Crystal structure of (E)-2-[1-(benzo[d][1,3]dioxol-5-yl)ethylidene]-N-methylhydrazine-1-carbothioamide

In the title compound, C11H13N3O2S, there is a short intramolecular N—H⋯N contact. The benzo[d][1,3]dioxole ring system is approximately planar (r.m.s. deviation = 0.025 Å) and makes a dihedral angle of 56.83 (6)° with the mean plane of the methylthiosemicarbazone fragment [–N—N—C(=S)—N—C; maximum deviation = 0.1111 (14) Å for the imino N atom]. In the crystal, molecules are linked via pairs of N—H⋯S hydrogen bonds, forming inversion dimers. The dimers are connected by N—H⋯S hydrogen bonds into layers parallel to (100). The H atoms of both methyl groups are disordered over two sets of sites and were refined with occupancy ratios of 0.5:0.5 and 0.75:0.25.


S1. Structural commentary
In our research we are interested in the synthesis of thiosemicarbazone derivatives of natural products. Herein, we report the synthesis and crystal structure of 1-(2H-1,3-benzodioxol-5-yl)ethanone 4-methylthiosemicarbazone, a product of the reaction between 3′,4′-(methylenedioxy)acetophenone and 4-methylthiosemicarbazide. The ketone is a natural product obtained from the South American rosewood trees that belong to the Lauraceae family (Mors et al., 1957).
In the title molecule, Fig. 1, the torsion angle for the N1-N2-C10-N3 entity is 10.2 (2)°. The maximum deviation from the mean plane of the non-H atoms for the C1-C9/O1-O2 fragment and for the C10-C11/N1-N3/S1 fragment amount to 0.2844 (14) Å and 0.1111 (12) Å, respectively, and the angle between their mean planes is 55.39 (4) °. The molecule has two disordered methyl groups. The H atoms of the terminal methyl substituent, C11, are disordered over two sets of sites with an occupancy ratio of 0.75:0.25, those of the other methyl substituent, C9, attached to the Schiff base are disordered over two sets of sites with an occupancy ratio of 0.5:0.5 (Fig. 1).
In the crystal, the molecules are linked via pairs of N2-H1N2···S1 hydrogen bonds into inversion dimers. These dimers are connected by weak N3-H1N3···S1 hydrogen bonds into layers, that are parallel to the bc plane. Finally, an intramolecular N3-H1N3···N1 hydrogen bond is also observed (Figs. 2 and 3, and Table 1).

S2. Synthesis and crystallization
The synthesis of the title compound was adapted from a previously reported procedure (Freund & Schander, 1902). In a hydrochloric acid catalyzed reaction, a mixture of 3′,4′-(methylenedioxy)acetophenone (10 mmol) and 4-Methyl-3-thiosemicarbazide (10 mmol) in ethanol (80 ml) was refluxed for 6 h. After cooling and filtering, the title compound was obtained. Colourless crystals were obtained in DMSO by the slow evaporation of the solvent.

S3. Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The NH H atoms were located in a difference Fourier map and were refined as riding atoms with N-H = 0.88 Å and with U iso (H) = 1.5U eq (N). The Cbound H atoms were positioned with idealized geometry and refined as riding atoms: C-H = 0.95 -0.99 Å with U iso (H) = 1.5U eq (C) for methyl H atoms and = 1. The molecular structure of the title compound with atom labelling. Displacement ellipsoids are drawn at the 40% probability level. Disordered H atoms are shown with white and light gray interior colours and the short intramolecular N-H···N contact is shown as a dashed line (see Table 1 for details).

Figure 2
A view of the intramolecular and intermolecular hydrogen bonds (dashed lines) in the crystal structure of the title compound (see Table 1 for details of the hydrogen bonding and the symmetry codes; disordered H atoms are not shown for clarity).

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.