Crystal structure of (E)-2-[1-(1,3-benzodioxol-5-yl)ethylidene]-N-ethylhydrazine-1-carbothioamide

In the title compound, C12H15N3O2S, the 1,3-benzdioxole fragment is nearly planar [the maximum deviation being 0.0515 (14) Å], the N—N—C(=S)—N fragment is also nearly planar [the maximum deviation being 0.0480 (10) Å], and the dihedral angle between their mean planes is 23.49 (10)°. In the crystal, molecules are linked by pairs of N—H⋯S hydrogen bonds, forming inversion dimers. The dimers are stacked along the a axis with neighbouring columns having the same direction; however, the molecules show different orientations leading to a centrosymmetric arrangement. In the crystal, the methylene group of the ethyl substituent and the terminal methyl H atoms are disordered over two sets of sites and were refined using a split model with an occupancy ratio of 0.5:0.5.

The molecular structure of the title compound, which matches the asymmetric unit, is not planar [the mean deviation from planarity for non-H atoms, and excluding the disordered C11/C11′ entity, amounts to 0.3794 (17) Å for C5]. The maximum deviation from the mean plane of the non-H atoms of the 1,3-benzodioxole fragment amounts to 0.0515 (14) Å for C7 and for the N1/N2/C10/S1/N3 fragment amounts 0.0480 (10) Å for N2, with the dihedral angle between the planes being 23.49 (10)°.
In the crystal, the molecules are connected by pairs of N2-H1N2···S1 intermolecular hydrogen bonds building dimers.
The dimers are stacked along a-axis and although the neighbour columns have the same direction, the dimeric units show different orientations leading to a centrosymmetric structure ( Figure 2 and Table 1).

S1.1. Synthesis and crystallization
Starting materials are commercially available and were used without further purification. The synthesis of the title compound was adapted from a previously procedure (Freund & Schander, 1902). In a hydrochloric acid catalized reaction, a mixture of 3′,4′-(methylenedioxy)acetophenone (10 mmol) and 4-ethyl-3-thiosemicarbazide (10 mmol) in ethanol (80 mL) was refluxed for 4 h. After cooling and filtering, the title compound was obtained. Colourless crystal grown in DMSO by the slow evaporation of the solvent.

S1.2. Refinement
The C-H H atoms were positioned with idealized geometry (methyl H atoms were allowed to rotate but not to tip) and refined isotropic with U iso (H) = 1.2U eq (C) (1.5 for methyl H atoms) using a riding model with C-H = 0.94 Å for aromatic, C-H = 0.98 Å for methylene and C-H = 0.97 Å for methyl H atoms. The N-H H atoms were located in a difference map and were refined isotropic with varying coordinates in the beginning. Finally, the N-H distances were set to ideal values of 0.87 Å and they were refined isotropic with U iso (H) = 1.2U eq (N) using a riding model. The methylene C atom C11 is disordered in two orientations and were refined using a split model with occupancy of 0.5:0.5.

Figure 1
The molecular structure of the title compound with labeling and displacement ellipsoids drawn at the 40% probability level. Disorder is shown with full and open bonds.

Figure 2
Crystal structure of the title compound with hydrogen bonding shown as dashed lines (see Table 1  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.28 e Å −3 Δρ min = −0.23 e Å −3 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (