To achieve thermal equilibrium, CDCl3 solutions of the compounds were heated at 55 °C. The equilibrium ratios of the isomers were determined by H NMR spectroscopy (Figures and), and the results are summarized in Table . For 1O, the ratio of ZZ, EZ, and EE isomers (16:64:20) approached the statistical distribution (1:2:1), suggesting minimal differences in Gibbs free energy among the three geometric isomers. In contrast, 1S showed a marked preference for the Z-configuration with a ZZ:EZ:EE ratio of 58:35:6. We further investigated the temperature dependence of the isomer ratios to construct van't Hoff plots. By changing the solvent to [D2] tetrachloroethane, 1 H NMR measurements for 1S were performed over a temperature range of 60-100°C. The results revealing a gradual decrease in the ZZ isomer content, with a concurrent increase in the EE isomer content as the temperature increased (Figure ). The thermodynamic parameters obtained via a van't Hoff analysis at three different temperatures (Figure ) are summarized in Table . The Gibbs free energy differences were determined to be 0.93 ± 0.18 and 1.68 ± 0.08 kcal/mol for ZZ-EZ and ZZ-EE, respectively. Unlike 1S, temperature-dependent NMR analysis of 1O could not be completed because the compound underwent thermal decomposition at the elevated temperatures.