Ethyl (4-{[(diethylcarbamothioyl)sulfanyl]methyl}-2-oxo-2H-chromen-7-yl)carbamate

In the title compound, C18H22N2O4S2, the 2H-chromene ring system is essentially planar (r.m.s. deviation = 0.012 Å). The molecular conformation is stabilized by a C—H⋯O hydrogen bond. In the crystal, N—H⋯S and C—H⋯O hydrogen bonds occur, the former enclosing an R 2 2(22) ring motif, and lead to the formation of a two-dimensional slab-like network lying parallel to (10-1). π–π interactions are observed between inversion-related aromatic rings [shortest centroid–centroid distance = 3.6300 (11) Å].


Comment
Coumarin and its derivatives are an important class of heterocyclic compound and a number of preparations have been known since late 19th century. Various compounds possessing an azomethine linkage at C-7 have been synthesized and evaluated for their anti-oxidant ability and anti-inflammatory activity. They showed 58% and 54% inhibition of inflammation induced by Carrageenan, which was better than the standard indomethacin (Valizadeha et al., 2005). The luminescent property of Europium chelates of acylated 7-amino coumarins has been used to label proteins at cysteine residues on synthetic oligonucleotides containing a free thiol group (Chen et al., 2008).
Organic dithiocarbamates have attracted a great deal of interest due to their interesting chemistry and wide utility (Zhang et al., 2005). Dithiocarbamates have a wide range of uses and applications and are produced in great quantities throughout the world. Since, brassinin (Mehta et al., 1995) a crucial plant defense first isolated from cabbage, had cancer preventive activity, structural modification on this compound led to the synthesis of sulforamate (Gerhauser et al., 1997) and a series of dithiocarbamates, some of which were found to have in-vitro and in-vivo antitumor activity (Cao et al., 2005). A steadily increasing number of structural studies have been published from our research group on dithiocarbamates. Based on the above literature survey we synthesized the title molecule for its chemical and physical studies.

Experimental
All the chemicals used were of analytical reagent grade and were used directly without further purification. The title compound was synthesized according to the reported method7 (Kumar et al., 2012). The compound is recrystallized by ethanol-chloroform mixture. Colourless needles of the title compound were grown from a mixed solution of Ethanol/Chloroform (V/V = 2/1) by slow evaporation at room temperature. Yield= 91%, m.p. 445 K.

Refinement
All H atoms were positioned geometrically, with N-H = 0.86 Å, C-H = 0.93 Å for aromatic H, C-H = 0.97 Å for methylene H and C-H = 0.96 Å for methyl H and were refined using a riding model with U iso (H) = 1.5U eq (C) for methyl H and U iso (H) = 1.2U eq (C,N) for all other H.

Figure 1
The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen atoms are shown as spheres of arbitrary radius.

Figure 2
The crystal packing of the title compound. N-H···S hydrogen bonds are drawn as dashed lines

Ethyl (4-{[(diethylcarbamothioyl)sulfanyl]methyl}-2-oxo-2H-chromen-7-yl)carbamate
Crystal data  , 5.62; N, 7.10 (calculated); C, 54.84; H, 5.58; N, 7.14 (found). Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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 S1 0.95674 (