Table 1: Energies and geometries of both synchronous and synchronous [2 + 2] photocycloaddition reactions.

StructureEnergy/eVC1–C7C2–C8 C2–C1–C7–C8

(syn)03.493.6138.2
(asyn)0.073.223.42−23.6
FC (syn)4.98
FC (asyn)4.99
CI (syn)5.762.102.0615.2
CI (asyn)4.771.562.66−38.8