Chapter 6, Problem 64P

For each of the following molecules, construct the $\pi$ MOs from the $2p_z$ atomic orbitals perpendicular to the plane of the carbon atoms.

(a) Cyclobutadiene HC

(b) Allyl radical

Indicate which, if any, of these orbitals have identical energies from symmetry considerations. Show the number of electrons occupying each $\pi$ MO in the ground state, and indicate whether either or both of the molecules are paramagnetic. Assume that the C atoms in the allyl radical are all $s{p}^{\text{2}}$ hybridized.