Experimental and theoretical characterization of N-(diethylcarbamothioyl)benzamide triclinic polymorph

The presence of a monoclinic and triclinic polymorph of the title compound has been investigated by means of several different techniques. With the evidence of a lack of our ability to crystallize the monoclinic polymorph, we tried to define which of the two reported structures is more stable or more probable, not only from the experimental point of view but also from the computational one. A Differential Scanning Calorimetry measurement coupled with a Rietveld analysis of the X-ray powder diffraction pattern, allowed the unequivocal determination of the presence of only the triclinic polymorph among the products of the most widely used synthetic approach. Moreover, a robust approach based on a Molecular Dynamics simulation, allowed a detailed description of the two considered structures up to very fine details, i.e. the atomic displacement parameters, thus enabling a very accurate representation of the considered systems. A crystal morphology prediction, compared with optical microscopy images of the harvested crystals was also performed, confirming the absence of the monoclinic polymorph. These combined approaches evidenced the greater stability of the triclinic polymorph over the monoclinic one.