Download citation
Download citation
link to html
An N,N′-disubstituted di­thio­ox­amide derivative reacts with 1,2-di­bromo­ethane to produce the title compound, C18H18N2S2, a heterocycle with a double Schiff base. In the crystal structure, the mol­ecule of the title compound lies on a twofold axis. Weak C—H...π interactions are the principal intermolecular forces, mediating the formation of layers parallel to the ab plane. Each mol­ecule participates as donor and acceptor in two such contacts.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103021000/fa1032sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103021000/fa1032Isup2.hkl
Contains datablock I

pdf

Portable Document Format (PDF) file https://doi.org/10.1107/S0108270103021000/fa1032sup3.pdf
Supplementary material

CCDC reference: 226120

Comment top

The chemistry of sulfur compounds has been the subject of intensive research in organic chemistry. As versatile intermediates and precursors, sulfur compounds have been employed to achieve the syntheses of many target compounds that are otherwise difficult to access, and thus sulfur has played an increasingly important role in organic synthesis. Organic sulfur compounds have also found important applications as? organic conductors and superconductors, and in the life sciences (Page, 1999).

Thioamides are important organic sulfur compounds. The electronegativity of the S atom and the special electronic structure of these compounds make them more reactive than the corresponding amides, and thioamides take part in diverse chemical reactions. These compounds are of both academic and industrial interest because of their high stability and lack of odour, and because they can be synthesized and refined easily (Sosnicki et al., 2001). More recently, some thioamides have shown wide? bioactivities and have been used as anti-inflammatory and fungistatic reagents (Matysiak et al., 2000) and as antituberculins. Thioamides have also served as special reagents used as chain terminators in Sanger-DNA sequencing (Schwarzer et al., 2001) and as versatile intermediates in the syntheses of antitumor agents.

We have investigated the reaction of N,N'-di(2-methylphenyl)dithiooxamide with 1,2-dibromoethane in the presence of potassium carbonate and have found that the product, (I), is a 1,4-dithiacyclohexane with a double Schiff base (see scheme). Such compounds are versatile intermediates in the synthesis of organic compounds because of their exceptional structures, and they have special utility in the synthesis of bioactive compounds (Jorgensen, 2000).

The crystal data show that the bond lengths and angles in (I) have unexceptional values and that there is a twofold axis in the molecule. The S—Csp3, S—Csp2 and Csp2Nsp bond lengths are 1.793 (3), 1.754 (2) and 1.258 (3) Å, respectively, and are similar to those found for the compound reported by Ozarowski et al. (1988), in which the S—Csp3, S—Csp2 and Csp2Nsp bond lengths are 1.796 (3), 1.751 (2) and 1.263 (4) Å, respectively.

Recently, there has been increased interest in non-covalent hydrogen-bridged interactions involving π acceptors (Ni et al., 2003). Jeffrey (1997) mentions this possibility and classifies these interactions as weak hydrogen bonds. In (I), weak C—H···π interactions play an important role; indeed, every molecule makes such contacts to two neighbors [C9—H9b···Cg1i; symmetry code: (i) 0.5 − x,-0.5 + y,z; Cg1i is the center of gravity of the aromatic ring]. The molecule is packed into a layer structure, with aromatic rings acting as weak proton acceptors (see Fig. 2 and Table 2). The layers lie parallel to the ab plane and are stacked along the c axis, with molecules in ?adjacent layers having alternate orientations (adjacent layers are related by a c-glide perpendicular to the b axis; Fig. 3).

Experimental top

A solution of N,N'-di(2-methylphenyl)dithiooxamide (1.2 g, 4.0 mmol) and potassium carbonate (1.1 g, 8.0 mmol) in anhydrous DMSO (8 ml) was stirred at ~303–313 K for 1 h. 1,2-Dibromoethane (4.3 g, 22.9 mmol) was added slowly, and the reaction mixture was kept at 333–338 K for 4 h, until all the N,N'-di(2-methylphenyl)dithiooxamide had disappeared (monitored by thin-layer chromatography). The mixture was cooled, ice water was added and the organic compound was extracted with petroleum ether. The solvent was removed in vacuo and the title compound was separated on a column of alumina with petroleum ether and ethyl acetate as eluants for stepwise elution. Yellow single crystals of (I) suitable for X-ray crystallographic analysis were obtained by recrystallization from a mixture of petroleum ether and ethyl acetate. **Cg1 is the center of gravity of the phenyl ring C1 - C6.

Refinement top

The structure was solved by direct methods. All H atoms were positioned geometrically and refined as riding atoms, with isotropic thermal parameters set to 1.2Ueq or 1.5Ueq of the parent atoms. The distances to H atoms were set by the program and are in the range 0.93–0.97 Å.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), drawn with displacement ellipsoids at the 30% probability level.
[Figure 2] Fig. 2. The crystal packing in (I), viewed along the c axis and showing the C—H···π short contact.
[Figure 3] Fig. 3. The crystal packing in (I). The layers are parallel to the ab plane and stacked along c, with molecules in a given layer oriented oppositely to those in adjacent layers.
2,3-Bi(2-methylphenylimino)-1,4-dithiacyclohexane top
Crystal data top
C18H18N2S2F(000) = 688
Mr = 326.46Dx = 1.287 Mg m3
Orthorhombic, PbcnMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2abCell parameters from 2043 reflections
a = 6.7333 (9) Åθ = 3.2–24.4°
b = 12.6195 (16) ŵ = 0.31 mm1
c = 19.827 (3) ÅT = 293 K
V = 1684.7 (4) Å3Prism, yellow
Z = 40.3 × 0.25 × 0.2 mm
Data collection top
CCD area-detector
diffractometer
1941 independent reflections
Radiation source: sealed tube1270 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.044
ϕ and ω scansθmax = 27.5°, θmin = 2.1°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 88
Tmin = 0.91, Tmax = 0.93k = 1016
9287 measured reflectionsl = 2225
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.058Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.147H-atom parameters constrained
S = 1.00 w = 1/[σ2(Fo2) + (0.05P)2 + 1.3P]
where P = (Fo2 + 2Fc2)/3
1941 reflections(Δ/σ)max < 0.001
101 parametersΔρmax = 0.68 e Å3
0 restraintsΔρmin = 0.81 e Å3
Crystal data top
C18H18N2S2V = 1684.7 (4) Å3
Mr = 326.46Z = 4
Orthorhombic, PbcnMo Kα radiation
a = 6.7333 (9) ŵ = 0.31 mm1
b = 12.6195 (16) ÅT = 293 K
c = 19.827 (3) Å0.3 × 0.25 × 0.2 mm
Data collection top
CCD area-detector
diffractometer
1941 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
1270 reflections with I > 2σ(I)
Tmin = 0.91, Tmax = 0.93Rint = 0.044
9287 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0580 restraints
wR(F2) = 0.147H-atom parameters constrained
S = 1.00Δρmax = 0.68 e Å3
1941 reflectionsΔρmin = 0.81 e Å3
101 parameters
Special details top

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 F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 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 (Å2) top
xyzUiso*/Ueq
S10.02580 (13)0.11165 (6)0.16204 (4)0.0686 (3)
N10.1607 (4)0.29881 (16)0.20454 (11)0.0586 (6)
C10.2742 (4)0.30486 (19)0.14447 (12)0.0514 (7)
C20.4483 (5)0.2476 (2)0.13862 (15)0.0643 (8)
H20.48470.20070.17260.077*
C30.5676 (5)0.2594 (2)0.08328 (16)0.0705 (8)
H30.68340.21980.07930.085*
C40.5157 (5)0.3298 (3)0.03380 (15)0.0689 (8)
H40.59630.33820.00390.083*
C50.3457 (5)0.3877 (2)0.03998 (14)0.0621 (8)
H50.31260.43580.00620.075*
C60.2204 (4)0.37701 (19)0.09524 (13)0.0529 (7)
C70.0352 (4)0.4414 (2)0.10194 (14)0.0598 (7)
H7A0.07790.39800.09150.090*
H7B0.04040.50020.07130.090*
H7C0.02390.46710.14730.090*
C80.0562 (4)0.21875 (19)0.21749 (12)0.0495 (6)
C90.0579 (5)0.0094 (2)0.21801 (14)0.0677 (8)
H9A0.19740.02000.22810.081*
H9B0.04400.05890.19610.081*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0913 (6)0.0540 (4)0.0606 (5)0.0039 (4)0.0056 (4)0.0159 (3)
N10.0832 (17)0.0427 (12)0.0499 (12)0.0035 (11)0.0156 (12)0.0027 (9)
C10.0680 (18)0.0400 (13)0.0462 (13)0.0082 (12)0.0075 (13)0.0061 (11)
C20.083 (2)0.0516 (16)0.0584 (17)0.0045 (15)0.0060 (16)0.0005 (13)
C30.070 (2)0.0679 (19)0.073 (2)0.0032 (16)0.0141 (17)0.0096 (16)
C40.073 (2)0.081 (2)0.0530 (16)0.0179 (18)0.0134 (15)0.0064 (16)
C50.074 (2)0.0633 (18)0.0488 (15)0.0184 (16)0.0047 (14)0.0075 (13)
C60.0568 (16)0.0464 (14)0.0555 (15)0.0129 (12)0.0028 (13)0.0022 (12)
C70.0652 (18)0.0520 (15)0.0622 (16)0.0111 (14)0.0037 (14)0.0004 (13)
C80.0649 (17)0.0371 (12)0.0464 (13)0.0040 (12)0.0032 (12)0.0009 (10)
C90.081 (2)0.0521 (16)0.0705 (18)0.0064 (15)0.0107 (16)0.0172 (14)
Geometric parameters (Å, º) top
S1—C81.754 (2)C4—H40.9300
S1—C91.793 (3)C5—C61.390 (4)
N1—C81.258 (3)C5—H50.9300
N1—C11.417 (3)C6—C71.494 (4)
C1—C21.382 (4)C7—H7A0.9600
C1—C61.383 (4)C7—H7B0.9600
C2—C31.368 (4)C7—H7C0.9600
C2—H20.9300C8—C8i1.495 (5)
C3—C41.369 (4)C9—C9i1.489 (6)
C3—H30.9300C9—H9A0.9700
C4—C51.364 (4)C9—H9B0.9700
C8—S1—C9101.73 (12)C1—C6—C7120.9 (2)
C8—N1—C1121.1 (2)C5—C6—C7121.6 (3)
C2—C1—C6120.5 (3)C6—C7—H7A109.5
C2—C1—N1120.0 (2)C6—C7—H7B109.5
C6—C1—N1119.2 (3)H7A—C7—H7B109.5
C3—C2—C1120.6 (3)C6—C7—H7C109.5
C3—C2—H2119.7H7A—C7—H7C109.5
C1—C2—H2119.7H7B—C7—H7C109.5
C2—C3—C4119.7 (3)N1—C8—C8i117.34 (18)
C2—C3—H3120.1N1—C8—S1123.79 (19)
C4—C3—H3120.1C8i—C8—S1118.78 (15)
C5—C4—C3119.8 (3)C9i—C9—S1111.3 (2)
C5—C4—H4120.1C9i—C9—H9A109.4
C3—C4—H4120.1S1—C9—H9A109.4
C4—C5—C6121.9 (3)C9i—C9—H9B109.4
C4—C5—H5119.0S1—C9—H9B109.4
C6—C5—H5119.0H9A—C9—H9B108.0
C1—C6—C5117.5 (3)
Symmetry code: (i) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C9—H9B···Cg1ii0.972.813.683 (3)150
Symmetry code: (ii) x+1/2, y1/2, z.

Experimental details

Crystal data
Chemical formulaC18H18N2S2
Mr326.46
Crystal system, space groupOrthorhombic, Pbcn
Temperature (K)293
a, b, c (Å)6.7333 (9), 12.6195 (16), 19.827 (3)
V3)1684.7 (4)
Z4
Radiation typeMo Kα
µ (mm1)0.31
Crystal size (mm)0.3 × 0.25 × 0.2
Data collection
DiffractometerCCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.91, 0.93
No. of measured, independent and
observed [I > 2σ(I)] reflections
9287, 1941, 1270
Rint0.044
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.058, 0.147, 1.00
No. of reflections1941
No. of parameters101
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.68, 0.81

Computer programs: SMART (Bruker, 2000), SMART, SAINT (Bruker, 2000), SHELXTL (Bruker, 2000), SHELXTL.

Selected geometric parameters (Å, º) top
S1—C81.754 (2)N1—C11.417 (3)
S1—C91.793 (3)C8—C8i1.495 (5)
N1—C81.258 (3)C9—C9i1.489 (6)
C8—S1—C9101.73 (12)N1—C8—S1123.79 (19)
C8—N1—C1121.1 (2)C8i—C8—S1118.78 (15)
N1—C8—C8i117.34 (18)
Symmetry code: (i) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C9—H9B···Cg1ii0.972.8133.683 (3)150
Symmetry code: (ii) x+1/2, y1/2, z.
 

Follow Acta Cryst. C
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds