Choose the answer that has the molecular orbitals of the allyl anion (CH₂=CH-CH₂⁻) correctly identified. The three pi molecular orbitals are drawn below (shaded and unshaded lobes show opposite phase).
(I)
(II)
(III)

Question

Choose the answer that has the molecular orbitals of the allyl anion (CH₂=CH-CH₂⁻) correctly identified. The three pi molecular orbitals are drawn below (shaded and unshaded lobes show opposite phase).

(I) structure

(II) structure

(III) structure

TestHub · Accepted Answer

Allyl anion has 4 pi electrons. The lowest orbital (I, no node, all lobes in phase) is bonding. The second orbital (II, one node through the central carbon) is the non-bonding orbital and holds the last two electrons, so it is the HOMO. The orbital with two nodes (III) is empty, so it is the LUMO.

Answer : (I) bonding, (II) HOMO, (III) LUMO.

Chemistry - GOC Question with Solution | TestHub

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