Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100001402/bk1513sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270100001402/bk1513Isup2.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270100001402/bk1513IVsup3.hkl |
CCDC references: 145537; 145538
A mixture of 1,4-benzoquinone (54 g, 0.5 mol), dimethyl disulfide (28.2 g, 0.3 mol) and montmorillonite K-10 (ex-Fluka) impregnated with 2 mmol g-1 ZnCl2 (50 g; Clark et al., 1996) in dichloromethane (500 ml) was stirred for 16 h at 293 K. Filtration of the reaction mixture afforded a red solid comprised of the clay catalyst and the product, (I). The filtrate contained a small amount of (I), excess dimethyl disulfide and the quinol, (II), formed during re-oxidation of the reaction intermediate. Soxhlet extraction of the red solid with dichloromethane over 20 h gave (I) as a red solid (34 g, 63%). Recrystallization from ethanol afforded red plates. Compound (IV) was prepared using K-10 montmorillonite clay and the method described previously by Clark et al. (1996), and was oxidized to its sulfonyl derivative using a method employed by Aitken et al. (1994). Crystals of (IV) were obtained by slow crystallization from aqueous ethanol.
For both compounds, H atoms were treated as riding, with default C—H distances and Uiso values. The absolute structure of compound (IV) could not be established in this analysis because no Friedel pairs were collected.
Data collection: CAD-4 Software (Enraf-Nonius, 1989) for (I); MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988) for (IV). Cell refinement: CAD-4 Software for (I); MSC/AFC Diffractometer Control Software for (IV). For both compounds, data reduction: TEXSAN (Molecular Structure Corporation, 1994); program(s) used to solve structure: SAPI91 (Fan, 1991); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: TEXSAN; software used to prepare material for publication: SHELXL97.
C8H8O2S2 | Z = 1 |
Mr = 200.26 | F(000) = 104 |
Triclinic, P1 | Dx = 1.525 Mg m−3 |
a = 4.032 (2) Å | Cu Kα radiation, λ = 1.54178 Å |
b = 5.717 (1) Å | Cell parameters from 25 reflections |
c = 9.626 (1) Å | θ = 10–20° |
α = 86.04 (1)° | µ = 5.17 mm−1 |
β = 80.60 (2)° | T = 293 K |
γ = 86.09 (3)° | Plate, red |
V = 218.0 (1) Å3 | 0.36 × 0.28 × 0.08 mm |
Enraf-Nonius CAD-4 diffractometer | 757 reflections with I<2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.030 |
Graphite monochromator | θmax = 68.0°, θmin = 5.0° |
ω–2θ scans | h = −4→4 |
Absorption correction: empirical (using intensity measurements) ψ-scan (3 reflections) (North et al., 1968) | k = −6→6 |
Tmin = 0.22, Tmax = 0.66 | l = −11→11 |
1535 measured reflections | 3 standard reflections every 200 reflections |
791 independent reflections | intensity decay: <0.5% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.043 | H-atom parameters constrained |
wR(F2) = 0.111 | w = 1/[σ2(Fo2) + (0.0671P)2 + 0.0706P] where P = (Fo2 + 2Fc2)/3 |
S = 1.15 | (Δ/σ)max < 0.001 |
791 reflections | Δρmax = 0.39 e Å−3 |
56 parameters | Δρmin = −0.32 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.060 (10) |
C8H8O2S2 | γ = 86.09 (3)° |
Mr = 200.26 | V = 218.0 (1) Å3 |
Triclinic, P1 | Z = 1 |
a = 4.032 (2) Å | Cu Kα radiation |
b = 5.717 (1) Å | µ = 5.17 mm−1 |
c = 9.626 (1) Å | T = 293 K |
α = 86.04 (1)° | 0.36 × 0.28 × 0.08 mm |
β = 80.60 (2)° |
Enraf-Nonius CAD-4 diffractometer | 757 reflections with I<2σ(I) |
Absorption correction: empirical (using intensity measurements) ψ-scan (3 reflections) (North et al., 1968) | Rint = 0.030 |
Tmin = 0.22, Tmax = 0.66 | 3 standard reflections every 200 reflections |
1535 measured reflections | intensity decay: <0.5% |
791 independent reflections |
R[F2 > 2σ(F2)] = 0.043 | 0 restraints |
wR(F2) = 0.111 | H-atom parameters constrained |
S = 1.15 | Δρmax = 0.39 e Å−3 |
791 reflections | Δρmin = −0.32 e Å−3 |
56 parameters |
x | y | z | Uiso*/Ueq | ||
S1 | 0.08707 (14) | −0.02197 (9) | 0.16908 (5) | 0.0402 (3) | |
O1 | 0.2593 (5) | −0.3313 (3) | 0.66402 (18) | 0.0496 (5) | |
C1 | 0.0574 (5) | −0.0295 (4) | 0.3500 (2) | 0.0313 (5) | |
C2 | 0.1864 (5) | −0.1979 (4) | 0.4351 (2) | 0.0349 (5) | |
H2 | 0.3073 | −0.3280 | 0.3955 | 0.042* | |
C3 | 0.1404 (5) | −0.1802 (4) | 0.5863 (2) | 0.0338 (5) | |
C4 | 0.2975 (7) | −0.2992 (4) | 0.1260 (3) | 0.0455 (6) | |
H4A | 0.5134 | −0.3105 | 0.1565 | 0.068* | |
H4B | 0.3274 | −0.3126 | 0.0258 | 0.068* | |
H4C | 0.1646 | −0.4234 | 0.1726 | 0.068* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.0562 (5) | 0.0385 (4) | 0.0247 (4) | 0.0085 (3) | −0.0079 (3) | −0.0006 (2) |
O1 | 0.0707 (12) | 0.0401 (9) | 0.0353 (9) | 0.0213 (8) | −0.0131 (8) | 0.0040 (7) |
C1 | 0.0348 (10) | 0.0304 (10) | 0.0280 (10) | 0.0005 (8) | −0.0054 (8) | 0.0006 (8) |
C2 | 0.0435 (11) | 0.0300 (10) | 0.0300 (11) | 0.0070 (8) | −0.0064 (9) | −0.0017 (8) |
C3 | 0.0405 (11) | 0.0290 (11) | 0.0314 (11) | 0.0034 (8) | −0.0083 (8) | 0.0017 (8) |
C4 | 0.0562 (14) | 0.0445 (13) | 0.0338 (12) | 0.0080 (10) | −0.0033 (10) | −0.0081 (10) |
S1—C1 | 1.724 (2) | C1—C3i | 1.504 (3) |
S1—C4 | 1.788 (2) | C2—C3 | 1.447 (3) |
O1—C3 | 1.227 (3) | C3—C1i | 1.504 (3) |
C1—C2 | 1.353 (3) | ||
C1—S1—C4 | 102.83 (11) | C1—C2—C3 | 121.5 (2) |
C2—C1—C3i | 119.5 (2) | O1—C3—C2 | 121.8 (2) |
C2—C1—S1 | 127.68 (17) | O1—C3—C1i | 119.1 (2) |
C3i—C1—S1 | 112.84 (15) | C2—C3—C1i | 119.1 (2) |
C4—S1—C1—C2 | 4.5 (2) | S1—C1—C2—C3 | −179.95 (16) |
C4—S1—C1—C3i | −175.06 (15) | C1—C2—C3—O1 | −179.4 (2) |
C3i—C1—C2—C3 | −0.4 (3) | C1—C2—C3—C1i | 0.4 (3) |
Symmetry code: (i) −x, −y, −z+1. |
C10H10O2S2 | F(000) = 236 |
Mr = 226.30 | Dx = 1.454 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71069 Å |
a = 5.8228 (5) Å | Cell parameters from 25 reflections |
b = 10.440 (1) Å | θ = 10–20° |
c = 8.6217 (9) Å | µ = 0.48 mm−1 |
β = 99.57 (1)° | T = 293 K |
V = 516.8 (1) Å3 | Prismatic, colorless |
Z = 2 | 0.55 × 0.38 × 0.35 mm |
Rigaku-AFC-6S diffractometer | 1063 reflections with I<2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.027 |
Graphite monochromator | θmax = 27.6°, θmin = 2.4° |
ω/2θ scans | h = 0→7 |
Absorption correction: empirical (using intensity measurements) via ψ-scan (3 reflections) (North et al., 1968) | k = 0→13 |
Tmin = 0.78, Tmax = 0.85 | l = −11→11 |
1385 measured reflections | 3 standard reflections every 200 reflections |
1268 independent reflections | intensity decay: 1.3% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.029 | H-atom parameters constrained |
wR(F2) = 0.109 | w = 1/[σ2(Fo2) + (0.0656P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.19 | (Δ/σ)max < 0.001 |
1268 reflections | Δρmax = 0.23 e Å−3 |
128 parameters | Δρmin = −0.29 e Å−3 |
1 restraint | Absolute structure: Flack (1983) |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.07 (15) |
C10H10O2S2 | V = 516.8 (1) Å3 |
Mr = 226.30 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 5.8228 (5) Å | µ = 0.48 mm−1 |
b = 10.440 (1) Å | T = 293 K |
c = 8.6217 (9) Å | 0.55 × 0.38 × 0.35 mm |
β = 99.57 (1)° |
Rigaku-AFC-6S diffractometer | 1063 reflections with I<2σ(I) |
Absorption correction: empirical (using intensity measurements) via ψ-scan (3 reflections) (North et al., 1968) | Rint = 0.027 |
Tmin = 0.78, Tmax = 0.85 | 3 standard reflections every 200 reflections |
1385 measured reflections | intensity decay: 1.3% |
1268 independent reflections |
R[F2 > 2σ(F2)] = 0.029 | H-atom parameters constrained |
wR(F2) = 0.109 | Δρmax = 0.23 e Å−3 |
S = 1.19 | Δρmin = −0.29 e Å−3 |
1268 reflections | Absolute structure: Flack (1983) |
128 parameters | Absolute structure parameter: −0.07 (15) |
1 restraint |
x | y | z | Uiso*/Ueq | ||
S1 | 0.51440 (19) | 0.30871 (11) | 0.07085 (11) | 0.0463 (3) | |
S2 | 0.65668 (15) | 0.47553 (10) | 0.52923 (10) | 0.0388 (2) | |
O1 | 0.6269 (6) | 0.6112 (4) | 0.5389 (4) | 0.0656 (10) | |
O2 | 0.8850 (5) | 0.4247 (4) | 0.5847 (4) | 0.0607 (10) | |
C1 | 0.6643 (6) | 0.3336 (4) | 0.2593 (4) | 0.0366 (8) | |
C2 | 0.5609 (6) | 0.4265 (4) | 0.3340 (4) | 0.0333 (7) | |
C3 | 0.3523 (6) | 0.4818 (4) | 0.2406 (4) | 0.0360 (7) | |
C4 | 0.1984 (7) | 0.5750 (4) | 0.2783 (5) | 0.0471 (10) | |
H4 | 0.2240 | 0.6147 | 0.3762 | 0.057* | |
C5 | 0.0054 (8) | 0.6072 (5) | 0.1664 (6) | 0.0563 (12) | |
H5 | −0.0993 | 0.6681 | 0.1911 | 0.068* | |
C6 | −0.0331 (8) | 0.5507 (6) | 0.0205 (6) | 0.0590 (13) | |
H6 | −0.1625 | 0.5745 | −0.0522 | 0.071* | |
C7 | 0.1169 (7) | 0.4595 (5) | −0.0196 (5) | 0.0522 (11) | |
H7 | 0.0909 | 0.4218 | −0.1187 | 0.063* | |
C8 | 0.3080 (7) | 0.4249 (4) | 0.0910 (4) | 0.0399 (8) | |
C9 | 0.8775 (8) | 0.2541 (5) | 0.3081 (6) | 0.0498 (10) | |
H9A | 0.9323 | 0.2657 | 0.4186 | 0.075* | |
H9B | 0.9965 | 0.2802 | 0.2499 | 0.075* | |
H9C | 0.8408 | 0.1655 | 0.2873 | 0.075* | |
C10 | 0.4619 (8) | 0.4013 (6) | 0.6374 (5) | 0.0538 (12) | |
H10A | 0.5015 | 0.4248 | 0.7462 | 0.081* | |
H10B | 0.4722 | 0.3100 | 0.6273 | 0.081* | |
H10C | 0.3058 | 0.4287 | 0.5975 | 0.081* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.0513 (6) | 0.0555 (6) | 0.0322 (4) | −0.0040 (5) | 0.0068 (4) | −0.0078 (5) |
S2 | 0.0326 (4) | 0.0503 (5) | 0.0313 (4) | −0.0048 (4) | −0.0014 (3) | −0.0061 (4) |
O1 | 0.080 (2) | 0.050 (2) | 0.060 (2) | −0.0099 (18) | −0.0084 (18) | −0.0157 (16) |
O2 | 0.0322 (13) | 0.100 (3) | 0.0459 (16) | 0.0022 (17) | −0.0047 (12) | −0.0082 (18) |
C1 | 0.0355 (17) | 0.043 (2) | 0.0325 (16) | −0.0071 (16) | 0.0085 (13) | 0.0020 (15) |
C2 | 0.0309 (16) | 0.0404 (19) | 0.0281 (15) | −0.0068 (15) | 0.0031 (13) | 0.0026 (14) |
C3 | 0.0353 (15) | 0.0391 (18) | 0.0321 (16) | −0.0068 (18) | 0.0013 (12) | 0.0050 (17) |
C4 | 0.046 (2) | 0.042 (2) | 0.050 (2) | 0.0023 (18) | 0.0010 (18) | −0.0007 (18) |
C5 | 0.045 (2) | 0.053 (3) | 0.069 (3) | 0.010 (2) | 0.004 (2) | 0.011 (2) |
C6 | 0.046 (2) | 0.070 (3) | 0.055 (3) | 0.000 (2) | −0.011 (2) | 0.017 (2) |
C7 | 0.051 (2) | 0.066 (3) | 0.0357 (18) | −0.010 (2) | −0.0065 (16) | 0.008 (2) |
C8 | 0.0403 (19) | 0.047 (2) | 0.0313 (17) | −0.0087 (18) | 0.0031 (14) | 0.0039 (16) |
C9 | 0.047 (2) | 0.051 (3) | 0.053 (2) | 0.006 (2) | 0.0123 (19) | 0.002 (2) |
C10 | 0.045 (2) | 0.084 (4) | 0.034 (2) | −0.003 (2) | 0.0115 (17) | −0.001 (2) |
S1—C1 | 1.731 (4) | C2—C3 | 1.460 (5) |
S1—C8 | 1.736 (4) | C3—C4 | 1.397 (6) |
S2—O1 | 1.431 (4) | C3—C8 | 1.405 (5) |
S2—O2 | 1.437 (3) | C4—C5 | 1.395 (6) |
S2—C2 | 1.759 (4) | C5—C6 | 1.374 (8) |
S2—C10 | 1.763 (5) | C6—C7 | 1.375 (7) |
C1—C2 | 1.359 (6) | C7—C8 | 1.387 (5) |
C1—C9 | 1.494 (6) | ||
C1—S1—C8 | 92.9 (2) | C3—C2—S2 | 121.0 (3) |
O1—S2—O2 | 117.4 (2) | C4—C3—C8 | 118.8 (3) |
O1—S2—C2 | 108.7 (2) | C4—C3—C2 | 130.8 (4) |
O2—S2—C2 | 109.8 (2) | C8—C3—C2 | 110.4 (4) |
O1—S2—C10 | 108.0 (3) | C5—C4—C3 | 118.7 (4) |
O2—S2—C10 | 107.6 (2) | C6—C5—C4 | 121.4 (5) |
C2—S2—C10 | 104.4 (2) | C5—C6—C7 | 120.9 (4) |
C2—C1—C9 | 132.5 (4) | C6—C7—C8 | 118.6 (4) |
C2—C1—S1 | 111.0 (3) | C7—C8—C3 | 121.6 (4) |
C9—C1—S1 | 116.5 (3) | C7—C8—S1 | 127.1 (4) |
C1—C2—C3 | 114.5 (3) | C3—C8—S1 | 111.3 (3) |
C1—C2—S2 | 124.5 (3) | ||
C8—S1—C1—C2 | 0.0 (3) | S2—C2—C3—C8 | −178.3 (3) |
C8—S1—C1—C9 | −179.0 (3) | C8—C3—C4—C5 | 0.5 (6) |
C9—C1—C2—C3 | 179.1 (4) | C2—C3—C4—C5 | −177.7 (4) |
S1—C1—C2—C3 | 0.3 (4) | C3—C4—C5—C6 | −1.0 (7) |
C9—C1—C2—S2 | −3.2 (6) | C4—C5—C6—C7 | 0.6 (8) |
S1—C1—C2—S2 | 178.0 (2) | C5—C6—C7—C8 | 0.4 (7) |
O1—S2—C2—C1 | 142.6 (3) | C6—C7—C8—C3 | −0.9 (7) |
O2—S2—C2—C1 | 12.8 (4) | C6—C7—C8—S1 | 177.4 (3) |
C10—S2—C2—C1 | −102.3 (4) | C4—C3—C8—C7 | 0.4 (6) |
O1—S2—C2—C3 | −39.9 (4) | C2—C3—C8—C7 | 179.0 (4) |
O2—S2—C2—C3 | −169.6 (3) | C4—C3—C8—S1 | −178.1 (3) |
C10—S2—C2—C3 | 75.2 (3) | C2—C3—C8—S1 | 0.5 (4) |
C1—C2—C3—C4 | 177.8 (4) | C1—S1—C8—C7 | −178.7 (4) |
S2—C2—C3—C4 | 0.1 (6) | C1—S1—C8—C3 | −0.3 (3) |
C1—C2—C3—C8 | −0.5 (4) |
Experimental details
(I) | (IV) | |
Crystal data | ||
Chemical formula | C8H8O2S2 | C10H10O2S2 |
Mr | 200.26 | 226.30 |
Crystal system, space group | Triclinic, P1 | Monoclinic, P21 |
Temperature (K) | 293 | 293 |
a, b, c (Å) | 4.032 (2), 5.717 (1), 9.626 (1) | 5.8228 (5), 10.440 (1), 8.6217 (9) |
α, β, γ (°) | 86.04 (1), 80.60 (2), 86.09 (3) | 90, 99.57 (1), 90 |
V (Å3) | 218.0 (1) | 516.8 (1) |
Z | 1 | 2 |
Radiation type | Cu Kα | Mo Kα |
µ (mm−1) | 5.17 | 0.48 |
Crystal size (mm) | 0.36 × 0.28 × 0.08 | 0.55 × 0.38 × 0.35 |
Data collection | ||
Diffractometer | Enraf-Nonius CAD-4 diffractometer | Rigaku-AFC-6S diffractometer |
Absorption correction | Empirical (using intensity measurements) ψ-scan (3 reflections) (North et al., 1968) | Empirical (using intensity measurements) via ψ-scan (3 reflections) (North et al., 1968) |
Tmin, Tmax | 0.22, 0.66 | 0.78, 0.85 |
No. of measured, independent and observed [I<2σ(I)] reflections | 1535, 791, 757 | 1385, 1268, 1063 |
Rint | 0.030 | 0.027 |
(sin θ/λ)max (Å−1) | 0.601 | 0.652 |
Refinement | ||
R[F2 > 2σ(F2)], wR(F2), S | 0.043, 0.111, 1.15 | 0.029, 0.109, 1.19 |
No. of reflections | 791 | 1268 |
No. of parameters | 56 | 128 |
No. of restraints | 0 | 1 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.39, −0.32 | 0.23, −0.29 |
Absolute structure | ? | Flack (1983) |
Absolute structure parameter | ? | −0.07 (15) |
Computer programs: CAD-4 Software (Enraf-Nonius, 1989), MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988), CAD-4 Software, MSC/AFC Diffractometer Control Software, TEXSAN (Molecular Structure Corporation, 1994), SAPI91 (Fan, 1991), SHELXL97 (Sheldrick, 1997), TEXSAN, SHELXL97.
S1—C1 | 1.724 (2) | C1—C2 | 1.353 (3) |
S1—C4 | 1.788 (2) | C1—C3i | 1.504 (3) |
O1—C3 | 1.227 (3) | C2—C3 | 1.447 (3) |
C1—S1—C4 | 102.83 (11) | C1—C2—C3 | 121.5 (2) |
C2—C1—C3i | 119.5 (2) | O1—C3—C2 | 121.8 (2) |
C2—C1—S1 | 127.68 (17) | O1—C3—C1i | 119.1 (2) |
C3i—C1—S1 | 112.84 (15) | C2—C3—C1i | 119.1 (2) |
C4—S1—C1—C2 | 4.5 (2) | S1—C1—C2—C3 | −179.95 (16) |
C4—S1—C1—C3i | −175.06 (15) | C1—C2—C3—O1 | −179.4 (2) |
C3i—C1—C2—C3 | −0.4 (3) | C1—C2—C3—C1i | 0.4 (3) |
Symmetry code: (i) −x, −y, −z+1. |
S1—C1 | 1.731 (4) | S2—O2 | 1.437 (3) |
S1—C8 | 1.736 (4) | S2—C2 | 1.759 (4) |
S2—O1 | 1.431 (4) | S2—C10 | 1.763 (5) |
C1—S1—C8 | 92.9 (2) | O1—S2—C10 | 108.0 (3) |
O1—S2—O2 | 117.4 (2) | O2—S2—C10 | 107.6 (2) |
O1—S2—C2 | 108.7 (2) | C2—S2—C10 | 104.4 (2) |
O2—S2—C2 | 109.8 (2) |
Recently, 2,5-bis(methylthio)-1,4-benzoquinone, (I), has been used to prepare sulfur-quinone polyurethane coatings which are applied to protect iron surfaces. Surprisingly, the synthesis of (I) was not reported until 1998 and then was obtained in only 15% yield by reaction of 1,4-benzoquinone with sodium thiomethoxide (Hu & Nikles, 1998). Using a clay-catalyzed one-step thioalkylation procedure developed in our laboratories (Clark et al., 1996), we have been able to make compound (I) in good yield and on a large scale. Conveniently, one half of the quinone reagent re-oxidizes the intermediate product to yield the product, (I) (scheme). 1H NMR analysis of (I), which is obtained from ethanol as brilliant red crystals, does not allow differentiation of (I) from its 2,3-bis(methylthio) isomer. X-ray analysis showed, however, that the clay-catalyzed synthesis reported herein yielded the 2,5-isomer as the sole product. \scheme
A one-step thioalkylation procedure developed in our laboratory allows addition of –SR groups to aromatics and heteroaromatics (Clark et al., 1996). However, it was clear that reaction of 2,3-methylbenzo[b]thiophene, (III), with dimethyl disulfide over a clay catalyst did not yield the expected 5,6-disubstituted product, but an oily compound in which one of either the 2- or 3-methyl groups had been replaced by an –SCH3 substituent (scheme). Since an ipso-substitution of this type is quite rare and because other spectroscopic methods could not differentiate whether substitution had occurred at the 2- or 3- positions, the product was oxidized to its crystalline sulfonyl derivative using a literature procedure (Aitken et al., 1994) and was subjected to X-ray crystallographic analysis. This analysis showed that the 3-thiomethyl derivative, (IV), had been produced, suggesting that a sulfur-assisted ipso-substitution had taken place.
The structure of (I) is composed of centrosymmetric molecules which are essentially planar [maximum deviation 0.026 (2) Å for C3]. The bond distances agree well with the corresponding values reported for bis-, tris- and tetrakis(thiophenyl)benzoquinones (Cambridge Structural Database; Allen & Kennard, 1993). The S—Csp3 and S—Csp2 bond distances of 1.788 (2) and 1.724 (2) Å, respectively, differ significantly. The bonds C3=O1 [1.227 (3) Å] and C1=C2 [1.353 (3) Å] are double bonds. The Csp2—Csp2 bonds, C1—C3i [1.504 (3) Å; symmetry code: (i) -x, -y, 1 - z] and C2—C3 [1.447 (3) Å], are in excellent agreement with the values reported for the thiophenylbenzoquinone structures mentioned above. The S1—C1—C3i angle of 112.85 (15)° is smaller than the value of 120° expected for a Csp2 C-atom, perhaps because of intermolecular methyl-methyl and methyl-carbonyl interactions.
The molecules of (I) pack in layers which lie perpendiular to the (101) plane. Within the layers there are short S···S interactions of 3.430 (1) Å between the molecules related by inversion centers. There are also short Csp2—H···O type contacts (H···O 2.56 Å and Csp2—H···O 164°) forming a dimeric motif with graph set R22(8) (Fig. 2); similar interactions in the crystal structures of quinones have been discussed by Bernstein et al. (1994).
The structure of (IV) is composed of discrete molecules separated by normal van der Waals distances. The benzothiophene moiety is essentially planar [maximum deviation 0.021 (4) Å for C5], with S2 and C9 of the methylsulfonyl and methyl groups lying 0.045 (5) and 0.022 (6) Å, respectively, on the same side of the plane. The intramolecular repulsion between the two substituents is relieved by the widening of the C2—C1—C9 angle to 132.5 (4)°. The important bond distances are endocyclic S—Csp2 (mean) 1.734 (3), exocyclic S—Csp2 1.759 (4), S—Csp3 1.763 (5), S=O (mean) 1.434 (4) and C—Caromatic (mean) 1.389 (10) Å.