Figure 2. HOMO and LUMO of buta-1,3-diene and ethene (A); buta-1,3-dien-2-amine and nitroethene (B); and 2-nitrobuta-1,3-diene and ethenamine (C)

From

Teaching Thermodynamic, Geometric and Electronic Aspects of Diels-Alder Cycloadditions by Using Computational Chemistry – An Undergraduate Experiment

Norberto K. V. Monteiro, Caio L. Firme

World Journal of Chemical Education. 2015, 3(6), 141-149 doi:10.12691/wjce-3-6-3