DFT study, and natural bond orbital (NBO) population analysis of 2-(2-Hydroxyphenyl)-1-azaazulene tautomers and their mercapto analouges

Geometry optimization

Figure 2 lists the tautomeric structures of 2HPhAZ and 2MPhAZ (enolimines/thiol and ketoenamines/thione forms). Table 1 lists all the optimized structural properties determined in gas phase, and ethanol at the B3LYP/6–311 +  + G(2d,2p) level of theory. Table 1 shows that the bond lengths in the tautomeric structure of 2HPhAZ (enolimines and ketoenamines form) are shorter than those in the thiol and thione forms of the mercapto homologue, but the estimated bond angles have shown the opposite in both gas and ethanol phases. The mercapto analogue’s bond angles…