Crystal structure of (2E)-N-methyl-2-[(4-oxo-4H-chromen-3-yl)methylidene]hydrazinecarbothioamide

In the title compound, C12H11N3O2S, the dihedral angle between the 4H-chromen-4-one ring system and the –CH=N—NH—CS—NH– unit is 6.22 (1)°. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R 2 2(14) loops. The dimers are reinforced by a pair of C—H⋯O interactions, which generate R 2 2(10) loops.


S1. Comment
Thiosemicarbazones are of considerable interest because of their versatile chemistry and various biological activites such as antitumor, antibacterial, antiviral, antiamoebic and antimalarial (Kelly et al., 1996). Schiff bases derived from 3formylchromones have attracted much attention due to their biological functions such as enzyme inhibition (Khan et al., 2009;Tu et al., 2013).
In the crystal, inversion dimers linked by pairs of N-H···O hydrogen bonds generate R 2 2 (14) loops. The dimers are reinforced by a pair of C-H···O interactions, which generate R 2 2 (10) loops.

S2. Experimental
1.05 g (0.01 mol) of N-methylhydrazinecarbothioamide was dissolved in 20 ml of hot ethanol and to this 1.74 g of 4oxo-4H-Chromene-3-carbaldehydein 10 ml of ethanol was added and continuously stirred for a period of 10 min with continuous stirring. The reaction mixture was refluxed for 2 h and allowed to cool whereby shining white was filtered and washed thoroughly with ethanol and then dried in vaccum. The compound was recrystallized from hot ethanol to yield colourless blocks in 92% yield.

S3. Refinement
All H atoms were fixed geometrically and allowed to ride on their parent C atoms, with C-H distances fixed in the range 0.93-0.97 Å with U iso (H) = 1.5U eq (C) for methyl H atoms and 1.2U eq (C) for all other H atoms.  The molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level.

Figure 2
The packing of the title compound with hydrogen bonds represented by dashed lines. Hydrogen atoms not involved in these bonds are omitted for clarity.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.22 e Å −3 Δρ min = −0.24 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 C1