Conversely, for 1O, the most stable structure was found of the EE isomer. The relative energies of the most stable EZ and ZZ conformers were 1.33 and 1.67 kcal/mol, respectively. Notably, within the ZZ isomer of 1O, the syn/syn conformation that was most stable for 1S was found to be less stable than the syn/anti and anti/anti conformations (Figure ). This destabilization can be attributed to the repulsion between the lone pairs of adjacent oxygen atoms. The distribution ratio of ZZ:EZ:EE, calculated based on the Gibbs free energies of the ensemble, was 11:39:49, which also approximately matched the experimental values.