Substituent effects on the trans/cis isomerization and stability of diazenes

The substituent effects on the trans/cis isomerization and the stability for the diazenes HN(1)N(2)R (R = H, F, OH, OCF3, OCH3, CN, CHO, NH2, OH, CH3) have been studied at the B3LYP, MP4 and G3 level of theories. The results indicate that the charge variation on nitrogen atoms can be characterized by Hammett substituent constant and the electronegativity of substituent. The variation of the isomerization barriers can be attribute to the substitution induced fluctuations of the atomic charge in the NN bond. The isodesmic reaction study suggests that the π-donating ability of substituents dominates the stability of the diazene derivatives.