Structure and solid–liquid phase transition thermodynamics of N-(diethylaminothiocarbonyl)benzimido derivatives

A set of three N-(diethylaminothiocarbonyl)benzimido derivatives was structurally characterized by solid state single crystal X-ray diffractometry. The temperature, standard molar enthalpies, and entropies of fusion were measured and derived using differential scanning calorimetry, including two more derivatives, whose structures have been published before. The compounds were further analysed by solid state FTIR spectroscopy and the experimental FTIR spectra were compared with the calculated gas phase spectra at the B3LYP/6-311+G(d) level of theory. The structural results for the set were further used in the interpretation of thermophysical phase transition properties of the title compounds. A detailed molecular picture of N-(diethylaminothiocarbonyl)benzimido derivatives was obtained from Natural Bond Order (NBO) analysis. The combination of the applied methods reveals a deeper insight into the structures of this type of compound.