Fig. 6. (a) Comparison of NBO energies of n → π* interactions in 1ocb and 2ocb. (b) Correlation of log K₂ with the difference in n → π* NBO energies of 1aocb and 2aocb. Optimized structures and populations of isomers of 1focb and 2focb (c), as well as 1gocb and 2gocb (d).