Received 17 May 2004
S-Ethyl N-benzoyldithiocarbamate: two independent hydrogen-bonded R(8) dimers of different symmetry linked into chains by a C-H(arene) interaction
John N. Low,a Justo Cobo,b Henry Insuasty,c Martin Estrada,c Edward Cortésc and Christopher Glidewelld*
aDepartment of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen AB24 3UE, Scotland,bDepartamento de Química Inorgánica y Orgánica, Universidad de Jaén, 23071 Jaén, Spain,cDepartamento de Química, Universidad de Nariño, Cuidad Universitaria, Torobajo, AA1175 Pasto, Colombia, and dSchool of Chemistry, University of St Andrews, Fife KY16 9ST, Scotland
The title compound, C10H11NOS2, crystallizes with Z' = 2 in space group C2/c. The molecules are linked by two N-HS hydrogen bonds [HS = 2.60 and 2.62 Å, NS = 3.350 (2) and 3.490 (2) Å, and N-HS = 143 and 172°] into two distinct types of (8) dimer, viz. one generated by inversion and the other by a twofold rotation axis. A single C-H(arene) hydrogen bond links the two types of dimer into chains.
It has been shown (Elmore et al., 1956; Nash et al., 1969) that alkanethiols, RSH, react smoothly with aroylisothiocyanates, ArCONCS, to give S-alkyl N-aroyldithiocarbamates, (ArCO)NHC(=S)SR, in good yields. We report here the molecular and supramolecular structures of the title compound, (PhCO)NHC(=S)SEt, (I), which is an important intermediate in the preparation of S,S-dialkyl N-aroyliminodithiocarbonates used in the synthesis of many organic compounds (Augustín et al., 1980). We have modified the reported method for the synthesis of S-methyl N-benzoyldithiocarbamate (Elmore et al., 1956), so enhancing the yield from 49 to 87%.
The title compound crystallizes in space group C2/c, with Z' = 2 (Fig. 1). The bond lengths (Table 1), which are normal for their types (Allen et al., 1987), are, in general, almost identical in the two independent molecules, as are the overall molecular conformations. However, the two torsion angles defining the orientation of the benzene rings relative to the rest of the nearly planar molecular skeletons differ by 22°. This fact alone suffices to preclude the possibility of any additional symmetry.
Such a possibility is also ruled out by the observation that each type of molecule forms a hydrogen-bonded dimer but that these have different symmetries. For molecules of type 1 (Fig. 1a), atom N12 in the molecule at (x, y, z) acts as a hydrogen-bond donor to thione atom S13 in the molecule at (1 - x, 1 - y, 1 - z), so generating a centrosymmetric (8) dimer (Bernstein et al., 1995) centred at (, , ) (Fig. 2a). However, for molecules of type 2 (Fig. 1b), atom N22 at (x, y, z) acts as a donor to thione atom S23 at (1 - x, y, - z), so that this (8) dimer (Fig. 2b) lies across the twofold rotation axis along (, y, ). The dimensions of the two independent N-HS hydrogen bonds (Table 2) are markedly different.
Although the NS distance is above the sum of the conventional van der Waals radii (3.3 Å; Bondi, 1964), an analysis (Allen et al., 1997) of hydrogen bonds having a secondary amine donor and a thione-type S atom as the acceptor, using data retrieved from the Cambridge Structural Database (Allen, 2002), indicated mean HS, NS and N-HS parameters of 2.46 (1) Å, 3.40 (1) Å and 158 (1)°, respectively, in such bonds involving the neutral species R1R2C=S as an acceptor, and 2.51 (1) Å, 3.44 (1) Å and 158 (1)°, respectively, in such bonds involving neutral thioureas as an acceptor. Accordingly, the N-HS interactions in (I) appear to be fairly typical of such hydrogen bonds.
Each unit cell contains four dimers of each type, and the two types are linked into chains by a single C-H(arene) hydrogen bond. Atoms C46 in the type 2 molecules at (x, y, z) and (1 - x, y, - z) lie in the dimer across the twofold axis along (, y, ). These atoms act as hydrogen-bond donors, respectively, to the C31-C36 rings in the type 1 molecules at (- + x, + y, z) and ( - x, + y, - z), which are themselves components of the type 1 dimers centred at (0, 1, ) and (1, 1, 1), respectively. Within these type 1 dimers, the molecules at ( - x, - y, 1 - z) and ( + x, - y, + z) similarly accept hydrogen bonds from atoms C46 in the type 2 molecules at (1 - x, 2 - y, 1 - z) and (1 + x, 2 - y, + z), respectively, which themselves lie in the type 2 dimers across the rotation axes along (, -y, ) and (, -y, ). Propagation of this single C-H(arene) hydrogen bond by inversion and rotation thus links dimers of the two types into a chain of rings running parallel to the  direction (Fig. 3). Four chains pass through each unit cell, but there are no direction-specific interactions between adjacent chains.
| || Figure 1 |
The two independent molecules in (I), showing the atom-labelling scheme in (a) the type 1 molecule and (b) the type 2 molecule. Displacement ellipsoids are drawn at the 30% probability level.
| || Figure 2 |
The two independent hydrogen-bonded dimers in the structure of (I), showing (a) that generated by inversion, where atoms marked with an asterisk (*) are at the symmetry position (1 - x, 1 - y, 1 - z), and (b) that generated by rotation, where atoms marked with an asterisk (*) are at the symmetry position (1 - x, y, - z).
| || Figure 3 |
A stereoview of part of the crystal structure of (I), showing the formation of the  chain of rings linking the two types of (8) dimer.
Benzoyl chloride (5 ml, 0.043 mol) was added to a solution of potassium thiocyanate (4.1 g, 0.043 mol) in acetonitrile (75 ml) and this mixture was heated under reflux for 15 min to afford benzoyl isothiocyanate. The mixture was cooled to 273 K under an inert atmosphere; ethanethiol (35 ml, 0.47 mol) was added, and this mixture was then stirred at room temperature for 27 h. Ice-water was added and the title compound was extracted with ethyl acetate (3 × 25 ml). The combined organic extracts were dried over anhydrous sodium sulfate and the solvent was removed under reduced pressure. The resulting yellow solid was recrystallized from ethanol to give crystals of (I) suitable for single-crystal X-ray diffraction [yield 87%, m.p. 348 K; literature (Nash et al., 1969) m.p. 352-353 K, yield 49%].
The systematic absences permitted C2/c and Cc as possible space groups; C2/c was selected and confirmed by the structure analysis. All H atoms were located from difference maps and subsequently treated as riding atoms, with C-H distances of 0.95 (aromatic), 0.98 (CH3) or 0.99 Å (CH2), an N-H distance of 0.88 Å, and Uiso(H) values of 1.2Ueq(C,N) or 1.5Ueq(Cmethyl).
Data collection: KappaCCD Server Software (Nonius, 1997); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).
Supplementary data for this paper are available from the IUCr electronic archives (Reference: SK1733 ). Services for accessing these data are described at the back of the journal.
X-ray data were collected at the EPSRC X-ray Crystallographic Service, University of Southampton, England; the authors thank the staff for all their help and advice. JNL thanks NCR Self-Service, Dundee, for grants that have provided computing facilities for this work. JC thanks the Consejería de Educación y Ciencia (Junta de Andalucía, Spain) and the Universidad de Jaén for financial support. HI, ME and EC thank COLCIENCIAS and UDENAR (Universidad de Nariño) for financial support.
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