | TestHub

Options:

Doubts & Discussion