Structures and properties of 1,4-dithiins and related molecules

Article abstract of DOI:10.1023/A:1013722518076

A series of organosulfur compounds was characterized by NMR, IR, mass spectroscopy, cyclic voltammetry, and chemical analyses. The crystal structures of six compounds were determined: 1,3-dithioleno[4,5-e]naphtho[2,3-b]1,4-dithiin-2,5, 10-trione (1b), P1,

Full text of DOI:10.1023/A:1013722518076

C
Journal of Chemical Crystallography, Vol. 31, No. 1, January 2001 ( 2002)
Structures and properties of 1,4-dithiins and
related molecules
Miguel A. Mendez-Rojas,(1) Satish G. Bodige,(1) Krzysztof Ejsmont,(1)
and William H. Watson(1)*
Received April 20, 2001
A series of organosulfur compounds was characterized by NMR, IR, mass spec-
troscopy, cyclic voltammetry, and chemical analyses. The crystal structures of
six compounds were determined: 1,3-dithioleno[4,5-e]naphtho[2,3-b]1,4-dithiin-2,5,
¯
˚
10-trione (1b), P1, a = 7.665(4), b = 7.997(4), c = 11.443(5) A, = 91.311(8),
=
92.516(8),
= 117.53(7) ; 6,7-dimethylbenzo[1,2-b]1,3-dithioleno[4,5-e]1,4-dithiin-
˚
2,5,8-trione (2b), P21/m, a = 3.933(1), b = 12.864(2), c = 11.943(3) A,
=
99.161(4) ; 6-phenyl-2-thioxo-6-hydrocyclopenta[2,1-b]1,3-dithioleno[4,5-e]1,4-dithiin-
˚
5,7-dione (3a), C2/c, a = 32.408(6), b = 3.8743(8), c = 27.123(5) A, = 125.171(7) ;
6-phenyl-1,3-dithioleno[4,5-e]3-pyrrolino[3,4-b]1,4-dithiin-5,7-trione (3b), P21/n, a =
˚
7.9712(9), b = 6.1976(7), c = 55.978(6) A,
= 91.096(1) ; 2,3,7,8-tetramethyl-
˚
thianthrene-1,4,6,9-tetraone (4), P21/c, a = 4.195(1), b = 17.924(5), c = 9.682(3) A,
= 98.509(5) ; 3H,6H-1,4-oxathiino[60,50-2,1]naphtho[3,4-e]1,4-oxathiin-2,7-dione (5),
˚
P21/n, a = 9.3522(7), b = 7.8782(6), c = 17.118(1) A, = 93.171(1) . Several struc-
tures exhibited significant S–S intermolecular interactions, suggesting that the molecules
might be precursors for preparing nonmetallic conductors.
KEY WORDS: S–S intermolecular interactions; quinones; maleimides.
Introduction
withdrawing and the semiquinone can be stabi-
lized to form compounds which also exhibit good
electrical conductivity.1 Cyclic-voltammetry
studies indicate that the bis-1,3-dithiolequinones
are better electron acceptors than chloranil. Previ-
ously, we reported the synthesis and characteriza-
tion of a variety of 1,3-dithiolequinones, tetrathia-
fulvalene analogues, and quinonedithiolate metal
complexes.2 4 In this paper we report the synthe-
ses, structures, and properties of several quinone
and maleimide dithiindithioles (Scheme 1).
If these compounds are to be useful precursors for
conducting solids, the important question must
be whether or not the carbonyl oxygen atoms
prevent short S–S intermolecular contacts.
Organosulfur compounds, and in particular
systems containing 1,3-dithiole rings such as
TTF, frequently are good electronic conductors
and even superconductors. The 1,3-dithiole
compounds act as electron donors, and short S–S
intermolecular contacts are important contributors
to the formation of a conduction band in the solid.
When the 1,3-dithiole ring is fused to a quinone
moiety, the molecules now become electron
(1) Department of Chemistry, Texas Christian University, Box
298860, Fort Worth, Texas.
* Towhomcorrespondenceshouldbeaddressed;e-mail:w.watson@
tcu.edu.
17
C
1074-1542/02/0100-0017/0 2002 Plenum Publishing Corporation

18
Mendez-Rojas, Bodige, Ejsmont, and Watson
Scheme 1.
Experimental
as solvent and TMS as an internal reference.
Cyclic voltammetric studies were performed on a
BAS CV-50W potentiostat using a three-electrode
microcell with a Pt disk as the working electrode,
a saturated calomel reference electrode, and a Pt
wire as auxiliary electrode. Ferrocene was added
to all samples as an internal reference, and the data
corrected to that of the normal hydrogen electrode
assuming the ferrocene couple is 0.400 V.5 Cyclic
voltammetry and UV–Vis data for compounds 1a,
1b, 2a, 2b, 3a, and 3b are given in Table 1.
Melting points (uncorrected) were deter-
mined on a Thomas-Hoover apparatus. IR spectra
were recorded on a Midac Systems FTIR at a spec-
tral resolution of 4 cm 1 (KBr pellets). Mass spec-
tra were obtained on a Finnigan quadrupole mass
1
spectrometer. H and 13C spectra were recorded
on a Varian XL300 spectrometer using CD3Cl
Table 1. Voltammetric Dataa and UV–Vis Absorption Datab for
Compounds 1a, 1b, 2a, 2b, 3a, and 3b
Compound
E1/2
Ep (irreversible)
(nm)
Synthesis
1a
1b
2a
0.34
0.36
0.27
0.60, 0.94
—
1.63, 1.23, 0.25,
0.11, 1.33
—
304, 377, 556
303, 532
304, 379, 578
1,3-Dithioleno[4,5-e]naphtho[2,3-b]1,4-dithiin-
2,5,10-trione (1b)
2b
3a
3b
0.31
—
—
296, 557
303, 396
289, 474
To 1.68 g (2.20 mmol) of [Zn(4,5-disulfanyl-
1,3-dithiole-2-thionate)2](tetraethylammonium)2
or [Zn(dmit)2](TEA)2 in acetone (20 mL)
was added 1.00 g (4.40 mmol) of 2,3-
dichloronaphthoquinone and the mixture stirred
at room temperature (rt) overnight. The solid
thione 1a was recovered by vacuum filtration
0.23, 0.75
0.49
aAll voltammetric measurements use CH3CN as solvent with 0.1 M
(n-Bu)4NClO4 as electrolyte at 293 K. All potentials are calibrated
by reference to the standard ferrocene couple and referenced to the
NHE value of 0.400 V.5
bCHCl3 used as solvent.

Organosulfur compounds
19
(1.55 g, yield >99%). The sample was recrystal-
110 (10), 88 (87), 76 (16). Anal. Calcd. for
C11H6O2S5: C, 39.90; H, 1.80. Found: C, 39.74;
H, 2.01. The reaction of the thione with mercury
acetate was identical to that described above, giv-
ing 1.48 g of black 2b (yield 99%), m.p. >355 C.
lized from CH2Cl2 yielding dark green crystals,
1
m.p. 354–355 C (lit.6 354–355 C). IR (cm ):
1663 (vs), 1586 (m), 1553 (m), 1493 (m), 1385
(w), 1275 (vs), 1134 (m), 1073 (vs), 794, 706,
1
1
635, 505. H NMR (CDCl3): 8.16 (dd, 2p-H),
IR (cm ): 1682 (2), 1651 (s), 1610 (sh), 1568 (s),
7.80 (dd, 2o-H). MS (m/z) (%): 352 (46, M+),
276 (20), 104 (24), 88 (100), 76 (87), 74 (11).
Anal. Calcd. for C13H4O2S5: C, 44.30; H, 1.14.
Found: C, 44.48; H, 0.99. The 1.55 g (4.40 mmol)
of the thione 1a was suspended in a mixture of
chloroform (40 mL) and acetic acid (15 mL) and
refluxed overnight with 3.22 g (10.1 mmol) of
mercuric acetate. Solid HgS and unreacted mer-
curic acetate were removed by vacuum filtration.
The organic phase was washed twice with 10 mL
portions of water and then dried. The solvent was
evaporated and the solid product recrystallized
from CH2Cl2–isooctane yielding 0.56 g of black
1b, m.p. 250–252 C (lit.6 250–252 C) (yield
1506 (w), 1379 (w), 1265 (s), 1171 (s), 1117 (w),
1088, 1011, 907, 864, 777, 756, 704, 550, 469,
422. 1H NMR (CDCl3): 2.09 (2, 6H). MS (m/z)
(%): 314 (75, M+), 286 (60), 212 (31), 136 (32),
122 (10), 97 (38), 84 (100), 75 (21), 69 (87). Anal.
Calcd. for C11H6O3S4: C, 42.02; H, 1.92. Found:
C, 42.03, H, 1.78.
6-Phenyl-2-thioxo-1,3-dithioleno[4,5-e]
3-pyrrolino[3,4-b]1,4-dithiin-5,7-dione (3a)
To 0.857 g (3.54 mmol) of 2,3-dichloro-
N-phenyl maleimide dissolved in acetone
(30 mL) was added 1.35 g (1.77 mmol) of
[Zn(dmit)2](TEA)2 and the mixture stirred at rt
overnight. The green precipitate was recovered
by vacuum filtration yielding 1.12 g of the
thione 3a (crude yield 99.2%). The product
was recrystallized from dichloromethane, giving
small dark green needles, m.p. 225 C (dec.). IR
1
38%). IR (KBr) (cm ): 1661 (vs), 1649 (sh),
1586 (m), 1557 (m), 1400 (w), 1275 (vs), 1134
(m), 903, 853, 795, 706, 636. 1H NMR (CDCl3):
8.16 (dd, 2p-H), 7.80 (dd, 2o-H). MS (m/z)
(%): 336 (52%, M+), 307 (44), 263 (13), 232
(17), 188 (13), 144 (14), 132 (37), 109 (82), 92
(11), 88 (80), 76 (100), 75 (13), 74 (21). Anal.
Calcd. for C13H4O3S4: C, 46.41; H, 1.20. Found:
C, 46.18; H, 1.16.
1
(cm ): 1768 (w), 1721 (vs), 1601 (m), 1499 (2),
1387 (s), 1202 (w), 1109 (sh), 1087 (vs), 897,
883, 808, 779, 756, 725, 681, 633, 577, 512, 496.
1H NMR (CDCl3): 7.47 (dd, 1H), 7.32 (d, 2H),
7.26 (d, 2H). MS (m/z) (%): 367 (100, M+), 323
(25), 291 (8), 247 (9), 159 (22), 119 (11), 100
(15), 88 (97), 76 (16), 64 (16). Anal. Calcd. for
C13H5O2S5N: C, 42.49; H, 1.37 N, 3.81. Found:
C, 41.03; H, 1.40; N, 3.60.
6,7-Dimethylbenzo[1,2-b]1,3-dithioleno[4,5-e]
1,4-dithiin-2,5,8-trione (2b)
To 1.40 g (4.77 mmol) of 2,3-dibromo-5,6-
dimethylbenzoquinone in 10 mL of acetone was
added 1.82 g of [Zn(dmit)2](TEA)2 (2.38 mmol)
and the mixture stirred at rt overnight. The orig-
inal orange solution turned green, and a precip-
itate formed immediately. The solid thione 2a
was recovered by vacuum filtration (1.57 g, yield
6-Phenyl-1,3-dithioleno[4,5-e]3-pyrrolino
[3,4-b]1,4-dithiin-2,5,7-trione (3b)
1
>99%), m.p. >355 C. IR (cm ): 2988 (w), 1643
The conversion of the thione 3a to the 3b was
identical to the procedure above, yielding 1.16 g
(yield, 99%)ofblackcrystals, m.p. 290–293 C. IR
(s), 1572 (w), 1458 (vs), 1400 (m), 1277 (w), 1182
(s), 1165 (s), 1080 (vs), 1069 (sh), 1032 (m), 1007,
895, 791.1H NMR (CDCl3): 2.09 (s, 6H). MS
(m/z) (%): 330 (100, M+), 286 (14), 254 (17),
1
(cm ): 1711 (vs), 1607 (w), 1505 (w), 1402 (w),
1115 (m), 1071 (w), 891 (w), 791 (w), 748 (w),

20
Mendez-Rojas, Bodige, Ejsmont, and Watson

Organosulfur compounds
21
Table 4. Atomic Coordinates (104) and Equivalent Isotropic
727 (w), 685 (w). 1H NMR (CDCl3): 7.47 (dd,
1H), 7.32 (d, 2H), 7.26 (d, 2H). MS (m/z) (%): 353
(16), 352 (15), 351 (87, M+), 325 (13), 324 (11),
322 (67), 247 (21), 171 (12), 159 (21), 129 (11),
120 (17), 119 (62), 100 (19), 91 (28), 90 (11), 88
(100), 84 (13), 77 (10), 76 (29), 64 (27), 63 (12).
Anal. Calcd. for C13H5NO3S4: C, 44.42; H, 1.43.
Found: C, 44.20; H, 1.55.
3
2
˚
Displacement Parameters (10 A ) for 2b
a
Atom
x
y
z
Ueq
S(1)
S(2)
O(1)
C(1)
C(4)
C(5)
C(3)
C(2)
O(3)
C(6)
4531(2)
2379(2)
1022(5)
737(6)
2960(7)
3723(5)
1178(6)
2429(5)
519(7)
6209(1)
6343(1)
5449(2)
6388(2)
6313(2)
6987(2)
6977(2)
6982(2)
7500
9224(1)
11512(1)
7074(2)
7091(2)
5176(2)
10372(2)
6123(2)
8104(2)
13139(2)
12247(3)
29(1)
29(1)
41(1)
25(1)
34(1)
24(1)
24(1)
22(1)
42(1)
29(1)
2,3,7,8-Tetramethylthianthrene-1,4,6,9-
tetraone (4)
1534(9)
7500
aUeq is defined as one-third of the trace of the orthogonalized
Ui j tensor.
Compound 4 was obtained as side reaction
in the formation of metal tetrathiolate complexes.
To 0.47 g (6.85 mmol) of ammonium sulfide dis-
solved in 10 mL of methanol and 1 mL of water
at 70 C (dry ice/acetone) 1.0 g (3.42 mmol)
of 2,3-dibromo-5,6-dimethyl-benzoquinone in
20 mL of methanol was added. The mixture was
stirred for 1 h under an inert atmosphere (N2).
The initial yellow solution turns purple during this
time. The mixture was warmed to 0 C , and at this
point the purple color fades and a dark green sus-
pension forms almost immediately. NiCl2 6H2O
(0.246 g, 1.04 mmol) is added and stirred for 1 h,
followed by the addition of tetrabutylammonium
Table 5. Atomic Coordinates (104) and Equivalent Isotropic
3
2
Table 3. Atomic Coordinates (104) and Equivalent Isotropic
Displacement Parameters (10 A ) for 3a
˚
3
2
˚
Displacement Parameters (10 A ) for 1b
a
Atom
x
y
z
Ueq
a
Atom
x
y
z
Ueq
S(1)
S(2)
S(3)
S(4)
2669(1)
1912(1)
2564(1)
3483(1)
1493(1)
3432(1)
4425(1)
4055(1)
3577(1)
3287(1)
2535(1)
1961(1)
2840(1)
3584(1)
4084(1)
4459(1)
4921(1)
5301(1)
5221(1)
4756(1)
4372(1)
616(2)
285(2)
648(1)
909(1)
2061(1)
2091(1)
1593(1)
299(1)
2068(1)
1168(1)
764(1)
1027(1)
1156(1)
1523(1)
1694(1)
1558(1)
1659(1)
1089(1)
1542(1)
1456(1)
928(2)
26(1)
25(1)
25(1)
28(1)
38(1)
32(1)
35(1)
24(1)
24(1)
21(1)
21(1)
24(1)
21(1)
22(1)
25(1)
25(1)
31(1)
39(1)
42(1)
40(1)
31(1)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
O(1)
O(2)
O(3)
S(1)
2086(4)
2291(4)
954(4)
9299(4)
8940(4)
7387(4)
5935(4)
6287(4)
4967(5)
5256(5)
6844(5)
8171(5)
7893(4)
10565(4)
11685(5)
9005(5)
10668(3)
4514(3)
12556(4)
10644(1)
12699(1)
9206(1)
6743(1)
9530(3)
8273(3)
7662(3)
8197(3)
9433(3)
9969(3)
11132(3)
11770(3)
11246(3)
10076(3)
6266(3)
4196(3)
5671(3)
10080(2)
7620(2)
3342(2)
7736(1)
5562(1)
4241(1)
6226(1)
25(1)
25(1)
27(1)
27(1)
26(1)
31(1)
33(1)
34(1)
29(1)
24(1)
27(1)
40(1)
30(1)
33(1)
39(1)
61(1)
30(1)
36(1)
39(1)
40(1)
3703(2)
3754(2)
2355(2)
1207(5)
4809(5)
1731(6)
262(7)
831(4)
S(5)
1105(4)
2731(4)
2980(4)
1590(4)
50(4)
O(1)
O(2)
N(1)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
848(7)
936(7)
305(4)
3673(4)
3183(5)
2374(4)
3380(3)
1938(3)
3312(4)
4500(1)
4525(1)
1642(1)
1205(1)
2154(7)
2524(7)
2460(7)
3188(8)
1662(7)
317(7)
262(8)
S(2)
S(3)
S(4)
1464(8)
2745(8)
2904(7)
480(1)
561(1)
aUeq is defined as one-third of the trace of the orthogonalized
Ui j tensor.
aUeq is defined as one-third of the trace of the orthogonalized
Ui j tensor.

22
Mendez-Rojas, Bodige, Ejsmont, and Watson
Table 6. Atomic Coordinates (104) and Equivalent Isotropic
Table 7. Atomic Coordinates (104) and Equivalent Isotropic
3
2
3
2
˚
˚
Displacement Parameters (10 A ) for 3b
Displacement Parameters (10 A ) for Compound 4
a
a
Atom
x
y
z
Ueq
Atom
x
y
z
Ueq
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
10037(10)
9866(10)
9621(10)
8471(11)
8805(10)
9036(10)
8618(10)
9249(11)
9864(13)
9868(16)
9231(16)
8613(14)
8600(13)
3685(10)
4034(10)
3753(11)
3303(11)
4541(10)
4842(10)
5090(10)
4401(10)
3751(12)
3734(13)
4364(15)
5012(15)
5034(13)
9260(8)
55(16)
485(14)
130(14)
1090(2)
1349(2)
1817(2)
2254(2)
1835(2)
1370(2)
1123(2)
710(2)
604(2)
359(2)
220(2)
325(2)
30(2)
27(2)
27(2)
35(2)
30(2)
26(2)
30(2)
36(2)
45(3)
59(3)
70(4)
61(4)
49(3)
29(2)
27(2)
31(2)
30(2)
28(2)
25(2)
30(2)
30(2)
36(2)
44(3)
59(3)
55(3)
41(3)
32(2)
29(2)
41(2)
41(2)
51(2)
39(2)
36(2)
46(2)
32(1)
37(1)
37(1)
36(1)
38(1)
34(1)
36(1)
30(1)
S(1)
O(1)
O(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
3539(2)
6414(6)
825(6)
6323(7)
7473(7)
9832(7)
10717(8)
2581(7)
199(8)
4221(1)
2960(1)
4752(1)
4246(2)
3478(2)
3356(2)
2552(2)
5171(2)
5297(2)
6058(2)
6119(2)
8934(1)
10133(2)
6758(2)
10479(3)
10870(3)
12151(3)
12447(4)
8721(3)
7446(3)
7041(3)
5698(3)
46(1)
60(1)
61(1)
40(1)
42(1)
45(1)
60(1)
40(1)
43(1)
44(1)
60(1)
59(17)
1762(15)
2363(13)
3166(15)
1878(18)
3710(20)
3880(20)
2270(30)
390(30)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
N(1)
N(2)
O(1)
O(2)
O(3)
O(4)
O(5)
O(6)
S(1)
926(7)
3206(8)
aUeq is defined as one-third of the trace of the orthogonalized
Ui j tensor.
210(20)
571(2)
5097(15)
5362(14)
4804(15)
5633(14)
6701(14)
7224(14)
8306(16)
7250(15)
9152(16)
9450(20)
7860(20)
5990(20)
5661(18)
1639(13)
6908(12)
1619(11)
4811(12)
411(13)
3626(11)
9974(11)
5585(12)
1211(4)
1835(4)
2341(4)
3811(4)
3359(4)
3573(4)
7782(4)
1096(2)
1357(2)
1823(2)
2283(2)
1863(2)
1393(2)
1159(2)
731(2)
638(2)
391(2)
244(2)
341(2)
1
IR (cm ): 1645 (s), 1559 (s), 1437 (w), 1383
(w), 1281 (m), 1192 (s), 1090 (w), 772 (w), 702
(w). H NMR: 2.03 (s, 12H). Anal. Calcd. for
C16H12O4S4: C, 57.81; H, 3.64. Found: C, 57.71;
H, 3.86.
1
586(2)
966(1)
985(1)
Table 8. Atomic Coordinates (104) and Equivalent Isotropic
3
2
˚
Displacement Parameters (10 A ) for Compound 5
4394(8)
10719(8)
7862(8)
8179(9)
2964(8)
5803(8)
2905(9)
10703(3)
9589(3)
7812(3)
1009(1)
1072(1)
2458(1)
1001(1)
1123(1)
2486(1)
1569(1)
2064(1)
2102(1)
1619(1)
1555(1)
2068(1)
2150(1)
1659(1)
a
Atom
x
y
z
Ueq
S(1)
S(2)
2636(1)
70(1)
2402(1)
1940(1)
914(2)
1295(2)
1051(2)
1460(2)
326(2)
6558(1)
8374(1)
9297(2)
5804(2)
6734(2)
8353(2)
7092(2)
7993(2)
7166(2)
7916(2)
8464(2)
6772(2)
10360(2)
7229(3)
8078(3)
8186(3)
6887(2)
9366(3)
4768(2)
5737(3)
10710(1)
11679(1)
10676(1)
9033(1)
9476(1)
10313(1)
10252(1)
9508(1)
9079(1)
10682(1)
9119(1)
8280(1)
11718(1)
7930(1)
8349(1)
11945(1)
9843(1)
11470(1)
8844(1)
9210(1)
44(1)
47(1)
41(1)
43(1)
34(1)
34(1)
33(1)
32(1)
33(1)
35(1)
39(1)
41(1)
64(1)
48(1)
46(1)
48(1)
45(1)
44(1)
71(1)
46(1)
O(1)
O(4)
C(14)
C(7)
C(11)
C(6)
C(1)
C(10)
C(5)
C(2)
O(2)
C(3)
C(4)
C(9)
C(12)
C(8)
O(3)
C(13)
S(2)
S(3)
S(4)
S(5)
S(6)
S(7)
S(8)
8484(3)
3462(3)
2777(3)
4455(3)
87(2)
2699(2)
490(2)
5608(3)
8373(4)
aUeq is defined as one-third of the trace of the orthogonalized
Ui j tensor.
3533(2)
1701(2)
2811(2)
1818(2)
3786(2)
2652(2)
4103(2)
3348(2)
iodide (0.764 g, 2.07 mmol) with stirring for an
additional hour. A dark greenish black precipitate
was recovered by vacuum filtration and recrys-
tallized from chloroform, yielding 0.274 g (24%
yield) of small green-black plates, m.p. >330 C.
aUeq is defined as one-third of the trace of the orthogonalized
Ui j tensor.

Organosulfur compounds
23
˚
Table 9. Selected Bond Distances (A) and Angles (deg) for Compounds 1b, 2b, 3a and 3b (3ba and 3bb Indicate Two
Independent Molecules)
1b
2b
3a
3b
3b
b
a
Bond distance
C(1) O(1)
C(1) C(2)
C(2) S(1)
C(2) C(6)
S(1) C(3)
C(3) S(2)
C(3) C(5)
S(2) C(4)
1.220(3)
1.490(4)
1.760(3)
1.342(4)
1.760(3)
1.752(3)
1.328(4)
1.785(4)
1.194(4)a
1.781(4)
1.741(3)
1.756(3)
1.757(3)
1.494(4)
1.213(3)
1.213(3)
1.495(3)
1.763(2)
1.334(5)
1.767(2)
1.747(2)
1.319(5)
1.785(2)
1.196(4)a
—
1.204(3)
1.491(4)
1.737(3)
1.338(3)
1.770(3)
1.741(3)
1.351(3)
1.739(3)
1.773(3)b
1.739(3)
1.738(3)
1.773(3)
1.734(3)
1.503(4)
1.198(3)
1.204(7)
1.500(7)
1.730(5)
1.330(7)
1.770(6)
1.747(5)
1.332(8)
1.783(6)
1.201(7)a
1.776(6)
1.746(6)
1.767(5)
1.733(6)
1.506(7)
1.197(7)
1.194(7)
1.502(7)
1.739(5)
1.329(7)
1.769(5)
1.748(5)
1.342(8)
1.784(6)
1.203(7)a
1.780(6)
1.750(5)
1.768(6)
1.730(5)
1.501(7)
1.193(6)
C(4)
X
C(4) S(3)
S(3) C(5)
C(5) S(4)
S(4) C(6)
C(6) C(7)
C(7) O(2)
—
—
—
—
—
Bond angle
O(1) C(1) C(2)
C(1) C(2) S(1)
S(1) C(2) C(6)
C(1) C(2) C(6)
C(2) S(1) C(3)
S(1) C(3) C(5)
C(3) C(5) S(4)
C(5) S(4) C(6)
C(2) C(6) S(4)
C(3) S(2) C(4)
S(2) C(4) S(3)
S(4) S(3) C(5)
S(3) C(5) C(3)
120.3(2)
119.5(2)
126.8(3)
127.2(5)
127.0(5)
113.3(2)
124.9(2)
121.6(3)
99.0(1)
124.3(3)
125.6(3)
98.7(2)
124.5(2)
95.8(2)
112.3(2)
96.0(2)
114.9(2)
124.3(8)
120.8(1)
98.5(1)
124.5(8)
—
119.8(2)
131.3(2)
108.9(2)
98.3(1)
130.0(2)
130.5(2)
98.9(1)
131.8(2)
97.3(1)
112.6(2)
97.4(1)
120.8(4)
130.3(4)
108.9(5)
97.9(3)
129.8(4)
129.1(4)
97.9(3)
130.8(4)
95.6(3)
112.4(3)
96.5(3)
121.5(4)
129.7(4)
108.7(5)
98.5(3)
129.6(4)
129.0(4)
98.5(3)
131.3(4)
96.5(3)
112.2(3)
96.4(3)
—
—
95.2(1)
112.9(2)
—
118.3(9)
123.5(1)
—
118.1(3)
124.2(3)
113.2(2)
119.2(3)
116.3(2)
123.6(2)
119.7(2)
126.3(3)
116.9(4)
123.6(5)
120.3(4)
126.7(5)
117.7(4)
123.4(5)
119.3(4)
127.1(5)
S(2) C(4)
X
S(4) C(6) C(7)
O(2) C(7) C(6)
—
aX = O.
bX = S.
3H,6H-1,4-oxathiino[60,50-2,1]naptho[3,4-e]
1,4-oxathiin-2,7-dione (5)
for 1 h. The solution was cooled to 25 C and 8 mL
of acetic anhydride was added. After 30 min the
solution was cooled to 0 C and the precipitate was
filtered, washed with ethanol, and air-dried, yield-
ing 2.45 g of 13 (yield 80.6%), m.p. 276–277 C.
The physical properties agree with literature
values.7
Thiolacetic acid (3.2 mL) was added at 40 C
with stirring to 10 mL pyridine. To this solution
2.27 g (10 mmol) of 2,3-dichlorobenzoquinone
was added and the temperature raised to 80 C

24
Mendez-Rojas, Bodige, Ejsmont, and Watson
˚
˚
Table 10. Selected Bond Distances (A) and Angles (deg) for
Compound 4
Table 11. Selected Bond Distances (A) and Angles (deg) for
Compound 5
Bond distance
Bond distance
C(1) C(2)
C(1) S(1)
C(1) C(5a)
C(2) O(1)
C(2) C(3)
C(3) C(7a)
S(1) C(5)
C(5) C(6)
C(6) C(7)
C(6) O(2)
1.489(4)
1.757(3)
1.342(4)
1.214(4)
1.484(4)
1.348(4)
1.754(3)
1.486(5)
1.478(5)
1.223(4)
C(1) C(6)
C(1) C(14)
C(6) C(7)
C(7) C(10)
C(7) O(1)
O(1) C(8)
C(8) O(2)
C(8) C(9)
C(9) S(2)
S(2) C(10)
C(10) C(11)
C(11) C(14)
C(11) S(1)
S(1) C(12)
C(12) C(13)
C913) O(3)
C(13) O(4)
C(14) O(4)
1.415(3)
1.418(3)
1.423(3)
1.369(3)
1.393(2)
1.366(2)
1.198(2)
1.485(3)
1.758(2)
1.805(2)
1.418(3)
1.370(2)
1.756(2)
1.803(2)
1.488(3)
1.193(2)
1.368(2)
1.398(2)
Bond angle
C(1) C(2) C(3)
C(1) C(2) O(1)
C(3) C(2) O(1)
C(2) C(1) C(5a)
C(2) C(1) S(1)
C(1) S(1) C(5)
S(1) C(1) C(5a)
S(1) C(5) C(6)
C(5) C(6) C(7)
C(5) C(6) O(2)
C(7) C(6) O(2)
119.9(3)
118.7(3)
121.4(3)
120.2(3)
110.0(2)
100.8(1)
129.7(3)
111.1(2)
120.7(3)
118.0(3)
121.3(3)
Bond angle
C(7) O(1) C(8)
O(1) C(8) O(2)
O(1) C(8) C(9)
O(2) C(8) C(9)
C(8) C(9) S(2)
C(9) S(2) C(10)
S(2) C(10) C(7)
O(1) C(7) C(10)
C(10) C(11) C(14)
S(1) C(11) C(14)
C(11) C(14) O(4)
S(1) C(12) C(13)
C(12) C(13) O(3)
O(3) C(13) O(4)
C(12) C(13) O(4)
C(13) O(4) C(14)
123.1(2)
117.1(2)
117.0(1)
125.9(2)
110.3(1)
95.46(9)
120.8(2)
122.7(2)
119.4(2)
120.5(1)
122.4(2)
109.7(1)
126.4(2)
117.2(2)
116.4(2)
122.7(2)
X-ray analysis
X-ray data for compounds 1b, 2b, 3a, 3b,
4, and 5 were collected at 213 K on a Bruker
SMART 1000 diffractometer using Mo K radia-
tion. Because of a long unit cell dimension in com-
pound3b, thedetectorwasmovedfromthenormal
5-cm distance to 7 cm. The frames were integrated
with the Saint software package8 using a narrow-
frame integration algorithm, and the structures
were solved and refined using SHELXTL.9 All
structures were checked using the PLATON10 pro-
gram package. The positions of hydrogen atoms
were found in difference maps or were calcu-
lated. Table 2 contains crystal and refinement
data for all compounds. Atomic coordinates for
all compounds are given in Tables 3–8, while
selected bond distances and angles are given in
Tables 9–11.
and 2b exhibit a reversible one-electron wave at
E1/2 0.36and 0.31Vrespectively, whilethe
=
thione-quinone derivatives 1a and 2a exhibit irre-
versible processes in addition to reversible waves
at 0.34 and 0.27 V. The E1/2 values for the oxo
derivatives are slightly more negative than those
of the corresponding thiones. Benzoquinone gives
two one-electron waves at 0.50 and 1.33 V
while the more easily reduced tetrachlorbenzo-
quinone is shifted to +0.06 and 0.82 V. The
sulfur atom does not shift the one-electron reduc-
tion significantly, but it leads to a number of irre-
versible side reactions. Electrocrystallization will
Discussion
The cyclic voltammetry data in Table 1 in-
dicate that the two oxo-quinone derivatives 1b

Organosulfur compounds
25
Fig. 1. Packing diagram for compound 1b.
be attempted with the voltage maintained slightly
more negative than Ep for the anodic wave. Both
maleimide compounds 3a and 3b exhibit only ir-
reversible processes at all scan rates. Compounds
1b and 2b exhibit two absorption maxima in the
UV–Vis region (Table 1) while an additional ab-
sorption band around 378 nm is observed for the
thiones 1a and 2a. Both the thione 3a and the oxo-
analogue 3b exhibit two absorption bands.
Packing diagrams of compounds 1b, 2b, 3a,
and 3b are shown in Figs. 1–4. The four molecules
are folded by 42.3 (1) (1b), 52.9(1) (2b), 4.4(1)
(3a), 18.3(3) (3b), and 19.7(3) (3b0) along the
tal structures the molecular entities on either side
----
of this S S axes are planar except for the N-
phenyl rings which are twisted out of the plane
of the maleimide ring by 53.4(2) in 3a and by
53.6(3) and 53.2(3) in 3b.
Compound 1b (Fig. 1) exhibits two in-
termolecular S–O interactions smaller than the
˚
sum of van der Waals (vdv) radii ( 3.30 A),
0
0
˚
----
----
S(1) O(2) = 3.048(3) A and S(2) O(2) =
˚
3.264(3) A. There are no short S–S interactions
observed. The molecules are well-packed, lying
nestled in vertical columns with centers of grav-
˚
ity separated by 3.566(3) A. Intracolumn inter-
----
S
S axes of the dithiin six-membered rings. A
actions are weak and there are no two- or three-
dimensional networks.
density functional calculated geometry for struc-
ture 1 gave a folding angle of 37.9 and a value of
0.7 for 3. The quinone oxygen atoms in 1 are cal-
culated to be out of the phenyl plane by 6.0 while
the oxygen atoms in 3 are out of the plane by
0.9 . The maleimide six-membered dithiin moi-
eties may be more planar because of the smaller
repulsion from the carbonyl lone pairs. In the crys-
Compound 2b (Fig. 2) exhibits three sulfur
intermolecular interactions at approximately the
0
˚
----
˚
sum of the vdv radii, S(1) S(1 ) = 3.610(2) A,
0
0
----
----
S(1) S(2 ) = 3.656(2) A, and S(2) O(1 ) =
˚
3.258(2) A. The molecules pack in nestled
columns along the short axis, with centroids of the
˚
planes separated by 3.993(2) A in this direction.

26
Mendez-Rojas, Bodige, Ejsmont, and Watson
Fig. 2. Packing diagram for compound 2b.
0
˚
----
----
Compound 3a (Fig. 3) is potentially the
contacts: S(1) S(4) = 3.562(2) A, S(4) S(8)
0
˚
˚
----
----
= 3.572(2) A, S(5) S(6) = 3.561(2) A, S(2)
----
˚
most interesting compound with three S S and
0
˚
----
----
two S O distances significant0ly shorter than
O(3) = 2.936(5) A, S(6) O(6) = 3.278(5) A,
0
˚
˚
----
----
the sum of 0vdv radii: S(1) S(1) = 3.353(1) A,
and S(7) O(6) = 3.165(5) A. These interac-
tions form a linear connectivity throughout the
structure.
0
˚
A,
----
----
S(3) S(3) = 3.276(1)
S(3) S(5) =
0
˚
˚
˚
----
3.438(1) A, S(1) O(1) = 3.208(3) A, and
0
˚
0
----
----
S(2) O(1 ) = 3.203(3) A. The S(2) S(3) =
Because the maleimide structures 3a and 3b
are nearly planar and exhibit significantly shorter
S–S interactions, they may prove useful in the
preparation of conducting charge transfer com-
plexes or electrocrystallized ionic species. Re-
placement of the phenyl ring by donor and ac-
ceptor groups is being investigated currently.
In compound 4 (Fig. 5) the three six-
3.623(1) A is approximately the sum of the vdv
radii. The molecules are packed canted to the
short axis, with the short interactions occurring
between stacks forming one-dimensional ribbons
running through the structure. The interactions
along the stacks exceed the vdv contacts for the
S and O atoms.
Compound 3b (Fig. 4) has one axis of
56.45(3) A with two independent molecules
per cell. There are three S–S and three S–O
interactions slightly smaller than the sum of vdv
membered rings are completely planar (
˚
=
p
˚
.007 A), with the oxygen atoms out of the plane
˚
by 0.008(2)–0.045(2) A and the methyl groups by
˚
0.045(4)–0.071(3) A. There are no significant S–S

Organosulfur compounds
27
Fig. 3. Packing diagram for compound 3a.
Fig. 4. Packing diagram for compound 3b. Part of the central column has been removed for
clarity.
Fig. 5. Thermal ellipsoid plot for compound 4. Thermal ellipsoids are drawn
at the 35% probability level.

28
Mendez-Rojas, Bodige, Ejsmont, and Watson
metallic conductors. Since the dithiin molecules
tend to accept electrons and TTF derivatives do-
nate electrons, the formation of charge transfer
salts is under investigation currently. This study
indicates that S–S interactions might be expected
in spite of the quinone and maleimide oxygen
atoms. Further investigations into this series have
been stimulated by the recent report of supercon-
ductivity in a dithian system.13
Acknowledgment
Fig. 6. Thermal ellipsoid plot of compound 5. Ellipsoids are
We thank the Robert A. Welch Foundation
(P-0074) and the TCU Research Foundation for their
financial support.
drawn at the 35% probability level.
orS–Ointermolecularinteractions. Theclosestin-
termolecular centroid approach is 3.723(2) A.
˚
References
In compound 5 (Fig. 6) the two hetero-
cyclic rings adopt almost perfect screw-boat
conformations.11 One S atom is above and the
other below the plane of the benzene ring. The
two benzene rings are planar. There are no short
intermolecular S or O interactions of interest.
Although the metallic behavior of a neutral
1. Yamashita, Y.; Suzuki, T.; Saito, G.; Mukai, T. J. Chem. Soc.,
Chem. Commun. 1986, 1489.
2. Watson, W.H.; Eduok, E.E.; Kashyap, R.P.; Krawiec, M.
Tetrahedron 1993, 49, 3035.
3. Sun, D.; Krawiec, M.; Watson, W.H. J. Chem. Cryst. 1997, 27,
515.
4. Eduok, E.E.; Krawiec, M.; Buisson, Y.-S.L.; O’Conner, C.J.;
Sun, D.; Watson, W.H. J. Chem. Cryst. 1996, 26, 621.
5. Gagne, R.R.; Koval, C.A.; Lisensky, G.C. Inorg. Chem. 1980,
19, 2854.
6. Kniess, T.; Mayer, R.Z. Naturforsch. 1996, 51, 901.
7. Oediger, H.; Joop, N. Justus Liebigs Ann. Chem. 1972, 758, 1.
8. SAINT, Version 6.02; Bruker Analytical X-ray Systems, Inc.:
Madison, WI, 1997–1999.
9. SHELXTL, Version 5.1; Bruker Analytical X-ray Systems, Inc.:
Madison, WI, 1998.
10. Spek, A.L. Acta Crystallogr. 1982, 29, 203.
11. Boyens, J.C.A. J. Cryst. Mol. Struct. 1978, 8, 317.
12. Tanaka, H.; Okano, Y.; Kobayashi, H.; Suzuki, W.; Kobayashi,
A. Science 2001, 291, 285.
13. Yamada, J.; Watanabe, M.; Akutsu, H.; Nakatsuji, S.;
Nishikawa, H.; Ikemoto, I.; Kikuchi, K. J. Am. Chem. Soc.,
in press.
molecular species has been reported recently,12
combinations of ionic species or charge-transfer
complexes usually are necessary for high electri-
cal conductivity. In many of these species S–S or
Se–Se intermolecular interactions lead to the for-
mation of conduction bands. The present study
indicates that the dithiin molecules with quinone
functionalities are capable of packing with short
S–S intermolecular interactions and may be suit-
able vehicles for preparing ionic or charge transfer