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Mol­ecules of the title compound, C20H28O4S2, the first compound with a tetra­oxacyclo­hexa­cosane ring to be structurally characterized, lie on crystallographic centres of inversion, but have approximate C2h mol­ecular symmetry. The parallel thio­phene rings are almost exactly planar; the overall conformation of the mol­ecule is chair-like. The mol­ecules have voids that could, in principle, accommodate small guest mol­ecules, although in the crystal structure access to these voids is blocked by neighbouring mol­ecules.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270106004999/fa1181sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270106004999/fa1181Isup2.hkl
Contains datablock I

CCDC reference: 605673

Comment top

Since their discovery in 1977 (Shirakawa et al., 1977), conjugated polymers have played an important role in modern science. Among the conjugated polymers studied to date, alkoxy- and dialkoxypolythiophenes (Skompska et al., 2005), and especially ethylenedioxythiophene (EDOT), have proved to be the most interesting among these materials (Groenendal et al., 2003; Ronali et al., 2005). Owing to several distinct advantages, polyethylenedioxythiophene (PEDOT) has rapidly acquired a prominent position among conducting polymers. A unique combination of moderate band gap and low oxidation potential confers on PEDOT an exceptional stability of the oxidized charged state, which furthermore exhibits high conductivity and good optical transparency in the visible spectroscopic region (Jonas & Schrader, 1991). To date, a large family of poly(alkylenedioxythiophenes), and therefore alkylenedioxythiophenes themselves, have been synthesized in order to elucidate the structure–property relationships in these materials (Kumar et al., 1998).

There are only 38 fragments of 3,4-oxo-substituted thiophenes in the Cambridge Structural Database (CSD, Version?; Allen, 2002); of these, 30 contain the 3,4-ethylenedioxythienyl group. Only two structures have the longer oxo-chains: 3,4-bis(hexadecyloxy)thiophene (CSD refcode ABUQET) and a dithiaporphyrin derivative, 2,3,12,13-tetrabutoxy-5,10,15,20-tetraphenyl-21,23-dithiaporphyrin (Agarwal et al., 2002). The crystal structure of the title compound, (I), is the first example of a molecule with two thiophene moieties connected by long chains. Surprisingly, it is also the first crystal structure of a molecule that possesses a tetraoxacyclohexacosane ring.

The molecule of (I) is symmetrical (Fig. 1a) and lies on a centre of inversion in space group Pbca. Moreover, there are two other approximate symmetry elements, namely a twofold axis through the midpoints of the C9—C10 and C9i—C10i bonds [symmetry code (i) −x, 2 − y, 1 − z], and a mirror plane perpendicular to this axis and containing the S atoms and the midpoints of the C3—C4 and C3i—C4i bonds. Thus, the overall symmetry of the molecule is closest to C2h.

The molecular dimensions are typical (Table 1). The five-membered thiophene ring is planar to within experimental error [maximum deviation from the least squares plane is 0.003 (1) Å For which atom?]. Also, the deviations of the O atoms from this plane are almost negligible [O—C—C—O torsion angle 0.2 (3)°]. The conformation of the eight-membered chain can be analyzed in terms of its torsion angles (Table 1) and can be described as a-sc-a-a-a-sc-a. This conformation results in a chair-like overall conformation of the molecule (Fig. 1b).

The molecule has a void that, in principle, could accommodate small guest molecules [diagonal O···O distances across the void are 6.702 (3) and 6.754 (3) Å; Fig. 2]. However, in reality, neighbouring molecules completely block access to this void.

Only very weak intermolecular C—H···S interactions can be found in the crystal structure of (I) (H···S distances of ca 3.1 Å and C—H···S angles close to 160°). Therefore, van der Waals forces seem to be responsible for the crystal packing.

Experimental top

The synthesis of the title compound was reported by Czardybon et al. (2003). Crystals for X-ray data collection were grown from a methanol solution.

Computing details top

Data collection: KM-4 User's Guide (Kuma Diffraction, 1991); cell refinement: KM-4 User's Guide; data reduction: KM-4 User's Guide; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Stereochemical Workstation Operation Manual (Siemens, 1989); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. (a) A perspective view of the molecule of (I). Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. (b) A side view of the molecule of (I), showing the chair-like conformation.
[Figure 2] Fig. 2. van der Waals sphere representation of (I).
1,8,14,20-Tetraoxa-11,23-dithiatricyclo[21.3.0.09,13]hexacosa- 9,12,21,24-tetraene top
Crystal data top
C20H28O4S2F(000) = 848
Mr = 396.54Dx = 1.260 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 73 reflections
a = 9.595 (2) Åθ = 3.3–20.1°
b = 8.267 (2) ŵ = 0.28 mm1
c = 26.350 (5) ÅT = 295 K
V = 2090.1 (8) Å3Block, colourless
Z = 40.6 × 0.4 × 0.3 mm
Data collection top
Kuma KM-4
diffractometer
Rint = 0.000
Radiation source: fine-focus sealed tubeθmax = 25.1°, θmin = 2.6°
Graphite monochromatorh = 011
ω/2θ scansk = 09
1845 measured reflectionsl = 310
1845 independent reflections2 standard reflections every 100 reflections
1125 reflections with I > 2σ(I) intensity decay: 0.7%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.036All H-atom parameters refined
wR(F2) = 0.105 w = 1/[σ2(Fo2) + (0.0684P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.98(Δ/σ)max = 0.001
1845 reflectionsΔρmax = 0.27 e Å3
175 parametersΔρmin = 0.21 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0208 (19)
Crystal data top
C20H28O4S2V = 2090.1 (8) Å3
Mr = 396.54Z = 4
Orthorhombic, PbcaMo Kα radiation
a = 9.595 (2) ŵ = 0.28 mm1
b = 8.267 (2) ÅT = 295 K
c = 26.350 (5) Å0.6 × 0.4 × 0.3 mm
Data collection top
Kuma KM-4
diffractometer
Rint = 0.000
1845 measured reflections2 standard reflections every 100 reflections
1845 independent reflections intensity decay: 0.7%
1125 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0360 restraints
wR(F2) = 0.105All H-atom parameters refined
S = 0.98Δρmax = 0.27 e Å3
1845 reflectionsΔρmin = 0.21 e Å3
175 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
S10.08426 (7)1.22216 (8)0.73732 (2)0.0656 (3)
C20.1251 (3)1.0485 (3)0.70430 (8)0.0547 (6)
H20.191 (2)0.975 (3)0.7171 (9)0.062 (7)*
C30.0558 (2)1.0419 (2)0.65948 (7)0.0459 (5)
C40.0317 (2)1.1799 (2)0.65102 (8)0.0484 (5)
C50.0266 (3)1.2860 (3)0.69010 (9)0.0582 (6)
H50.071 (3)1.389 (3)0.6924 (8)0.067 (7)*
O60.06023 (15)0.92543 (17)0.62306 (5)0.0524 (4)
C70.1369 (3)0.7818 (3)0.63569 (9)0.0504 (5)
H7A0.233 (3)0.810 (3)0.6403 (8)0.058 (7)*
H7B0.094 (2)0.732 (3)0.6640 (9)0.056 (6)*
C80.1262 (2)0.6703 (3)0.59068 (8)0.0488 (5)
H8A0.153 (2)0.562 (3)0.6014 (7)0.046 (5)*
H8B0.032 (3)0.663 (3)0.5826 (7)0.048 (6)*
C90.2117 (3)0.7236 (3)0.54524 (8)0.0536 (5)
H9A0.209 (2)0.845 (3)0.5437 (8)0.065 (7)*
H9B0.306 (3)0.692 (3)0.5493 (9)0.069 (7)*
C100.1579 (2)0.6637 (3)0.49468 (8)0.0496 (5)
H10A0.132 (2)0.549 (3)0.4961 (8)0.057 (6)*
H10B0.072 (3)0.710 (3)0.4859 (9)0.065 (7)*
C110.2591 (2)0.6880 (3)0.45107 (8)0.0497 (5)
H11A0.336 (2)0.603 (3)0.4533 (8)0.055 (6)*
H11B0.297 (2)0.796 (3)0.4528 (8)0.048 (5)*
C120.1953 (3)0.6754 (3)0.39905 (9)0.0533 (6)
H12A0.142 (2)0.580 (3)0.3947 (9)0.067 (7)*
H12B0.265 (3)0.678 (3)0.3741 (9)0.065 (7)*
O130.10513 (16)0.81246 (17)0.39278 (5)0.0553 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0852 (5)0.0734 (4)0.0383 (3)0.0022 (3)0.0061 (3)0.0061 (3)
C20.0622 (13)0.0608 (14)0.0412 (12)0.0027 (12)0.0068 (11)0.0060 (10)
C30.0511 (11)0.0463 (11)0.0403 (10)0.0011 (9)0.0104 (10)0.0011 (9)
C40.0543 (11)0.0473 (12)0.0435 (11)0.0003 (9)0.0093 (10)0.0010 (9)
C50.0692 (14)0.0557 (14)0.0498 (12)0.0086 (12)0.0091 (11)0.0034 (11)
O60.0623 (9)0.0481 (8)0.0470 (8)0.0122 (7)0.0035 (7)0.0044 (6)
C70.0546 (13)0.0488 (12)0.0478 (12)0.0079 (11)0.0042 (11)0.0067 (10)
C80.0482 (13)0.0422 (12)0.0560 (13)0.0018 (9)0.0017 (10)0.0040 (10)
C90.0548 (12)0.0539 (12)0.0521 (13)0.0046 (11)0.0026 (11)0.0062 (10)
C100.0461 (12)0.0475 (12)0.0551 (13)0.0030 (10)0.0002 (10)0.0009 (10)
C110.0453 (11)0.0481 (13)0.0558 (13)0.0054 (10)0.0038 (10)0.0054 (10)
C120.0563 (13)0.0477 (13)0.0559 (13)0.0092 (11)0.0048 (12)0.0075 (10)
O130.0673 (9)0.0493 (9)0.0494 (8)0.0145 (7)0.0059 (7)0.0072 (7)
Geometric parameters (Å, º) top
S1—C51.720 (3)C8—H8A0.97 (2)
S1—C21.724 (3)C8—H8B0.93 (2)
C2—C31.356 (3)C9—C101.512 (3)
C2—H20.94 (2)C9—H9A1.00 (2)
C3—O61.360 (2)C9—H9B0.94 (3)
C3—C41.434 (3)C10—C111.518 (3)
C4—O13i1.353 (3)C10—H10A0.98 (2)
C4—C51.354 (3)C10—H10B0.94 (3)
C5—H50.95 (2)C11—C121.505 (3)
O6—C71.435 (3)C11—H11A1.02 (2)
C7—C81.506 (3)C11—H11B0.97 (2)
C7—H7A0.96 (3)C12—O131.435 (3)
C7—H7B0.95 (2)C12—H12A0.95 (3)
C8—C91.517 (3)C12—H12B0.93 (3)
C5—S1—C291.79 (11)C10—C9—C8114.54 (19)
C3—C2—S1111.22 (18)C10—C9—H9A106.4 (13)
C3—C2—H2128.0 (15)C8—C9—H9A107.8 (13)
S1—C2—H2120.8 (15)C10—C9—H9B109.4 (15)
C2—C3—O6128.9 (2)C8—C9—H9B110.2 (15)
C2—C3—C4112.96 (19)H9A—C9—H9B108 (2)
O6—C3—C4118.13 (18)C9—C10—C11113.88 (19)
O13i—C4—C5129.6 (2)C9—C10—H10A111.7 (12)
O13i—C4—C3118.34 (17)C11—C10—H10A108.5 (12)
C5—C4—C3112.1 (2)C9—C10—H10B112.5 (15)
C4—C5—S1111.92 (18)C11—C10—H10B108.7 (14)
C4—C5—H5127.5 (14)H10A—C10—H10B101 (2)
S1—C5—H5120.5 (14)C12—C11—C10114.8 (2)
C3—O6—C7115.95 (16)C12—C11—H11A107.2 (12)
O6—C7—C8106.81 (18)C10—C11—H11A109.1 (12)
O6—C7—H7A108.8 (13)C12—C11—H11B105.1 (12)
C8—C7—H7A108.2 (13)C10—C11—H11B109.1 (12)
O6—C7—H7B108.5 (13)H11A—C11—H11B111.4 (16)
C8—C7—H7B109.0 (13)O13—C12—C11107.20 (17)
H7A—C7—H7B115.2 (19)O13—C12—H12A108.4 (15)
C7—C8—C9114.01 (19)C11—C12—H12A112.8 (14)
C7—C8—H8A108.4 (11)O13—C12—H12B109.1 (14)
C9—C8—H8A110.6 (11)C11—C12—H12B110.5 (14)
C7—C8—H8B106.6 (13)H12A—C12—H12B109 (2)
C9—C8—H8B111.2 (13)C4i—O13—C12116.68 (16)
H8A—C8—H8B105.6 (18)
C5—S1—C2—C30.17 (18)C2—C3—O6—C77.2 (3)
S1—C2—C3—O6179.90 (17)C4—C3—O6—C7173.32 (18)
S1—C2—C3—C40.4 (2)C3—O6—C7—C8179.25 (18)
C2—C3—C4—O13i179.35 (18)O6—C7—C8—C972.4 (3)
O6—C3—C4—O13i0.2 (3)C7—C8—C9—C10154.3 (2)
C2—C3—C4—C50.6 (3)C8—C9—C10—C11168.1 (2)
O6—C3—C4—C5179.91 (19)C9—C10—C11—C12163.08 (19)
O13i—C4—C5—S1179.47 (17)C10—C11—C12—O1368.5 (3)
C3—C4—C5—S10.4 (2)C11—C12—O13—C4i176.95 (18)
C2—S1—C5—C40.15 (19)
Symmetry code: (i) x, y+2, z+1.

Experimental details

Crystal data
Chemical formulaC20H28O4S2
Mr396.54
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)295
a, b, c (Å)9.595 (2), 8.267 (2), 26.350 (5)
V3)2090.1 (8)
Z4
Radiation typeMo Kα
µ (mm1)0.28
Crystal size (mm)0.6 × 0.4 × 0.3
Data collection
DiffractometerKuma KM-4
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
1845, 1845, 1125
Rint0.000
(sin θ/λ)max1)0.596
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.036, 0.105, 0.98
No. of reflections1845
No. of parameters175
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.27, 0.21

Computer programs: KM-4 User's Guide (Kuma Diffraction, 1991), KM-4 User's Guide, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), Stereochemical Workstation Operation Manual (Siemens, 1989), SHELXL97.

Selected geometric parameters (Å, º) top
S1—C51.720 (3)C4—O13i1.353 (3)
S1—C21.724 (3)O6—C71.435 (3)
C3—O61.360 (2)C12—O131.435 (3)
C5—S1—C291.79 (11)O13i—C4—C3118.34 (17)
C3—C2—S1111.22 (18)C5—C4—C3112.1 (2)
C2—C3—O6128.9 (2)C4—C5—S1111.92 (18)
C2—C3—C4112.96 (19)C3—O6—C7115.95 (16)
O6—C3—C4118.13 (18)C4i—O13—C12116.68 (16)
O13i—C4—C5129.6 (2)
C3—O6—C7—C8179.25 (18)C9—C10—C11—C12163.08 (19)
O6—C7—C8—C972.4 (3)C10—C11—C12—O1368.5 (3)
C7—C8—C9—C10154.3 (2)C11—C12—O13—C4i176.95 (18)
C8—C9—C10—C11168.1 (2)
Symmetry code: (i) x, y+2, z+1.
 

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