find solution

1) (a) Describe the difference in the pi-electron population in the allyl cation and the allyl anion.

(b) What is the best way to draw the structure of the allyl cation?

2) (a) Describe aromaticity from a molecular orbital standpoint.

(b) Describe antiaromaticity from a molecular orbital standpoint.

3) (a) What is meant by the statement that cyclopropanes are magnetically anisotropic?

(b) Use molecular orbitals to explain why the protons in cyclopropane come into resonance in their NMR spectra at an unusually high field, typically 1 ppm upfield of the protons of an open-chain methylene (-CH2-) group.

4) Compare the lowering in energy of a bonding molecular orbital when it results from the interaction of two atomic orbitals of very similar energy to the energy lowering of a bonding molecular orbital when it results from the interaction of two atomic orbitals of unequal energy.

.5) Using Equation 1.12, or by drawing the geometrical equivalent, calculate the coefficients for the frontier orbitals of the heptatrienyl cation.

5) Spiro-aromaticity (Section 1.5.5) is barely detectable. Explain why the spiro cation 1.54, might have more T stabilisation by spiro conjugation than spiro- heptatriene 1.30