Fig. 4: Potential-energy surface of the reaction.
From: Conformer-specific polar cycloaddition of dibromobutadiene with trapped propene ions

Simplified zero-point-corrected potential-energy profile of the electronic ground state of the [DBB-C3H6]+ system showing the most important structures along the minimum-energy paths for the polar cycloadditions of both conformers of DBB calculated using the M06-2X density functional and the def2-TZVPP basis set (Methods). A detailed PES containing additional conformational pathways and side-products is shown in Supplementary Fig. 5. Selected molecular orbitals that illustrate chemical bonds formed during the reaction are depicted for specific structures.