Crystal structure of N-[(methylsulfanyl)carbonyl]urea

In the crystal of (MeS)C(O)NHC(O)NH2, the molecules are connected via N—H⋯O hydrogen bonds, forming ribbon-like chains.


Chemical context
We have recently reported that dimethyl cyanocarbonimidodithioate (MeS) 2 C N-C N is an N-donor ligand, coordinating to metal centres (Diop et al., 2016). In an attempt to broaden data on the coordination ability of this ligand, we have initiated here a study of the interactions between dimethyl cyanocarbonimidodithioate and CrO 2 Cl 2 which yielded the title compound whose X-ray study is reported in this work. Surprisingly, the dimethyl cyanocarbonimidodithioate has undergone redox reactivity at both the cyanide (N1/C1) and the imido (N2/C2) functionalities. The carbon atoms associated with these groups have been oxidized to an amide and both nitrogen atoms now sport hydrogen atoms. One methylthiol group has been removed during this reaction. Presumably adventitious water is the source of the oxygen and hydrogen. This was unexpected reactivity. It is not known if or how the CrO 2 Cl 2 plays a role in this reaction.

Structural commentary
The starting dimethyl cyanocarbonimidodithioate (MeS) 2 C N-C N has undergone oxidation yielding the title compound (MeS)C(O)NHC(O)NH 2 (Fig. 1) Bruno et al., 2004) because of the different substituents on the carbon atoms. The C2-S1-C3 bond angle is 99.22 (7) . The torsion angles are close to zero or 180 , which is consistent with a nearly planar molecule (r.m.s. deviation for the non-hydrogen atoms = 0.055 Å ). An intramolecular N1-H1NBÁ Á ÁO2 hydrogen bond generates an S(6) ring (see Table 1).

Supramolecular features
In the crystal, the compound forms a hydrogen-bonded dimer with a molecule related through the inversion center at ( 1 2 , 1 2 , 0) [N1Á Á ÁO1 ii ; symmetry code: (ii) Àx + 1, Ày + 1, Àz). This 'head-to-head' arrangement forces the non-interacting thiomethyl groups to be on the exterior of the chain. These hydrogen-bonded dimers propagate into a one-dimensional chain parallel to the b axis ( Fig. 2) through hydrogen bonds from N1Á Á ÁO1 i and N2Á Á ÁO2 iii [symmetry codes: (i) x, y À 1, z; (iii) x, y + 1, z]. The ribbons are oriented approximately parallel to the [301] plane. The compactness and the stability of the structure are consolidated through van der Waals forces and weak C-HÁ Á ÁO and C-HÁ Á ÁS hydrogen bonds (Table 1).

Synthesis and crystallization
All chemicals are purchased from Aldrich Company (Germany) and used as received. Dimethyl cyanocarbonimidodithioate was mixed in acetonitrile with CrO 2 Cl 2 in a 1:1 ratio: a green solution was obtained. Two colourless crystalsone of which being this studied compound -suitable for a single-crystal X-ray diffraction study were obtained after a slow solvent evaporation at room temperature (303 K).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. Urea hydrogen atoms were located from a difference Fourier map and refined freely. Methyl hydrogen atoms were included in geometrically calculated positions and allowed to rotate to minimize their contribution to electron density with C-H = 0.98 Å and U iso (H) = 1.5U eq (C3).

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.