Figure 1

The optimized structures of keto-enol tautomers, transition state (TS) and rotamer (Rot) of 4-(methylsulfanyl)-3[(1Z)-1-(2 phenylhydrazinylidene) ethyl] quinoline-2(1H)-one in gas phase and ethanol (in parentheses) at B3LYP/6-31G(d,p) level of theory.