Chapter 5, Problem 5.60SP

Interpretation Introduction

Interpretation:

The p orbitals present in given allyl cation should be sketched and the bonding should be described using the valence bond model for $\sigma$ bonding and delocalized $MO$ model for $\pi$ bonding.

Concept Introduction:

Sigma (σ) bonds: The bonds in which shared hybrid orbital’s electron density are concentrated along the internuclear axis and it is represented as the single bond between atoms in molecules.

Pi (π) bonds: the bonds in which shared unhybridized orbital’s (p, d, etc) electron density are concentrated in above and below of the plane of the molecule.

Double bonds: One sigma bond and one pi bond are together known as a double bond.

Molecular orbital theory:

The atomic orbitals of the atoms constituted in a molecule are combined to produce new orbitals are called Molecular Orbitals.

Like atomic orbitals, a molecular orbital can accommodate maximum two electrons and the two electrons must have opposite spins (Pauli Exclusion Principle).

The numbers of MO’s are equals to the number of atomic orbitals are combined in such a way that the linear combination of similar atomic orbitals to form one bonding and one anti-bonding MO’s.

The bonding MO’s are lower in energy than the anti-bonding MO’s.

HOMO is the highest energized occupied orbital in the MO’s.

Relative energy levels of molecules are according to the energy levels of atomic orbitals.

LUMO is the lowest energized orbital in the MO’s.