Separation or combination of non-covalently linked partners provides polymorphs of N-(aryl)-2-(propan-2-ylidene)hydrazine carbothioamides

Abstract

Two polymorphs of N-(2-methoxyphenyl)-2-(propan-2ylidene)hydrazine carbothioamide have R²₂(8)-type hydrogen-bonded homo-dimers formed by N–H⋯S interactions. The difference between the two polymorphs originated due to weak C_(sp³)–H⋯S interactions in their respective self-assemblies. Also, three polymorphs of N-(4-nitrophenyl)-2-(propan-2ylidene)hydrazine carbothioamide were characterised by diffraction and spectroscopic techniques. One of the polymorphs out of the three polymorphs of N-(4-nitrophenyl)-2-(propan-2ylidene)hydrazine carbothioamide has two symmetry non-equivalent molecules in a unit cell. These symmetry non-equivalent molecules exhibited two independent self-assemblies in the lattice. One set of symmetry-independent molecules formed a zig-zag chain assisted by C–H⋯S interactions and possessed R²₁(11) hydrogen-bonded units; the other set of symmetry-independent molecules consisted of R²₂(8)-type N–H⋯S-bonded cyclic homo-dimers. The other two polymorphs comprised independent assemblies of these components. One polymorph was composed of R²₂(8) homo-dimers without C_(sp³)–H⋯S interactions, whereas the third polymorph consisted of R²₁(11) hydrogen-bonded units with bifurcated C–H⋯S bonds. The bifurcated hydrogen bond of the third polymorph possessed a sulphur atom as the pivot with an angle ∼133.9°, which was a relatively large bite angle for a bifurcated hydrogen bond. The characteristic spectroscopic and thermal features of all the polymorphs were presented. In this class of compounds, the hydrogen bond hierarchy may be avoided by a complementary effect of lower hierarchical interactions.