Answer to Question #239463 in Organic Chemistry for merewalesi

Question

(c) The reaction of allylic bromide (I) with magnesium metal generates the Grignard reagent (II) as shown below. Reagent II can be viewed as an ionic compound, consisting of components III and MgBr+.
Explain why structure I is not aromatic and draw molecular orbital diagram for species III and show how these molecular orbitals are occupied in the ground state of the species. Is the configuration a closed shell configuration? Explain.

Answer 1

For the given compound, the number of π-electrons is six. But only four π-electrons are present within the ring. Also there is no conjugation of π-electrons within the ring and the compound is not planar in shape. Hence, the given compound is not aromatic in nature.

The configuration is a closed shell