The article deals with conformational behaviour of 2-methoxy-2'-hydroxythiobenzanilides. The CS-NH group of these compounds preferentially adopts the Z-conformation.
Entropy favours the Z-conformer over the E-conformer, whereas enthalpy slightly favours the E-conformer over the Z-conformer. The rotational barrier about the CS-NH bond was determined to be (81.5 +/- 0.4) kJ/mol.
No significant rotational barrier was found on the Ar-CS and Ar-NH bonds. All experimental outcomes are compared with the results of quantum-chemical calculations.