4,5-Bis(benzylthio)-1,3-dithiole-2-thione compounds: Crystal structures of [(p-XC6H4CH2)(p-XC6H 4CH2)dmit: X = Y = OMe; X = Y = NO2; and X = OMe, Y = NO2]

Article abstract of DOI:10.1023/A:1009595331369

4,5-Bis(benzylthio)-1,3-dithiole-2-thiones, [(p-XC₆H₄CH₂)(p-XC₆H ₄CH₂)dmit: X = Y = OMe (2); X = OMe, Y = NO₂ (3); and X = NO₂] (4)] have been prepared from benzyl chlorides and [NEt₄]₂[Zn(dmit)₂]. Isostructural compounds, 2 and 3, crystallize in the triclinic space group P1 (Z = 2) with a = 5.2920(10), b = 10.537(2), c = 18.961(4) A, α = 102.79(3), β = 96.33(3), γ = 98.67(3)° for 2; a = 5.292(8), b = 10.528(12), c = 19.01(2) A, α = 102.74(9), β = 96.26(11), γ = 98.56(11)° for 3. Compound 4 also crystallizes in the space group P1 (Z = 4), with a = 9.296(8), b = 13.993(18), c = 16.186(4) A, α = 106.68(3), β = 89.63(3), γ = 99.38(6)°. Molecular differences between 2 and 3, on one hand, and 4, on the other, arise in the disposition of the aryl rings relative to the dmit group. Short S...S contacts in 2 of 3.320(2) A [S3...S3ⁱ (symmetry operation: i: -x + 1, -y + 1, -z)] and in 3 of 3.314(5)A [S3...S3ⁱ (symmetry operation: i: -x + 1, -y, -z + 1)] link molecules into pairs. In 4, an S5A...S2B contact of 3.516(5) A links two independent molecules, A and B, into bimolecular units, which are further connected into chains by S2A...S5Bⁱ contacts (symmetry operation: i: x, y, z - 1) at 3.569(5) A. C-H...O hydrogen bonds are also present in 3 and 4.

Full text of DOI:10.1023/A:1009595331369

Journal of Chemical Crystallography, Vol. 29, No. 11, 1999
4,5-Bis(benzylthio)-1,3-dithiole-2-thione compounds: crystal
structures of [(p-XC6H4CH2)(p-XC6H4CH2)dmit:
XuYuOMe; XuYuNO2; and XuOMe, YuNO2]
Zahid H. Chohan,(1) R. Alan Howie,(1) James L. Wardell,(1)* and
Solange M.S.V. Wardell(1)
Received November 10, 1999
4,5-Bis(benzylthio)-1,3-dithiole-2-thiones, [(p-XC6H4CH2)(p-XC6H4CH2)dmit: XuYuOMe
(2); XuOMe, YuNO2 (3); and XuNO2] (4)] have been prepared from benzyl chlorides
and [NEt4]2[Zn(dmit)2]. Isostructural compounds, 2 and 3, crystallize in the triclinic space
˚
group P1 (Z ϭ 2) with a ϭ 5.2920(10), b ϭ 10.537(2), c ϭ 18.961(4) A, Ͱ ϭ 102.79(3), ͱ ϭ
˚
96.33(3), Ͳ ϭ 98.67(3)Њ for 2; a ϭ 5.292(8), b ϭ 10.528(12), c ϭ 19.01(2) A, Ͱ ϭ 102.74(9),
ͱ ϭ 96.26(11), Ͳ ϭ 98.56(11)Њ for 3. Compound 4 also crystallizes in the space group P1
˚
(Z ϭ 4), with a ϭ 9.296(8), b ϭ 13.993(18), c ϭ 16.186(4) A, Ͱ ϭ 106.68(3), ͱ ϭ 89.63(3),
Ͳ ϭ 99.38(6)Њ. Molecular differences between 2 and 3, on one hand, and 4, on the other,
arise in the disposition of the aryl rings relative to the dmit group. Short S---S contacts in
i
˚
˚
2 of 3.320(2) A [S3---S3 (symmetry operation: i: Ϫx ϩ 1, Ϫy ϩ 1, Ϫz)] and in 3 of 3.314(5)A
[S3---S3i (symmetry operation: i: Ϫx ϩ 1, Ϫy, Ϫz ϩ 1)] link molecules into pairs. In 4, an
˚
S5A---S2B contact of 3.516(5) A links two independent molecules, A and B, into bimolecular
units, which are further connected into chains by S2A---S5Bi contacts (symmetry operation:
˚
i: x, y, z Ϫ 1) at 3.569(5) A. CUH---O hydrogen bonds are also present in 3 and 4.
KEY WORDS: 4,5-Bis(benzylthio)-1,3-dithiole-2-thiones; 1,3-dithiole-2-thione-4,5-dithiolates, dmit
compounds.
Introduction
The nature and extent of the the intermolecular con-
tacts, and the arrays generated, vary with the dmit
Derivatives of 4,5-dimercapto-1,3-dithiole-2-thi-
compound.
Intermolecular contacts have been investigated
one (H2-dmit: 1) have been extensively studied as
heterocyclic compounds,1 coordination compounds,2
precursors of tetrathiafulvalene derivatives1,3,4 and
electronic conducting materials.5 Many dmit com-
pounds in the solid state are associated, particularly
via S---S interactions but also, in appropriate com-
pounds, via sulfur contacts with other elements, e.g.,
metals and oxygen, as illustrated by the compounds
listed in the Cambridge Crystallographic Data Base.6
in three 4,5-bis(benzyl)thio-1,3-dithiole-2-thione
compounds, namely 4,5-bis-(p-methoxybenzylthio)-
1,3-dithiole-2-thione, (2), 4-(p-methoxybenzylthio)-
5-(p-nitrobenzylthio)-1,3-dithiole-2-thione, (3), and
4,5-bis-(p-nitrobenzylthio)-1,3-dithiole-2-thione, 4.
The structures have been compared with that of pre-
viously reported 4,5-bis-(p-bromobenzylthio)-1,3-
dithiole-2-thione 5.7
Experimental section
(1) Department of Chemistry, University of Aberdeen, Old Aber-
deen, AB24 3UE, Scotland. 0044-1224-272930. Fax: 0044-1224-
272921. E-mail: j.wardell@abdn.ac.uk
Melting points were measured on a Kofler hot-
stage and are uncorrected. NMR spectra were re-
* To whom correspondence should be addressed.
1165
1074-1542/99/1100-1165$16.00/0  1999 Plenum Publishing Corporation

1166
Chohan, Howie, Wardell, and Wardell
4-(p-Methoxybenzylthio)-5-(p-nitrobenzylthio)-1,3-
dithiole-2-thione, 3
Solutions of p-O2NC6H4CH2Cl (0.22 g, 1.25
mmol) and p-MeOC6H4CH2Cl (0.20 g, 1.25 mmol) in
CH2Cl2 (20 mL) and [NEt4]2[Zn(dmit)2] (0.90 g, 0.63
mmol) in CH2Cl2 (30 mL) were mixed and refluxed
overnight. The solvent was removed to leave an oil,
which was chromatographed (preparative TLC) on
silica using CH2Cl2/petroleum ether (40–60ЊC) (from
80 : 20 to 95 : 5 v : v) as eluents into three compounds:
2–4. Compound 3, the least mobile, was recrystallized
from CH2Cl2 as a deep-red colored solid, m.p. 157ЊC.
Analysis. Found: C, 47.5; H, 3.0; N, 3.1. Calculated
for C18H15NO3S5: C, 47.7; H, 3.3; N, 3.1%. IR (KBr):
v(CuS) 1056, 1035 cmϪ1. Vis (CH2Cl2): 381, 522 nm.
1H NMR (CDCl3, 250MHz): ͳ: 3.80[s, 3H, OMe],
3.94[s, 2H, CH2], 3.95[s, 2H, CH2], 6.85[d, 2H, J 8.6] &
7.15[d, 2H, J 8.6][anisyl-H], 7.37[d, 2H, J 8.6, H-2,
nitrophenyl ring], 8.17[d, 2H, J 8.6, H-3, nitrophenyl
ring]. 13C NMR (CDCl3, 63MHz): ͳ: 40.0 & 40.5[CH2],
55.2[Me], 114.1[C-3, anisyl ring], 123.9[C-3, nitrophe-
nyl ring], 127.3[C-1, anisyl ring], 129.7, 130.1[C-2, ani-
syl and nitrophenyl rings], 133.5[CuC], 140.0[CuC],
143.4[C-1, nitrophenyl ring], 147.4[C-4, nitrophenyl
ring], 159.4, [C-4, anisyl ring], 210.7[CuS].
corded on a Bruker 250 MHz instrument, IR spectra
on a Philips Analytical PU9800 FTIR instrumen and
visible spectra on a Perkin Elmer Lambda 15 instru-
ment. The compound, [NEt4]2[Zn(dmit)2], was ob-
tained by a published procedure.8
4,5-Bis-(p-methoxybenzylthio)-1,3-dithiole-2-thione, 2
Solutions of p-MeOC6H4CH2Cl (0.39 g, 2.50
mmol) in CH2Cl2 (20 mL) and [NEt4]2[Zn(dmit)2]
(0.45 g, 0.63 mmol) in CH2Cl2 (20 mL) were mixed
and refluxed overnight. The solvent was removed to
leave an oil, which was chromatographed on silica,
using CH2Cl2 as eluent. The title compound was re-
crystallized from CH2Cl2/hexane as a red-brown col-
ored crystalline solid, m.p. 119-122ЊC [lit. value9 m.p.
95ЊC]; yield 0.36 g, 66%. Analysis. Found: C, 51.8;
H, 4.3. Calculated for C19H18O2S5: C, 52.0; H, 4.1%.
IR(KBr): v(CuS) 1058 cmϪ1. Vis (CH2Cl2):378, 521
nm. 1H NMR (CDCl3, 250 MHz): ͳ: 3.87 [s, 6H, OMe],
3.90[s, 4H, CH2], 6.83[d, 4H, J 8.6], 7.15[d, 4H, J 8.6].
13C NMR (CDCl3, 63MHz): ͳ 41.0[CH2], 55.4[Me],
114.2[C-3], 127.8[C-2], 130.3[C-1], 159.4[C-4],
137.5[CuC], 211.8[CuS].
Crystal structure determinations
All structures were determined using Mo-KͰ ra-
˚
diation (␭ ϭ 0.71073 A wavelength).
Compound 2
Data were obtained at 293(2)K at the National
Data Collection Centre of the EPSRC at Southamp-
ton. The instrument was an Enraf Nonius Kappa
CCD area detector with an Enraf Nonius FR591 ro-
tating anode as X-ray source. The phi-omega scan
mode, filling the Ewald sphere, was employed. Data
collection, and cell refinement and data reduction
were accomplished with COLLECT10 and DENZO,11
respectively. An empirical correction for absorption
was applied by means of SORTAV.12 The structure
was solved by direct methods, SHELXS86,13 and com-
pleted and refined with SHELXL97.14 Both methoxy
groups exhibit disorder. The C and O atoms of the
MeO group on C16 are distributed over two sites:
C19A, 02A [site occupancy factor: 0.415(10)] and
C19B, O2B [site occupancy factor: 0.585(10)]. Two
occupied sites, C11A/C11B [site occupancy factors:
0.538(14)/0.462(14)], were calculated for the carbon
atom of the other MeO group, on C8. All non-H
4,5-Bis-(p-nitrobenzylthio)-1,3-dithiole-2-thione, 4
This was prepared similarly to 2 from p-
O2NC6H4CH2Cl (0.43 g, 2.5 mmol) and [NEt4]2[Zn
(dmit)2] (0.45 g, 0.63 mmol) as a red solid and was
recrystallized from CHCl3/hexane, m.p. 105-6Њ C [lit.
value9 m.p. 102Њ C].
Analysis. Found: C, 44.0; H, 2.3; N, 6.1. Calcu-
lated for C17H12N2O4S5 : C, 43.6; H, 2.6; N, 6.0%. IR
(KBr): v(CuS) 1061 cmϪ1. Vis (CH2Cl2): 374, 520
nm. 1H NMR (CDCl3, 250 MHz): ͳ: 4.00[s, 4H, CH2],
7.40[d, 4H, J 8.6], 8.17[d, 4H, J 8.6]. 13C NMR (CDCl3,
63 MHz): ͳ: 40.3 [CH2], 124.1[C-3], 129.9[C-2],
136.8[CuC], 143.2[C-1], 147.6[C-4], 209.9[CuS].

4-5-Bis(benzylthio)-1,3-dithiole-2-thione
1167
were refined anisotropically and H were placed in
calculated positions and refined with a riding model.
Compound 4
The unit cell and intensities data were collected
at the National Data Collection Centre of the EPSRC
at Cardiff at 293(2)K on a Delft Instrument FAST
diffractometer using the routines ENDEX, REFINE
and MADONL in the MADNES software17 and pro-
cessed using ABSMAD.18 Procedural details were as
described by Darr, et al.19 The asymmetric unit con-
sists of two crystallographically distinct molecules,
which constitute a dimeric structural unit and are
numbered in an identical manner but distinguished
by suffices A and B. The nonhydrogen atoms were
refined with anisotropic temperature factors and hy-
drogen atoms were allowed to ride on their attached
carbon atoms with a common isotropic temperature
factor. No absorption correction was applied.
Compound 3
Data were obtained at 298(2)K with a Nicolet
P3 4-circle diffractometer operating in ␪-2␪ mode
with variable scan rates in the range 5.33 (Ip Ͻ 150)
to 58.6 (Ip Ͼ 2500)Њ 2␪.minϪ1 where Ip is the pre-
scan intensity. The scan width was 2.4 to 2.7Њ in 2␪.
For background count correction total background
(two counts, one on either side of the Bragg angle)
and peak scan count times were equal. Nicolet P3
software15 was used for cell refinement and data col-
lection and the local program RDNIC16 for data re-
duction. No correction for absorption was applied.
The structure was solved by direct methods,
SHELXS86,13 and completed and refined with
SHELXL97.14 The asymmetric unit is a single com-
plete molecule. All non-H were refined anisotropi-
cally and H were placed in calculated positions and
refined with a riding model.
All diagrams were obtained with ORTEP-3 for
Windows20 and ORTEX.21 Crystal data and structure
refinement details are listed in Table 1. Tables 2–4
list fractional coordinates and equivalent isotropic
thermal parameters for the three compounds.
Table 1. Crystal Data and Structure Refinement
Compound
CCDC deposit no.
2
3
4
CCDC-1003/5697
CCDC-1003/5698
CCDC-1003/5699
Red
Color
Red-brown
C19H18O2S5
438.63
293(2)
Triclinic
P1
Deep-red
C18H15NO3S5
453.61
298(2)
Triclinic
P1
Chemical formula
Formula weight
Temperature, K
Crystal system
Space group
C17H12N2O4S5
468.59
293(2)
Triclinic
P1
Unit cell dimensions
˚
a (A)
5.2920(10)
10.537(2)
18.961(4)
5.292(8)
10.528(12)
19.01(2)
9.296(8)
13.993(18)
16.186(4)
˚
b (A)
˚
c (A)
Ͱ (Њ)
ͱ (Њ)
Ͳ (Њ)
102.79(3)
96.33(3)
98.67(3)
1007.9(3)
102.74(9)
96.26(1)
98.56(11)
1010(2)
106.68(3)
89.63(3)
99.38(6)
1988(33)
˚
Volume (A)
Z
2
2
4
Density (calculated), mg/m3
Absorption coefficient, mmϪ1
Diffractometer/scan
1.445
0.586
1.491
0.593
1.566
0.610
Enraf Nonius
KappaCCD area detector
2.02 to 27.44
9661
Nicolet P3 4-circle diffracto-
meter
2.02 to 25.05
3583
Delft Instrument FAST dif-
fractometer
2.22 to 24.83
7001
␾ range for data collection (Њ)
Reflections measured
Independent/observed reflections
4480 [R(int) ϭ 0.0691]/2565
[I Ͼ 2␴(I)]
4480/0/246
1.049
5582 [R(int) ϭ 0.0079]/1660
[I Ͼ 2␴(I)]
3582/0/245
0.997
4845 [R(int) ϭ 0.0954]/1194
[I Ͼ 2␴(I)]
4845/0/505
0.588
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I Ͼ 2␴(I)]
R1 ϭ 0.0758
wR2 ϭ 0.2235
R1 ϭ 0.1277
wR2 ϭ 0.2583
R1 ϭ 0.0681
wR2 ϭ 0.1302
R1 ϭ 0.1623
wR2 ϭ 0.1678
R1 ϭ 0.0570
wR2 ϭ 0.0976
R1 ϭ 0.1915
wR2 ϭ 0.1188
R indices (all data)

1168
Chohan, Howie, Wardell, and Wardell
Crystal structures
Table 2. Atomic Coordinates (ϫ 104) and Equivalent Isotropic
2
3
a
˚
Displacement Parameters (A ϫ 10 ) for 2
The atom arrangements and the numbering sys-
tem for 2–4 are shown in Figs. 1–3, respectively. Both
methoxy groups in 2 exhibit disorder. The C and O
atoms of the MeO group on C16 are distributed over
two sites: C19a, O2a and C19b, O2b. Two sites, C11a/
C11b, were calculated for the carbon atom of the
other MeO group, on C8.
The geometric parameters within the dmit
groups are similar in each of the bis(benzyl)dmit mol-
ecules, see Table 5. Compounds 2 and 3, are isostruc-
tural with the previously reported 5, but not, how-
ever, with 4. Two independent molecules, A and B,
of 4 are present in the asymmetric unit, in contrast
to only one in each of the other bis(benzyl)dmit com-
pounds. The thione groups atoms, C3uS5, are in all
cases out of the planes through the other dmit group
atoms, i.e., the CuC and the attached S atoms: the
distances the thione S atoms are out of the dmit plane
͉
x
͉
y
͉
z
͉ U(eq)a
S1
S2
S3
S4
S5
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
O1
11796(2)
12096(2)
7161(2)
7379(2)
3084(2)
9638(7)
9718(7)
5732(7)
9868(9)
5453(1)
2270(2)
4283(1)
1591(1)
2179(1)
4043(4)
2795(5)
2664(4)
6107(5)
5410(4)
4463(6)
3775(6)
4058(6)
5005(7)
5673(6)
3315(10)
2525(10)
3601(12)
1004(5)
412(5)
1517(1)
1550(1)
393(1)
393(1)
Ϫ563(1)
999(2)
72(1)
86(1)
74(1)
73(1)
81(1)
60(1)
63(1)
62(1)
79(1)
67(1)
85(2)
100(2)
88(2)
95(2)
86(2)
194(3)
79(3)
71(3)
88(2)
69(1)
105(2)
114(2)
97(2)
92(2)
83(1)
101(2)
126(4)
101(2)
126(4)
1015(2)
48(2)
2211(3)
2809(2)
2827(3)
3374(3)
3901(3)
3892(3)
3345(3)
4514(4)
4519(5)
4936(5)
1855(3)
2315(3)
3063(3)
3480(3)
3133(4)
2413(4)
1984(3)
3628(7)
4336(11)
3373(5)
4107(8)
9886(8)
7804(9)
7916(11)
10055(11)
12092(11)
12011(9)
10220(3)
8390(2)
12058(19)
10210(9)
11972(8)
12121(13)
13819(14)
15199(11)
15008(10)
13417(10)
16530(2)
16470(4)
17144(15)
17610(3)
C11Ab
C11Bb
C12
C13
C14
C15
C16
C17
C18
O2Ab
C19Ab
O2Ba
C19Bb
689(7)
111(7)
Table 3. Atomic Coordinates (ϫ 104) and Equivalent Isotropic
Ϫ725(6)
Ϫ1011(6)
Ϫ463(5)
Ϫ1175(13)
Ϫ820(2)
Ϫ1611(9)
Ϫ1191(15)
2
3
a
˚
Displacement Parameters (A ϫ 10 ) for 3
͉
x
͉
y
͉
z
͉ U(eq)a
S1
S2
S3
S4
S5
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
N1
O1
O2
C11
C12
C13
C14
C15
C16
C17
O3
C18
Ϫ1786(3)
Ϫ2090(3)
2841(3)
2625(3)
6909(3)
378(11)
281(11)
4272(11)
140(13)
124(12)
2165(13)
2177(15)
Ϫ39(18)
Ϫ2127(15)
Ϫ1981(14)
Ϫ110(2)
1670(2)
Ϫ2040(2)
Ϫ230(13)
Ϫ1969(12)
Ϫ3436(13)
Ϫ5019(14)
Ϫ5187(17)
Ϫ3730(2)
Ϫ2173(17)
Ϫ6920(12)
Ϫ7170(2)
Ϫ458(2)
2727(2)
714(2)
3408(2)
2827(2)
960(6)
2227(6)
2339(6)
Ϫ1122(6)
Ϫ418(6)
526(7)
3487(1)
3448(1)
4607(1)
4602(1)
5559(1)
3989(3)
3988(3)
4956(3)
2798(4)
2198(3)
2181(4)
1632(5)
1115(4)
1122(4)
1671(4)
541(5)
70(1)
85(1)
74(1)
71(1)
79(1)
56(2)
59(2)
60(2)
78(2)
64(2)
77(2)
92(2)
84(2)
94(2)
84(2)
118(3)
194(4)
190(4)
86(2)
66(2)
75(2)
91(2)
98(3)
114(3)
99(3)
157(3)
214(7)
a U(eq) is defined as one third of the trace of the orthogonalized
Uij tensor.
b Site occupancy factors: C11A 0.538(14): C11B 0.462(14): O2A &
C19A 0.415(10): O2B & C19B 0.585(10).
Results and discussion
1203(8)
911(8)
The bis(benzyl)-dmit compounds, 2 and 4, were
obtained from reactions of [NEt4]2[Zn(dmit)2] with
the appropriate benzyl halide. The mixed benzyl de-
rivative, 3, was obtained, with the two symmetrical
compounds, 2 and 4, from a reaction mixture con-
taining p-O2NC6H4CH2Cl and p-MeOC6H4CH2Cl:
separation of the three products was achieved using
column chromatography. All bis(benzylthio)-dmit
compounds are orange to brown colored solids, hav-
ing a weak absorption in the visible region at ca 520
nm, with a stronger absorption at ca 370 nm. There
were no significant differences in the ␭max values
for any of the bis(benzylthio)-dmit compounds pre-
pared in this study. Values of v(CuS) in the IR
spectra were in the narrow range of 1065-1055 cmϪ1.
Ϫ40(8)
Ϫ687(7)
1643(10)
2441(8)
1393(10)
3993(7)
4594(6)
5466(7)
6020(7)
5727(9)
4871(9)
4304(7)
6439(7)
6063(11)
511(5)
100(5)
3137(4)
2685(4)
2999(4)
2590(5)
1858(6)
1509(4)
1936(5)
1513(4)
772(6)
aU(eq) is defined as one third of the trace of the orthogonalized
Uij tensor.

4-5-Bis(benzylthio)-1,3-dithiole-2-thione
1169
Table 4. Atomic Coordinates (ϫ 104) and Equivalent Isotropic
2
3
a
˚
Displacement Parameters (A ϫ 10 ) for 4
͉
x
͉
y
͉
z
͉ U(eq)a
S1A
S2A
S3A
S4A
Ϫ354(3)
607(3)
1295(4)
2038(3)
2858(4)
5873(2)
3543(3)
6021(2)
4057(2)
5311(3)
5296(8)
4369(8)
5126(8)
7010(9)
7548(10)
7279(10)
7822(12)
8574(9)
8846(9)
8325(10)
9184(11)
8850(8)
9880(8)
2552(8)
2060(8)
1433(8)
988(8)
2679(2)
1994(2)
4308(2)
3774(2)
5551(2)
3250(7)
3001(7)
4601(7)
2701(9)
2122(10)
1261(10)
744(9)
1100(9)
1953(9)
2447(7)
562(8)
Ϫ207(6)
892(8)
2173(7)
2808(8)
2601(7)
3188(9)
3988(9)
4232(8)
3636(9)
4610(8)
4356(7)
5357(7)
7238(2)
7666(2)
8815(2)
9220(2)
10411(2)
8076(7)
8277(7)
9494(9)
6728(7)
5870(9)
5163(10)
4351(9)
4279(8)
4966(8)
5769(7)
3415(8)
2813(6)
3372(6)
8315(7)
9188(7)
9271(7)
10069(8)
10754(9)
10721(8)
9943(10)
11597(8)
11645(6)
12190(6)
71(1)
67(1)
82(1)
65(1)
89(1)
50(3)
51(3)
57(3)
105(5)
64(4)
80(5)
82(5)
52(4)
61(4)
58(4)
74(4)
104(4)
117(4)
61(4)
47(3)
42(3)
54(4)
56(4)
66(4)
68(4)
77(4)
106(4)
112(4)
76(1)
65(1)
82(1)
71(1)
94(1)
57(3)
55(4)
105(6)
95(5)
59(4)
73(3)
72(4)
51(3)
56(4)
57(4)
72(4)
113(4)
96(4)
56(3)
37(3)
47(3)
47(3)
48(3)
68(4)
71(4)
75(4)
105(4)
101(4)
S5A
C1A
C2A
C3A
C4A
C5A
C6A
C7A
C8A
C9A
C10A
N1A
O1A
O2A
C11A
C12A
C13A
C14A
C15A
C16A
C17A
N2A
O3A
O4A
S1B
675(10)
1009(10)
2178(11)
881(12)
300(13)
531(13)
Fig. 1. Atom arrangements and numbering system for 2. H-atoms
are omitted for clarity, as are disordered atoms, C11b, O2b, and
C19b. Probability ellipsoids drawn at 20%.
70(13)
Ϫ663(13)
Ϫ941(12)
Ϫ423(12)
Ϫ1138(12)
Ϫ942(10)
Ϫ1707(11)
Ϫ781(10)
Ϫ250(11)
781(10)
1295(11)
766(13)
1216(10)
1791(9)
2221(9)
790(10)
134(8)
Ϫ240(13)
Ϫ780(12)
1322(13)
2044(10)
1061(11)
5357(3)
4358(3)
3709(4)
2930(3)
2157(4)
4295(10)
4027(11)
2751(12)
4145(12)
4669(12)
4378(13)
4778(13)
5574(12)
5945(12)
5453(12)
5990(12)
5774(11)
6617(10)
5701(10)
5205(10)
4168(11)
3683(11)
4175(12)
5151(14)
5716(12)
3634(12)
2954(10)
3896(10)
1127(8)
4100(2)
6397(3)
3948(2)
5903(2)
4683(3)
4668(9)
5598(8)
4789(9)
2928(9)
2443(10)
2728(10)
2235(10)
1470(10)
1171(8)
1672(9)
902(10)
1224(8)
208(7)
7391(8)
7896(8)
8537(8)
8984(8)
8805(9)
8194(9)
7745(9)
9249(9)
9920(7)
8946(8)
S2B
S3B
S4B
S5B
Fig. 2. Atom arrangements and numbering system for 3. H-atoms
are omitted for clarity. Probability ellipsoids drawn at 20%.
C1B
C2B
C3B
C4B
C5B
C6B
C7B
C8B
C9B
C10B
N1B
O1B
O2B
C11B
C12B
C13B
C14B
C15B
C16B
C17B
N2B
O3B
O4B
Fig. 3. The common numbering system used for the two indepen-
dent molecules, A and B, of 4. H-atoms have been omitted for
clarity.
˚
˚
are 0.0086(2) A in 2, 0.079(4) A in 3, and 0.135(6)
˚
(molecule A) and 0.156(6) A in 4.
Conformational differences between 2, 3, and 5,
on one hand, and 4, on the other, are indicated by
the angles between the planes of the dmit group and
aryl rings: for example, the dmit plane makes angles
aU(eq) is defined as one third of the trace of the orthogonalized
Uij tensor.

1170
Chohan, Howie, Wardell, and Wardell
˚
Table 5. Selected Bond Lengths (A) and Angles (Њ) for 2–4
4
2
3
molecule A molecule B
S3UC1
S4UC2
S3UC3
S4UC3
S5UC3
C1UC2
S1UC1
S2UC2
1.732(4) 1.745(6)
1.754(4) 1.742(7)
1.707(4) 1.716(6)
1.721(4) 1.725(6)
1.653(4) 1.644(7)
1.329(6) 1.343(8)
1.752(4) 1.754(7)
1.759(4) 1.749(6)
1.832(5) 1.827(7)
1.783(7)
1.766(10)
1.770(10)
1.774(10)
1.684(10)
1.600(10)
1.331(11)
1.764(10)
1.708(11)
1.795(11)
1.820(10)
1.802(11)
1.816(11)
1.725(11)
1.723(10)
1.618(12)
1.313(12)
1.751(10)
1.685(11)
1.809(12)
1.791(11)
S1UC4
S2UC11
S2UC12
1.782(5)
S5UC3US4
S5UC3US3
C3US4UC2
C3US3UC1
S4UC2UC1
C2UC1US3
S3UC3US4
C2UC1US1
C1UC2US2
123.6(3) 123.7(4)
123.6(3) 124.0(4)
126.8(6)
126.0(6)
100.9(5)
98.9(5)
115.1(9)
115.1(8)
110.0(6)
128.6(9)
124.2(9)
123.0(8)
124.1(6)
100.3(5)
98.9(5)
112.9(9)
116.8(8)
110.8(6)
126.9(9)
126.1(9)
Fig. 4. The cell of 3 viewed down a (up into page) showing S---S
contacts, but not H-bonds. The direction of b* and c* are indicated.
Non-H-atoms are shown as 20% ellipsoids: H-atoms are omitted
for clarity.
97.0(2)
98.1(2)
97.9(3)
98.2(3)
115.9(3) 115.8(4)
116.0(3) 115.6(4)
112.8(2) 112.3(3)
126.7(3) 127.7(4)
125.4(3) 124.2(5)
i
˚
3 of 3.314(5) A [S3---S3 (symmetry operation: i: Ϫx
ϩ 1,Ϫy, Ϫz ϩ 1] link the molecules into pairs: Figure
4 illustrates the S---S interactions in 3. The equivalent
˚
S---S distance in 5 is 3.36(1) A. There are no other
of 61.17(15)Њ and 42.14(15)Њ with the aryl planes in
2, 61.1(2)Њ [p-MeOC6H4] and 42.4(2)Њ [p-O2NC6H4] in
3, in contrast to 43.1(3)Њ and 31.6(3)Њ in molecule A,
and 42.0(4)Њ and 32.8(3)Њ in molecule B of compound
4. The angles between the aryl planes, 83.88(16) and
83.9(2)Њ, in 2 and 3, respectively, are markedly differ-
ent from those in 4, 14.5(6) (molecule A) and 11.7(6)Њ
(molecule B). In 2, 3, and 5, both benzyl groups are
directed away from the dmit moiety to provide an
extended configuration, whereas in 4, only one benzyl
extends away from the dmit unit, the other is folded
back upon it. The change in conformation from the
extended form of 2, 3, and 5 to the semifolded from
of 4 is brought about by rotation of a benzyl group
about the appropriate S-CH2 bond, on average,
S---S contacts in 2, 3, and 5 less than the van der
Waals radii sum of 3.70 A.
22
˚
An intermolecular Br----Br separation of 3.65(1)
A is present in 5; this distance is at the lower end
7
˚
of the range of the sum of the van der Waals radii
22
˚
for two Br atomsUbetween 3.60 and 4.00 A. In 2,
which, as mentioned above, is isostructural with 5,
there are no intermolecular contacts less than appro-
priate van der Waals radii sums. In 3, also isostruc-
tural with 2, intermolecular contacts involving C9 and
ii
ii
˚
˚
O2ʈ [C9---O2 ϭ 3.553(14) A, H9---O2 ϭ 2.65 A, Є
C9-H9---O2ii ϭ 163.7Њ (symmetry operation: ii:
Ϫx ϩ 1,Ϫy ϩ 1, Ϫz)] occurs. While H-bonds between
aryl-H and O atoms of nitro groups are well-estab-
lished,23,24 the C---O distance in this interaction in 3
appears at the limits of a H-bonding interaction. A
slightly shorter contact involves C18 and O2iii
138.4Њ, as shown by the torsion angles in Table 6.
i
˚
Short S---S contacts in 2 of 3.320(2) A [S3---S3
˚
[3.498(13) A: (symmetry operation: iii: Ϫx ϩ 1,Ϫy ϩ
(symmetry operation: i: Ϫx ϩ 1, Ϫy ϩ 1, Ϫz] and in
Table 6. Selected Torsional Angles (Њ) in 2–4
2
C2US2UC12UC13
C1US1UC4UC5
3
C2US2UC11UC12
C1US1UC4UC5
4
178.8(4)
80.5(4)
Ϫ177.4(5)
Ϫ79.7(5)
C1US1UC4UC5
molA
mol B
molA
molB
171.2(10)
165.6(9)
Ϫ57.9(9)
Ϫ58.7(9)
C2US2UC11UC12

4-5-Bis(benzylthio)-1,3-dithiole-2-thione
1171
of the nitro group, or even to both factors: the
strongly electron-rich oxygens will result in consider-
able electrostatic repulsion for a close approach of
the two nitro groups. Either factor will provide resis-
tance to the aryl groups in 4 occupying the same space
as that taken up by the p-substituted-aryl groups in
molecules, 2, 3, and 5: hence a conformation with
a greater separation of the two aryl groups will be
preferred for 4. That 2, 3, and 5 are isostructural
indicates that individual factors, namely Br---Br in-
teractions in 5 and H-bonds in 3, if present at all,
cannot be structurally significant. Furthermore, there
is no specific interaction between the electron-rich
methoxyphenyl ring and the electron-poor nitrophe-
nyl ring in 3.
Fig. 5. The cell of 3 viewed down a (down into page) showing
S---S contacts, but not H-bonds. The direction of b* and c* are
indicated. Non-H-atoms are shown as 20% ellipsoids: H-atoms are
omitted for clarity. Representative molecules A and B are indi-
cated.
Molecules of 2, 3, and 5 are linked into molecule-
dimers by a single ring-S---ring-S contact, in contrast
to the situation in 4 in which two longer and distinct
S---S contacts, both involving exocyclic-S---thione-S
contacts, result in chains of molecules formed from
4A–4B pairs. With different molecular conforma-
tions, it is not difficult to envisage that differences in
intermolecular contacts will arise. The folding back
of a benzyl group in 4 allows more ready access to
the exocyclic-S atoms. In all cases, the individual
S---S contacts constitute at best weak interactions.
The H-bonds, involving the nitro group oxygen
atoms in 4, and to a lesser extent in 3, augment the
S---S interactions in forming the molecular assembly
in the crystalline state.
1, Ϫz)] i.e., with the methoxyl group. The fact that
the three compounds, 2, 3, and 5, are isostructural
indicates that the individual substituents have no spe-
cific role in the structural arrangements.
In contrast to the situation in 2, 3, and 5, two
distinct S---S intermolecular contacts occur in 4 at
distances less than the van der Waals radii sum (see
˚
Fig. 5). An S5A---S2B contact of 3.5116(5) A links
the two independent molecules, A and B, into a bimo-
lecular unit, which are further connected into chains,
propagated in the c direction, by S2A---S5Bi contacts
˚
(symmetry operation: i: x, y, z-1) at 3.569(5) A. There
are much more clear-cut CUH---O hydrogen bonds
present in the crystal structure of 4, see Table 7,
compared to that in 3.
Acknowledgments
Conclusions
The EPSRC X-Ray crystallography service is
thanked for obtaining the data for 2 (at Southamp-
ton) and for 4 (at Cardiff). The authors also thank
Islamia University, Pakistan for financial support
for ZHC.
The differences in the molecular structure of 4,
compared to those of 2, 3, and 5, could arise from
the greater polarity or the greater steric requirements
Table 7. Intermolecular Hydrogen Bonds in 4
˚
˚
CUH---O
d(H---O) A
D(C---O) A
[CUH---O]Њ
C10AUH10A---O4Aiii
C14AUH14A---O3Biv
C9BUH9B---O3Av
2.56
2.40
2.40
2.66
2.54
3.483(15)
3.072(15)
3.214(14)
3.484(14)
3.276(14)
175.0
128.9
145.6
148.2
136.1
C13BUH13B---O1Bvi
C14BUH14B---O2Avii
v
Note: symmetry operations: iii: Ϫx, Ϫy ϩ 1; iv: x, y Ϫ 1, z Ϫ 1; : Ϫx ϩ 1, Ϫy,
Ϫz ϩ 1; vi: Ϫx ϩ 1, y ϩ 1, Ϫz ϩ 1; vii: Ϫx, Ϫy ϩ 2, Ϫz ϩ 1.

1172
Chohan, Howie, Wardell, and Wardell
276: Macromolecular Crystallography, Part A, Carter, C.W.;
Sweet, R.M. Eds., New York & London: Academic Press,
1997; pp. 307–326.
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