Interaction of p orbitals in polyenes at the Huckel level of theory butadiene methyl allyl ethene Energy eV Stabilization energy eV 12.3 14.5 24.8
2 x 2 x Stabilization Energy 2x (-11.4 eV) 2x (-17.6 eV) Energy of electon on isolated p orbital 2 x 2x (-11.4 eV) 2 x Energy of electon on p orbital of ethylene 2x (-17.6 eV) Stabilization energy 2 x 6.2 = 12.4 eV
Electronic excitation and UV Absorption spectra butadiene hv butadiene * ethene ethene * hv DE = 17.1 eV DE = 11.4 eV exp 174 nm exp 216 nm