2,5-Bis(methylthio)-1,4-benzoquinone and 2-methyl-3-(methylsulfonyl)-benzo[b]thiophene

Article abstract of DOI:10.1107/S0108270100001402

The structure of 2,5-bis(methylthio)-1,4-benzoquinone, C₈H₈-O₂S₂, is composed of an essentially planar centrosymmetric benzoquinone substituted with two methylthio groups. The important bond distances are S - Csp³ 1.788 (2) and S - Csp² 1.724 (2) A, and the two Csp² - Csp² distances are 1.447 (3) and 1.504 (3) A, which differ significantly. There are short S...S interactions of 3.430 (1) A and Csp² - H...O-type contacts forming a dimeric motif with graph set R²₂(8). The structure of 2-methyl-3-(methylsulfonyl)benzo[b]thiophene, C₁₀H₁₀O₂S₂, is composed of an essentially planar benzothiophene moiety substituted with methyl and methylsulfonyl groups. The mean values of the important bond distances are endocyclic S - Csp² 1.734 (3), S = O 1.434 (4) and C - C_aromatic 1.389 (10) A. The exocyclic S - Csp² and S - Csp³ distances are 1.759 (4) and 1.763 (5) A, respectively.

Full text of DOI:10.1107/S0108270100001402

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
disubstituted product, but an oily compound in which one of
either the 2- or 3-methyl groups had been replaced by an
±SCH3 substituent (see scheme). Since an ipso-substitution of
ISSN 0108-2701
2,5-Bis(methylthio)-1,4-benzoquinone
and 2-methyl-3-(methylsulfonyl)-
benzo[b]thiophene
Masood Parvez,* Shaun T. Mesher and Peter D. Clark
Department of Chemistry, The University of Calgary, 2500 University Drive NW,
Calgary, Alberta, Canada T2N 1N4
Correspondence e-mail: parvez@ucalgary.ca
Received 11 October 1999
Accepted 25 January 2000
The structure of 2,5-bis(methylthio)-1,4-benzoquinone, C8H8-
O2S2, is composed of an essentially planar centrosymmetric
benzoquinone substituted with two methylthio groups. The
important bond distances are SÐCsp3 1.788 (2) and SÐCsp2
2
2
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 crystal-
lographic analysis. This analysis showed that the 3-thiomethyl
derivative, (IV), had been produced, suggesting that a sulfur-
assisted ipso-substitution had taken place.
Ê
1.724 (2) A, and the two Csp ÐCsp distances are 1.447 (3)
Ê
and 1.504 (3) A, which differ signi®cantly. There are short
2
Ê
SÁ Á ÁS interactions of 3.430 (1) A and Csp ÐHÁ Á ÁO-type
contacts forming a dimeric motif with graph set R22(8). The
structure of 2-methyl-3-(methylsulfonyl)benzo[b]thiophene,
C10H10O2S2, is composed of an essentially planar benzothio-
phene moiety substituted with methyl and methylsulfonyl
groups. The mean values of the important bond distances are
endocyclic SÐCsp2 1.734 (3), S O 1.434 (4) and CÐCaromatic
The structure of (I) is composed of centrosymmetric mol-
ecules which are essentially planar [maximum deviation
Ê
0.026 (2) A for C3]. The bond distances agree well with the
2
3
Ê
1.389 (10) A. The exocyclic SÐCsp and SÐCsp distances are
Ê
1.759 (4) and 1.763 (5) A, respectively.
corresponding values reported for bis-, tris- and tetrakis-
(thiophenyl)benzoquinones (Cambridge Structural Database;
Allen & Kennard, 1993). The SÐCsp3 and SÐCsp2 bond
Comment
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 labora-
tories (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
Ê
distances of 1.788 (2) and 1.724 (2) A, respectively, differ
Ê
signi®cantly. The bonds C3 O1 [1.227 (3) A] and C1 C2
2
[1.353 (3) A] are double bonds. The Csp ÐCsp bonds, C1Ð
2
Ê
i
C3 [1.504 (3) A; symmetry code: (i) x, y, 1 z] and C2Ð
Ê
Ê
C3 [1.447 (3) A], are in excellent agreement with the values
1
product to yield the product, (I) (see scheme). H 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.
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
disul®de over a clay catalyst did not yield the expected 5,6-
Figure 1
ORTEPII (Johnson, 1976) drawing of (I) with the atomic numbering
scheme. Displacement ellipsoids have been plotted at the 50%
probability level and H atoms assigned arbitrary radii [symmetry code:
(i) x, y, 1 z].
ꢀ
574 # 2000 International Union of Crystallography
Printed in Great Britain ± all rights reserved
Acta Cryst. (2000). C56, 574±576

organic compounds
The structure of (IV) is composed of discrete molecules
separated by normal van der Waals distances. The benzo-
thiophene moiety is essentially planar [maximum deviation
Ê
0.021 (4) A for C5], with S2 and C9 of the methylsulfonyl and
Ê
methyl groups lying 0.045 (5) and 0.022 (6) A, respectively, on
the same side of the plane. The intramolecular repulsion
between the two substituents is relieved by the widening of the
C2ÐC1ÐC9 angle to 132.5 (4)ꢁ. The important bond
distances are endocyclic SÐCsp2 (mean) 1.734 (3), exocyclic
SÐCsp2 1.759 (4), SÐCsp3 1.763 (5), S O (mean) 1.434 (4)
Ê
and CÐCaromatic (mean) 1.389 (10) A.
Experimental
A mixture of 1,4-benzoquinone (54 g, 0.5 mol), dimethyl disul®de
(28.2 g, 0.3 mol) and montmorillonite K-10 (ex Fluka) impregnated
1
with 2 mmol g 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 ®ltrate contained a small amount of (I), excess
dimethyl disul®de 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.
Figure 2
The unit-cell packing of (I) showing Csp2ÐHÁ Á ÁO-type contacts (thin
lines) forming a dimeric motif.
reported for the thiophenylbenzoquinone structures
mentioned above. The S1ÐC1ÐC3i angle of 112.85 (15)ꢁ is
smaller than the value of 120ꢁ expected for a Csp2 atom,
perhaps because of intermolecular methyl±methyl and
methyl±carbonyl interactions.
Compound (I)
Crystal data
C8H8O2S2
Z = 1
Dx = 1.525 Mg m
Cu Kꢀ radiation
3
Mr = 200.26
Triclinic, P1
a = 4.032 (2) A
The molecules of (I) pack in layers which lie perpendiular to
the (101) plane. Within the layers there are short SÁ Á ÁS
Ê
Ê
Cell parameters from 25
re¯ections
b = 5.717 (1) A
Ê
interactions of 3.430 (1) A between the molecules related by
c = 9.626 (1) A
ꢃ = 10±20ꢁ
ꢄ = 5.17 mm
T = 293 (2) K
Ê
inversion centers. There are also short Csp2ÐHÁ Á ÁO type
1
ꢀ = 86.04 (1)ꢁ
ꢁ = 80.60 (2)ꢁ
ꢂ = 86.09 (3)ꢁ
2
ꢁ
Ê
contacts (HÁ Á ÁO 2.56 A and Csp ÐHÁ Á ÁO 164 ) forming a
2
dimeric motif with graph set R2 (8) (Fig. 2); similar interac-
Plate, red
0.36 Â 0.28 Â 0.08 mm
3
Ê
V = 218.0 (1) A
tions in the crystal structures of quinones have been discussed
by Bernstein et al. (1994).
Data collection
Enraf±Nonius CAD-4 diffract-
ometer
!±2ꢃ scans
757 re¯ections with I > 2ꢅ(I)
Rint = 0.030
ꢃmax = 68ꢁ
Absorption correction: empirical
via scan (3 re¯ections; North
et al., 1968)
Tmin = 0.22, Tmax = 0.66
1535 measured re¯ections
791 independent re¯ections
h = 4 ! 4
k = 6 ! 6
l = 11 ! 11
3 standard re¯ections
every 200 re¯ections
intensity decay: <0.5%
Re®nement
Re®nement on F2
R[F2 > 2ꢅ(F2)] = 0.043
wR(F2) = 0.111
S = 1.15
791 re¯ections
w = 1/[ꢅ2(Fo2) + (0.0671P)2
+ 0.0706P]
where P = (Fo2 + 2Fc2)/3
(Á/ꢅ)max < 0.001
3
Ê
Áꢆmax = 0.39 e A
3
Ê
0.32 e A
Figure 3
56 parameters
H-atom parameters constrained
Áꢆmin
=
ORTEPII (Johnson, 1976) drawing of (IV) with the atomic numbering
scheme. Displacement ellipsoids have been plotted at the 50%
probability level and H atoms assigned arbitrary radii.
Extinction correction: SHELXL97
(Sheldrick, 1997)
Extinction coef®cient: 0.060 (10)
ꢀ
Acta Cryst. (2000). C56, 574±576
Masood Parvez et al. C8H8O2S2 and C10H10O2S2 575

organic compounds
Table 1
Selected geometric parameters (A, ) for (I).
Re®nement
ꢁ
Ê
Re®nement on F2
R[F2 > 2ꢅ(F2)] = 0.029
wR(F2) = 0.109
S = 1.19
1268 re¯ections
w = 1/[ꢅ2(Fo2) + (0.0656P)2]
where P = (Fo2 + 2Fc2)/3
(Á/ꢅ)max < 0.001
S1ÐC1
S1ÐC4
O1ÐC3
1.724 (2)
1.788 (2)
1.227 (3)
C1ÐC2
C1ÐC3i
C2ÐC3
1.353 (3)
1.504 (3)
1.447 (3)
3
Ê
Áꢆmax = 0.23 e A
3
Ê
0.29 e A
Áꢆmin
=
128 parameters
H-atom parameters constrained
Absolute structure: Flack (1983)
Flack parameter = 0.07 (15)
C1ÐS1ÐC4
C2ÐC1ÐC3i
C2ÐC1ÐS1
C3iÐC1ÐS1
102.83 (11)
119.5 (2)
127.68 (17)
112.84 (15)
C1ÐC2ÐC3
O1ÐC3ÐC2
O1ÐC3ÐC1i
C2ÐC3ÐC1i
121.5 (2)
121.8 (2)
119.1 (2)
119.1 (2)
For both compounds, H atoms were treated as riding with default
CÐH distances and Uiso values. The absolute structure of compound
(IV) could not be established in this analysis because no Friedel pairs
were collected.
C4ÐS1ÐC1ÐC2
C4ÐS1ÐC1ÐC3i
C3iÐC1ÐC2ÐC3
4.5 (2)
175.06 (15)
0.4 (3)
S1ÐC1ÐC2ÐC3
C1ÐC2ÐC3ÐO1
C1ÐC2ÐC3ÐC1i
179.95 (16)
179.4 (2)
0.4 (3)
Data collection: CAD-4 Software (Enraf±Nonius, 1989), for (I),
MSC/AFC Diffractometer Control Software (Molecular Structure
Corporation, 1988) for (IV); cell re®nement: 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 re®ne structure: SHELXL97 (Sheldrick,
1997); molecular graphics: TEXSAN; software used to prepare
material for publication: SHELXL97.
Symmetry code: (i) x; y; 1 z.
Compound (IV)
Crystal data
3
C10H10O2S2
Mr = 226.30
Dx = 1.454 Mg m
Mo Kꢀ radiation
The authors thank the Natural Sciences and Engineering
Research Council of Canada for providing the diffractometer
through an equipment grant to the University of Calgary, and
Alberta Sulphur Research Ltd, Calgary, Alberta, for ®nancial
support.
Monoclinic, P21
Ê
Cell parameters from 25
re¯ections
a = 5.8228 (5) A
Ê
b = 10.440 (1) A
ꢃ = 10±20ꢁ
1
Ê
c = 8.6217 (9) A
ꢄ = 0.48 mm
T = 293 (2) K
ꢁ = 99.57 (1)ꢁ
V = 516.8 (1) A
Z = 2
3
Ê
Prismatic, colorless
0.55 Â 0.38 Â 0.35 mm
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: BK1513). Services for accessing these data are
described at the back of the journal.
Data collection
Rigaku AFC-6S diffractometer
!/2ꢃ scans
Absorption correction: empirical
via scan (3 re¯ections; North
et al., 1968)
Tmin = 0.78, Tmax = 0.85
1385 measured re¯ections
1268 independent re¯ections
1063 re¯ections with I > 2ꢅ(I)
Rint = 0.027
max = 27.6ꢁ
ꢃ
References
h = 0 ! 7
k = 0 ! 13
Aitken, R. A., Armstrong, D. P. & Mesher, S. T. E. (1994). Tetrahedron Lett.
35, 6143±6145.
l = 11 ! 11
3 standard re¯ections
every 200 re¯ections
intensity decay: 1.31%
Allen, F. H. & Kennard, O. (1993). Chem. Des. Autom. News, 8, 131±137.
Bernstein, J., Etter, M. C. & Leiserowitz, L. (1994). Structure Correlation,
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Table 2
Selected geometric parameters (A, ) for (IV).
ꢁ
Ê
S1ÐC1
S1ÐC8
S2ÐO1
1.731 (4)
1.736 (4)
1.431 (4)
S2ÐO2
S2ÐC2
S2ÐC10
1.437 (3)
1.759 (4)
1.763 (5)
Molecular Structure Corporation. (1994). TEXSAN. MSC, 3200 Research
Forest Drive, The Woodlands, TX 77381, USA.
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359.
È
Sheldrick, G. M. (1997). SHELXL97. University of Gottingen, Germany.
C1ÐS1ÐC8
O1ÐS2ÐO2
O1ÐS2ÐC2
O2ÐS2ÐC2
92.9 (2)
117.4 (2)
108.7 (2)
109.8 (2)
O1ÐS2ÐC10
O2ÐS2ÐC10
C2ÐS2ÐC10
108.0 (3)
107.6 (2)
104.4 (2)
ꢀ
576 Masood Parvez et al. C8H8O2S2 and C10H10O2S2
Acta Cryst. (2000). C56, 574±576