Crystal structure of S-octyl (E)-3-(4-methoxybenzylidene)dithiocarbazate

As already observed in similar molecules, the dithiocarbazate group in the title compound, C17H26N2OS2, adopts an EE configuration with respect to the C=N bond of the benzylidene moiety. In the crystal, molecules are connected into inversion dimers by pairs of N—H⋯S hydrogen bonds. The dimers are linked by weak π–π interactions, with centroid-to-centroid distances of 3.723 (11) Å, forming chains parallel to [110].


S2. Structural commentary
The molecule of the title compound is shown in Fig. 1. The Schiff base exists in thione tautomeric form with the dithiocarbazate fragment adopting an EE configuration with respect to the C═N bond of the benzylidene moiety. The β-nitrogen and the thioketo sulphur are trans located with respect to the C9-N2 bond. With the exception of the S-octyl chain, the atoms of the 3-(4-methoxybenzylidene)dithiocarbazate group are approximately co-planar (r.m.s. deviation = 0.253 Å) indicating electron delocalization within it. The bond lengths and angles are closely comparable to those detected in Shexyl (E)-3-(4-methylbenzylidene)dithiocarbazate (Howlader et al., 2015) and in the S-hexyl analogue (Begum et al., 2015), characterized by a shorter alkyl chain.

S3. Supramolecular features
The crystal packing of the title compound evidences molecules connected into centrosymmetric dimers (Fig. 2) by pairs of N-H···S hydrogen bonds (Table 1), which are further linked by weak π-π stacking interactions (centroid-to-centroid distances of 3.723 (11) Å) to form chains parallel to the [1 1 0] direction.

S5. Synthesis and crystallization
To an ethanolic solution of KOH (2.81 g, 0.05 mol) hydrazine hydrate (2.50 g, 0.05 mol, 99%) was added and the mixture was stirred at 273 K. To this solution carbon disulfide (3.81 g, 0.05 mol) was added dropwise with constant stirring for one hour. Then 1-bromooctane (9.65 g, 0.05 mol) was added dropwise with vigorous stirring at 273 K for an additional hour. Finally, 4-methoxybenzaldehyde (6.81 g, 0.05 mol) in ethanol was added and the mixture refluxed for 30 min. The mixture was filtered while hot and then the filtrate was cooled to 273 K giving a precipitate of the Schiff base product, which was recrystallized from ethanol at room temperature and dried in a vacuum desiccator over anhydrous CaCl 2 .
Colourless crystals, suitable for X-ray diffraction of the compound were obtained by slow evaporation of an

S6. Refinement
Hydrogen atoms were located geometrically and treated as riding atoms with C-H = 0.98-0.99 Å and U ĩso (H) = 1.2U eq (C). The hydrogen atom at N2 was located on the difference Fourier map and freely refined.

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 50% probability level.   Special details Geometry. ENTER SPECIAL DETAILS OF THE MOLECULAR GEOMETRY Refinement. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F 2 . R-factor (gt) are based on F. The threshold expression of F 2 > 2.0 σ(F 2 ) is used only for calculating R-factor (gt).