Crystal structure of the biclotymol–<Emphasis Type="Italic">N,N</Emphasis>-dimethylacetamide solvate 1:1: experimental and theoretical conformational analysis of biclotymol molecule

The crystal structure of the N,N-dimethylacetamide–biclotymol 1:1 solvate has been determined at room temperature by X-ray single-crystal diffraction. The molecular geometry of the biclotymol molecule is compared to the geometries observed in the N,N-dimethylformamide and dimethylsulfoxide solvates, and in the unsolvated form Phase-I. Rotational energy profile of the isolated molecule was obtained by semi-empirical AM1 calculations with respect to two selected torsional angles, which were rotated from 0° to 360° by steps of 10°. Not only, we find the two conformations experimentally observed, but also the conformation proposed by simple force fields calculations 30 years ago. Moreover, we propose three additional possible conformations that may offer potential candidates for the structure biclotymol Phase-II, which remains to be solved.