Unsaturated thiacrown ethers: Synthesis, physical properties, and formation of a silver complex

Article abstract of DOI:10.1021/ja0102742

The 6-, 9-, 12-, 15-, 18-, 21-, 24-, and 27-membered unsaturated thiacrown ethers 1-8 were formed by reaction of cis-1,2-dichloroethylene with sodium sulfide in acetonitrile. Crystal structures of 4-8 were determined by X-ray crystallography, and it was found that all sulfur atoms of 5-8 direct to the inside of the ring (endodentate). All of the ORTEP drawings show that there are cavities in these molecules, and the cavity sizes in 4-8 were 1.76, 2.34, 3.48, 4.43, and 5.36 A, respectively. The UV spectra of 4-8 showed absorption maximums at the range of 255-276 nm in acetonitrile, and the absorption maximums of 4-8 were found to shift to longer wavelengths by changing the solvent from acetonitrile to cyclohexane. The cyclic voltammograms of 4-8 indicate that the larger unsaturated thiacrown ethers were oxidized more easily than the smaller systems, and unsaturated thiacrown ethers were oxidized more easily than corresponding saturated systems. The reaction of 4 with silver trifluoroacetate in acetone afforded the colorless complex Ag¹(C₂H₂S)₅(CF₃COO) 9. The crystal structure of 9 was determined by X-ray analysis, and it was found that three of the five sulfur atoms bonded to the silver atom.

Full text of DOI:10.1021/ja0102742

11534
J. Am. Chem. Soc. 2001, 123, 11534-11538
Unsaturated Thiacrown Ethers: Synthesis, Physical Properties, and
Formation of a Silver Complex
Takahiro Tsuchiya, Toshio Shimizu,* and Nobumasa Kamigata*
Contribution from the Department of Chemistry, Graduate School of Science,
Tokyo Metropolitan UniVersity Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan
ReceiVed January 31, 2001
Abstract: The 6-, 9-, 12-, 15-, 18-, 21-, 24-, and 27-membered unsaturated thiacrown ethers 1-8 were formed
by reaction of cis-1,2-dichloroethylene with sodium sulfide in acetonitrile. Crystal structures of 4-8 were
determined by X-ray crystallography, and it was found that all sulfur atoms of 5-8 direct to the inside of the
ring (endodentate). All of the ORTEP drawings show that there are cavities in these molecules, and the cavity
sizes in 4-8 were 1.76, 2.34, 3.48, 4.43, and 5.36 Å, respectively. The UV spectra of 4-8 showed absorption
maximums at the range of 255-276 nm in acetonitrile, and the absorption maximums of 4-8 were found to
shift to longer wavelengths by changing the solvent from acetonitrile to cyclohexane. The cyclic voltammograms
of 4-8 indicate that the larger unsaturated thiacrown ethers were oxidized more easily than the smaller systems,
and unsaturated thiacrown ethers were oxidized more easily than corresponding saturated systems. The reaction
of 4 with silver trifluoroacetate in acetone afforded the colorless complex AgI(C2H2S)5(CF3COO) 9. The crystal
structure of 9 was determined by X-ray analysis, and it was found that three of the five sulfur atoms bonded
to the silver atom.
Introduction
Over the past 20 years, there have been tremendous advances
in the chemistry of sulfur-substituted crown ethers, thiacrown
ethers.1,2 Among the differences between crown ethers and
thiacrown ethers, the latter are known to coordinate to transition
metals1,3 whereas crown ethers prefer to coordinate with alkaline
and alkaline earth metals.4 On the other hand, unsaturated
thiacrown ethers with cis geometry across the carbon-carbon
double bonds are considered to be more conformationally
restricted than corresponding saturated systems. Therefore, high
selectivity toward metals is expected in the formation of metal
complexes with unsaturated thiacrown ethers. Among these
unsaturated systems, the smallest cyclic compound, 1,4-dithiin,
has been widely studied;5 however, the larger cyclic systems
have only rarely been investigated. Very recently, two un-
saturated thiacrown ethers, 9- and 18-membered cyclic com-
pounds, which are fused with benzene rings, were synthesized
by Nakayama and co-workers.6 However, little is known about
their chemical and physical properties. In this paper, we report
the synthesis, structures, redox properties, and formation with
silver complex of novel unsaturated thiacrown ethers without
substituents.
Results and Discussion
Synthesis. When cis-1,2-dichloroethylene was treated with
sodium sulfide in acetonitrile at 50 °C, 6-, 9-, 12-, 15-, 18-,
21-, 24-, and 27-membered unsaturated thiacrown ethers (1,4-
dithiin, 9-UT-3, 12-UT-4, 15-UT-5, 18-UT-6, 21-UT-7, 24-UT-
8, and 27-UT-9, respectively)7,8 1-8 were formed, although the
yields were low (18% total yield) (Table 1). Even attempts to
(1) (a) Crown Compounds: Toward Future Applications; Cooper, R. S.,
Ed.; VCH Publishers: New York, 1992; Chapter 14 and 15. (b) Cooper, S.
R. Acc. Chem. Res. 1988, 21, 141. (c) Blake, A. J.; Schro¨der, M. AdV.
Inorg. Chem. 1990, 35, 1. (d) Cooper, S. R.; Rawle, S. C. Struct. Bonding
1990, 72, 1.
(2) (a) Macrocycle Synthesis: A Practical Approach; Parker, D., Ed.
Oxford University Press: New York, 1996; Chapter 3. (b) Buter, J.; Kellogg,
R. M. Org. Synth. 1987, 65, 150. (c) Wolf, R. E., Jr.; Hartman, J. R.;
Ochrymowycz, L. A.; Cooper, S. R. Inorg. Synth. 1989, 25, 122. (d) Blower,
P. J.; Cooper, S. R. Inorg. Chem. 1987, 26, 2009.
(3) (a) Pedersen, C. J. J. Org. Chem. 1971, 36, 254. (b) Murray, S. G.;
Hartley, F. R. Chem. ReV. 1981, 81, 365.
(4) (a) Pedersen, C. J. J. Am. Chem. Soc. 1967, 89, 2495; 7017. (b)
Frensdorff, H. K. J. Am. Chem. Soc. 1971, 93, 600. (c) Poonia, N. S. J.
Am. Chem. Soc. 1974, 96, 1012. (d) Izatt, R. M.; Bradshaw, J. S.; Nielsen,
S. A.; Lamb, J. D.; Christensen, J. J. Chem. ReV. 1985, 85, 271. (e) Izatt,
R. M.; Pawlak, K.; Bradshaw, J. S. Chem. ReV. 1991, 91, 1721.
(5) (a) Russell, J. Org. Magn. Reson. 1972, 4, 433. (b) Meijer, J.;
Vermeer, P.; Verkruijsse, H. D.; Brandsma, L. Recl. TraV. Chim. Pays-Bas
1973, 92, 1326. (c) Long, R. C.; Goldstein, J. H. J. Mol. Spectrosc. 1971,
40, 632. (d) Butler, R. S.; Read, J. M.; Goldstein, J. H. J. Mol. Spectrosc.
1970, 35, 83. (e) Schroth, W.; Hassfeld, M. Z. Chem. 1970, 10, 296. (f)
Schroth, W.; Borsdorf, R.; Herzschuh, R.; Seidler, J. Z. Chem. 1970, 10,
147. (g) Deb, K. K.; Bloor, J. E.; Cole, T. C. Inorg. Chem. 1972, 10, 2428.
(h) Schoufs, M.; Mayer, J.; Vermeer, P.; Brandsma, L. Recl. TraV. Chim.
Pays-Bas 1977, 96, 259. (i) Bojkova, N. V.; Glass, R. S. Tetrahedron Lett.
1998, 39, 9125.
(6) Nakayama, J.; Kaneko, A.; Sugihara, Y.; Ishii, A. Tetrahedron 1999,
55, 10057.
(7) In this paper, unsaturated thiacrown ethers are abbreviated as x-UT-y
(UT, unsaturated thiacrown ether; x, x-membered ring; y, number of sulfur
atom).
10.1021/ja0102742 CCC: $20.00 © 2001 American Chemical Society
Published on Web 10/27/2001

Unsaturated Thiacrown Ethers
J. Am. Chem. Soc., Vol. 123, No. 47, 2001 11535
Figure 1. ORTEP drawings of (a) 15-UT-5 (4), (b) 18-UT-6 (5), (c) 21-UT-7 (6), (d) 24-UT-8 (7), and (e) 27-UT-9 (8) showing thermal ellipsoids
at 50% probability level. Shortest and longest distances between the center of the molecule and the sulfur atoms are denoted.
Table 1. Reaction of cis-1,2-Dichloroethylene with Sodium
Sulfide in Acetonitrile
react cis-1,2-dichloroethylene with sodium sulfide in the pres-
ence of Cs2CO3, a method useful for preparing saturated
thiacrown ethers,2,9 yields were hardly improved. The low yield
may be due to the heterogeneous reaction system; i.e., sodium
sulfide is less soluble in acetonitrile. In the presence of 0.1 equiv
of 15-crown-5 as a phase-transfer catalyst, the reaction pro-
ceeded smoothly even at room temperature, and the total yield
of unsaturated thiacrown ethers was improved to 32% (1/2/3/
4/5/6/7/8 ) 44/4/trace/6/19/14/8/5). The total yield was in-
creased to 40% when 0.4 equiv of 15-crown-5 was added to
the reaction system; however, no further improvement was
observed when 1.0 equiv of 15-crown-5 was added. Among
these, 1 and 4-8 could be isolated by silica gel column
chromatography (hexane/acetone ) 2/1). In this reaction, fluffy
yieldsa
15-crown-5 temp time total
run
(equiv)
(°C)
(h)
(%)
1/2/3/4/5/6/7/8
1
2
3
40
rt
rt
45
45
45
18
32
40
48/6/trace/8/14/10/8/6
44/4/trace/6/19/14/8/5
44/3/trace/4/18/16/10/5
0.1
0.4
1
a Yields were determined by H NMR spectra.
amorphous solids, which were not soluble in organic and
aqueous phase, were also obtained. The solids may be electro-
conducting poly(vinylene sulfides) reported by Ikeda and co-
workers.10
(10) (a) Ikeda, Y.; Ozaki, M.; Arakawa, T. J. Chem. Soc., Chem.
Commun. 1983, 1518. (b) Ikeda, Y.; Ozaki, M.; Arakawa, T. Polym.
Commun. 1984, 25, 79. (c) Ikeda, Y.; Nagoya, I.; Arakawa, T. Synth. Met.
1987, 21, 235.
(8) 9-UT-3 (2) and 12-UT-4 (3) were identified by 1H NMR, 13C NMR,
and GC/MS for the mixture of 2 and 3.
(9) Buter, J.; Kellog, R. M. J. Org. Chem. 1981, 46, 4481.

11536 J. Am. Chem. Soc., Vol. 123, No. 47, 2001
Table 2. Summary of X-ray Crystallographic Data
Tsuchiya et al.
15-UT-5 (4)
18-UT-6 (5)
21-UT-7 (6)
C14H14S7
24-UT-8 (7)
C16H16S8
27-UT-9 (8)
empirical formula
formula weight
crystal system
space group
a, Å
C10H10S5
290.49
C12H12S6
348.59
C18H18S9
522.88
406.68
464.78
monoclinic
P21/n (No. 14)
9.7111(7)
14.1165(6)
10.2523(6)
113.659(1)
1287.3(1)
4
monoclinic
P21/n (No. 14)
8.1989(4)
18.322(1)
11.0518(7)
107.835(1)
1580.4(1)
4
orthorhombic
Pbca (No. 61)
17.1915(6)
19.9131(6)
11.2108(4)
orthorhombic
Pbca (No. 61)
17.889(1)
21.852(1)
11.4800(7)
monoclinic
P21/n (No. 14)
12.5632(8)
15.824(1)
12.793(1)
100.001(2)
2504.6(3)
4
b, Å
c, Å
â, deg
V, Å3
3837.9(2)
8
4487.6(5)
8
Z
F(000)
600.00
1.499
23
720.00
1.465
23
1680.00
1.408
23
1920.00
1.376
23
1080.00
1.387
23
Dcalc, g/cm3
T, °C
crystal size, nm
µ (Mo KR), cm-1
2θmax, deg
no. of reflns measd
no. of reflns obsd
no. of variables
0.60 × 0.50 × 0.40
0.40 × 0.50 × 0.40
0.40 × 0.50 × 0.30
0.40 × 0.35 × 0.13
0.45 × 0.50 × 0.50
8.64
8.44
8.11
7.93
7.99
54.9
12361
2433[I > 3.00σ(I)]
136
0.078; 0.103
0.036
55.0
14792
2967[I > 3.00σ(I)]
163
0.136; 0.113
0.046
55.0
34982
1859[I > 3.00σ(I)]
190
0.081; 0.106
0.042
55.0
21025
3620[I > 0.00σ(I)]
217
0.103; 0.103
0.038
55.0
13448
1766[I > 3.00σ(I)]
244
0.106; 0.123
0.055
b
Ra; Rw
R1c
2
2
2
2
a R ) ∑(Fo - Fc2)/∑Fo . b Rw ) (∑ω(Fo - Fc2)2/∑ω(Fo ))1/2; ω ) 1/σ2(Fo). c R1 ) ∑||Fo| - |Fc||/∑|Fo|.
Table 3. Selected Bond Distances and Angles of 4-8
15-UT-5 (4)
S(1)-C(2)
S(1)-C(15)
S(4)-C(3)
S(4)-C(5)
S(7)-C(6)
S(7)-C(8)
S(10)-C(9)
S(10)-C(11)
S(13)-C(12)
S(13)-C(14)
18-UT-6 (5)
1.743(2) S(1)-C(2)
21-UT-7 (6)
24-UT-8 (7)
1.752(5) S(1)-C(2)
27-UT-9 (8)
Distances, Å
1.744(2) S(1)-C(2)
1.692(8) S(1)-C(2)
1.698(9)
1.76(1)
1.758(2) S(1)-C(18)
1.755(2) S(4)-C(3)
1.761(3) S(4)-C(5)
1.741(2) S(7)-C(6)
1.743(2) S(7)-C(8)
1.753(3) S(10)-C(9)
1.749(2) S(10)-C(11)
1.749(2) S(13)-C(12)
1.746(3) S(13)-C(14)
S(16)-C(15)
1.743(2) S(1)-C(21)
1.762(3) S(4)-C(3)
1.749(3) S(4)-C(5)
1.736(3) S(7)-C(6)
1.741(3) S(7)-C(8)
1.743(2) S(10)-C(9)
1.725(3) S(10)-C(11)
1.759(3) S(13)-C(12)
1.757(3) S(13)-C(14)
1.740(2) S(16)-C(15)
1.755(2) S(16)-C(17)
S(19)-C(18)
1.739(5) S(1)-C(24)
1.742(5) S(4)-C(3)
1.743(5) S(4)-C(5)
1.732(6) S(7)-C(6)
1.738(6) S(7)-C(8)
1.738(5) S(10)-C(9)
1.730(6) S(10)-C(11)
1.722(6) S(13)-C(12)
1.741(5) S(13)-C(14)
1.757(5) S(16)-C(15)
1.725(5) S(16)-C(17)
1.740(5) S(19)-C(18)
1.725(5) S(19)-C(20)
S(22)-C(21)
1.725(8) S(1)-C(27)
1.750(7) S(4)-C(3)
1.707(8) S(4)-C(5)
1.749(8) S(7)-C(6)
1.690(8) S(7)-C(8)
1.722(8) S(10)-C(9)
1.723(8) S(10)-C(11)
1.717(7) S(13)-C(12)
1.737(8) S(13)-C(14)
1.721(8) S(16)-C(15)
1.713(8) S(16)-C(17)
1.706(8) S(19)-C(18)
1.682(8) S(19)-C(20)
1.690(8) S(22)-C(21)
1.718(8) S(22)-C(23)
S(25)-C(24)
1.730(10)
1.725(9)
1.729(9)
1.739(9)
1.700(9)
1.733(8)
1.729(8)
1.730(8)
1.740(8)
1.732(8)
1.724(9)
1.709(10)
1.759(9)
1.72(1)
S(16)-C(17)
S(19)-C(20)
S(22)-C(23)
1.722(9)
1.69(1)
S(25)-C(26)
Angles, deg
C(15)-S(1)-C(2)
C(3)-S(4)-C(5)
C(6)-S(7)-C(8)
100.1(1) C(18)-S(1)-C(2)
101.2(1) C(3)-S(4)-C(5)
101.2(1) C(6)-S(7)-C(8)
101.5(1) C(21)-S(1)-C(2)
100.7(1) C(3)-S(4)-C(5)
102.8(1) C(6)-S(7)-C(8)
101.7(2) C(24)-S(1)-C(2)
103.0(3) C(3)-S(4)-C(5)
103.1(3) C(6)-S(7)-C(8)
105.5(4) C(27)-S(1)-C(2)
100.8(4) C(3)-S(4)-C(5)
103.6(4) C(6)-S(7)-C(8)
104.0(5)
103.8(5)
102.8(5)
C(9)-S(10)-C(11) 102.8(1) C(9)-S(10)-C(11) 102.1(1) C(9)-S(10)-C(11) 103.5(3) C(9)-S(10)-C(11) 104.2(4) C(9)-S(10)-C(11) 103.2(4)
C(12)-S(13)-C(14) 107.6(1) C(12)-S(13)-C(14) 100.3(2) C(12)-S(13)-C(14) 100.7(3) C(12)-S(13)-C(14) 100.5(4) C(12)-S(13)-C(14) 103.9(4)
C(15)-S(16)-C(17) 101.0(1) C(15)-S(16)-C(17) 102.5(3) C(15)-S(16)-C(17) 102.8(4) C(15)-S(16)-C(17) 101.2(4)
C(18)-S(19)-C(20) 103.4(3) C(18)-S(19)-C(20) 103.4(4) C(18)-S(19)-C(20) 101.7(5)
C(21)-S(22)-C(23) 106.5(4) C(21)-S(22)-C(23) 103.4(5)
C(24)-S(25)-C(26) 101.2(5)
1
The H and 13C NMR signals of the unsaturated thiacrown
ethers exhibited lower field shifts with an increase in the ring
size from 1 to 4 in CDCl3 (1H NMR (ppm): 1, 6.21; 2, 6.27; 3,
6.43; 4, 6.48. 13C NMR (ppm): 1, 121.2; 2, 123.8; 3, 126.1; 4,
126.9) and upper field shifts with an increase in the ring size
from 4 to 8 in CDCl3 (1H NMR (ppm): 5, 6.40; 6, 6.33; 7,
6.30; 8, 6.28. 13C NMR (ppm): 5, 125.3; 6, 123.6; 7, 122.4; 8,
121.5). These results suggest that the electron density of the
olefin moieties increases with increasing ring size from 4 to 8
and decreasing ring size from 4 to 1.
synthesized in this study are a fixed cis form; therefore, it is
interesting to observe the conformational change from saturated
thiacrown ethers, whose carbon-carbon single bonds can rotate
freely, to unsaturated thiacrown ethers. The crystal structures
of 15-, 18-, 21-, 24-, and 27-membered unsaturated thiacrown
ethers 4-8 were determined by X-ray crystallographic analysis
(Figure 1). The crystallographic data, selected bond angles, and
bond lengths for these X-ray structures are summarized in Tables
2 and 3. All of the ORTEP drawings show that there are cavities
in these molecules, and the sulfur atoms are nearly coplanar. In
Crystal Structures. Earlier structural work on saturated
thiacrown ethers revealed that sulfur-sulfur 1,4-interactions
disfavor gauche placement at S-C-C-S bonds.11,12,13 In these
cases, electron-electron repulsion between sulfur atoms de-
stabilizes gauche placement. The unsaturated thiacrown ethers
(11) (a) Wolfe, S. Acc. Chem. Res. 1972, 5, 102. (b) Zefirov, N. S.
Tetrahedron 1977, 33, 3193. (c) Juaristi, E. J. Chem. Educ. 1979, 56, 438.
(12) Wolf, R. E., Jr.; Hartman, J. R.; Storey, J. M. E.; Foxman, B. M.;
Cooper, S. R. J. Am. Chem. Soc. 1987, 109, 4328.
(13) Hartman, J. R.; Wolf, R. E., Jr.; Foxman, B. M.; Cooper, S. R. J.
Am. Chem. Soc. 1983, 105, 131.

Unsaturated Thiacrown Ethers
J. Am. Chem. Soc., Vol. 123, No. 47, 2001 11537
Figure 2. UV spectra of 15-UT-5 (4), 18-UT-6 (5), 21-UT-7 (6), 24-
UT-8 (7), and 27-UT-9 (8) in acetonitrile.
Table 4. Spectral Data of 4-8 in Acetonitrile, Ethanol, and
Cyclohexane
λ
max, nm (ꢀ, M-1cm-1
)
compd
acetonitrile
ethanol
cyclohexane
4
5
6
7
8
255 (24 000)
261 (33 000)
266 (40 000)
271 (50 000)
276 (67 000)
260 (22 000)
267 (27 000)
268 (32 000)
274 (49 000)
277 (51 000)
267 (16 000)
271 (22 000)
274a
277a
283a
a Molar absorption coefficient has not been determined due to
insolubility, and the spectra were measured in saturated solutions.
the crystal structure of 5, all of the sulfur atoms are oriented
toward the inside of the ring (endodentate) whereas the
corresponding thiacrown ether, 1,4,7,10,13,16-hexathiacyclo-
octadecane (18S6), has four endodentate and two exodentate
sulfur atoms in the crystalline state.12,13 In the crystal structures
of 6-8, all sulfur atoms are endodentate. The C-S bond lengths
in 4 (1.74-1.76 Å) and 5 (1.74-1.76 Å) are shorter than those
in 15S5 (1.80-1.95 Å)12 and 18S6 (1.80-1.96 Å).12,13 The bond
angles in the crystal structures of 4-8 are almost strain-free
(4: S-C-C, 121.7-132.4°; C-S-C, 100.1-107.6°. 5: S-C-
C, 120.8-124.3°; C-S-C, 100.3-102.8°. 6: S-C-C, 120.7-
123.5°; C-S-C, 100.7-103.5°. 7: S-C-C, 120.3-124.5°;
C-S-C, 100.5-106.5°. 8: S-C-C, 120.4-125.0°; C-S-C,
101.2-104.0°). The most interesting point of these structures
is the size of the cavity. The distances between the center of
the molecule and the sulfur atoms in 4 and 5 are 1.94-3.57
(average, 2.73) and 2.37-4.07 (average, 3.01) Å, respectively,
which are shorter than those in saturated systems [15S5, 3.44-
3.99 (average, 3.58)12 Å; 18S6, 2.36-4.55 (average, 3.56)12,13
Å]. Those distances in 6-8 are 3.37-3.80 (average, 3.59),
3.97-4.24 (average, 4.06), and 4.11-4.90 (average, 4.53) Å,
respectively. From those distances and van der Waals radii of
sulfur atoms, the cavity sizes in 4-8 were estimated to be 1.76,
2.34, 3.48, 4.43, and 5.36 Å, respectively, at the inside of the
sulfur atoms.
UV Spectra of 4-8. The UV spectrum of 4 shows an
absorption maximum at 255 nm (ꢀ 2.4 × 104) in acetonitrile,
as shown in Figure 2. With an increase in the ring size, the
absorption maximums shift to a longer wavelength and the
extinction coefficients increase; the UV spectra of larger
unsaturated thiacrown ethers 5-8 show absorption maximums
at 261 (ꢀ 3.3 × 104), 266 (ꢀ 4.0 × 104), 271 (ꢀ 5.0 × 104), and
276 (ꢀ 6.7 × 104) nm, respectively. This tendency of the shifts
of absorption maximums can be explained in terms of delocal-
ization; the excited state would be more stabilized by delocal-
ization of the unpaired electron in the larger systems. The UV
spectra of 4 in ethanol and cyclohexane show absorption
Figure 3. ORTEP drawing of AgI(15-UT-5)(CF3COO) (9) showing
thermal ellipsoids at 50% probability level. Selected bond lengths (Å)
and angles (deg): Ag-O(1), 2.280(3); Ag-S(1), 2.747(1); Ag-S(3),
2.633(1); Ag-S(5), 2.685(1); S(1)-Ag-S(3), 100.50(3); S(1)-Ag-
S(5), 75.41 (3); S(3)-Ag-S(5), 112.66(3); S(1)-Ag-O(1), 101.82(8);
S(3)-Ag-O(1), 123.78(7); S(5)-Ag-O(1), 122.69(7).
maximums at 260 (ꢀ 2.2 × 104) and 267 (ꢀ 1.6 × 104) nm,
respectively, as shown in Table 4. The absorption maximums
of 5-8 also shift to longer wavelengths in nonpolar solvent,
and the extinction coefficients decrease with a decrease in the
polarity of the solvent. Thus, the absorptions can be assigned
to n f π* transitions.
Electrochemistry of 4-8. The electrochemical oxidation of
unsaturated thiacrown ethers was examined. A cyclic voltammo-
gram of 4 was measured in acetonitrile at a platinum working
electrode and showed an irreversible oxidation peak at +0.79
V versus Fc/Fc+ with a scanning potential range of +2.0 to
-2.0 V. The reduction peak was not observed in this scanning
potential range. The cyclic voltammograms of 5-8 also showed
irreversible oxidation peaks at +0.77, +0.75, +0.60, and +0.55
V, respectively. These results indicate that the larger unsaturated
thiacrown ethers would be oxidized more easily than the smaller
systems, probably due to the effect of delocalization of the
resulting cation. A cyclic voltammogram of 18S6 was measured
to compare the oxidation potential. An irreversible oxidation
peak was observed at +1.05 V. It was found that unsaturated
thiacrown ethers are oxidized easily than saturated systems.
Silver Complex with 15-UT-5 (4). The reaction of 4 with
silver trifluoroacetate in acetone gave the colorless complex
AgI(15-UT-5)(CF3COO) (9) in 95% yield. The crystal structure
of 9 was determined by X-ray analysis (Figure 3). AgI has a
distorted tetrahedral geometry and is coordinated by three sulfur
atoms of the macrocycle and a trifluoroacetate anion. The bond
angles S(1)-Ag-S(5), S(1)-Ag-S(3), and S(3)-Ag-S(5) are
75.4, 100.5, and 112.7°, respectively. The silver-sulfur bond
distances range from 2.63 to 2.75 Å, and the Ag‚‚‚S(2) and

11538 J. Am. Chem. Soc., Vol. 123, No. 47, 2001
Tsuchiya et al.
× 104) nm. Anal. Calcd for C12H12S6: C, 41.34; H, 3.47. Found: C,
41.34; H, 3.48.
Ag‚‚‚S(4) distances are 3.36 and 2.87 Å, respectively. The
distorted geometry may be due to Ag‚‚‚S(4) interaction, since
the S(4) atom is close to the AgI center. Cyclic voltammetry of
9 in acetonitrile at a platinum working electrode shows
irreversible oxidation and reduction peaks at +0.80 and -0.27
V versus Fc/Fc+, respectively, with a scanning potential range
of +2.0 to -2.0 V. The results indicate that the oxidized and
(Z,Z,Z,Z,Z,Z,Z)-1,4,7,10,13,16,19-Heptathiacycloheneicosa-
2,5,8,11,14,17,20-heptaene (21-UT-7) (6): mp 195-196 °C (colorless
1
prisms from acetone); H NMR (500 MHz, CDCl3) δ 6.33 (14H, s);
13C NMR (125 MHz, CDCl3) δ 123.6; MS (EI) m/z 406 (M+, 7%),
116 (C4H4S2+, 100%); IR (KBr) νmax 3026, 1556, 1277, 810, 716, 673,
657, 636, 535, 400 cm-1; UV (CH3CN) λmax 266 (ꢀ 4.0 × 104) nm,
(EtOH) λmax 268 (ꢀ 3.2 × 104) nm, (cyclohexane) λmax 274 nm. Anal.
Calcd for C14H14S7: C, 41.34; H, 3.47. Found: C, 41.32; H, 3.39.
(Z,Z,Z,Z,Z,Z,Z,Z)-1,4,7,10,13,16,19,22-Octathiacyclotetracosa-
2,5,8,11,14,17,20,23-octaene (24-UT-8) (7): mp 190-192 °C (color-
1
reduced products are unstable in acetonitrile. In the H NMR
spectra, five olefins of the ligand were observed equivalently
in acetone-d6, even at 180 K (300 K, 6.88 ppm; 180 K, 7.09
ppm), and the results show that there is facile interconversion
between the coordinated sulfur atoms and noncoordinated sulfur
atoms in the solution.
1
less prisms from acetone, dec); H NMR (500 MHz, CDCl3) δ 6.30
(16H, s); 13C NMR (125 MHz, CDCl3) δ 122.4; MS (EI) m/z 464 (M+,
3%), 116 (C4H4S2+, 100%); IR (KBr) νmax 3026, 1558, 1272, 808, 725,
657, 625, 539, 410 cm-1; UV (CH3CN) λmax 271 (ꢀ 5.0 × 104) nm,
(EtOH) λmax 274 (ꢀ 4.9 × 104) nm, (cyclohexane) λmax 277 nm. Anal.
Calcd for C16H16S8: C, 41.34; H, 3.47. Found: C, 41.40; H, 3.48.
(Z,Z,Z,Z,Z,Z,Z,Z,Z)-1,4,7,10,13,16,19,22,25-Nonathiacyclohepta-
cosa-2,5,8,11,14,17,20,23,26-nonaene (27-UT-9) (8): mp 202-203
°C (colorless prisms from acetone, dec); 1H NMR (500 MHz, CDCl3)
δ 6.28 (18H, s); 13C NMR (125 MHz, CDCl3) δ 121.5; MS (EI) m/z
522 (M+, 3%), 116 (C4H4S2+, 100%); IR (KBr) νmax 3034, 1604, 1562,
1272, 871, 807, 720, 656, 624, 542 cm-1; UV (CH3CN) λmax 276 (ꢀ
6.7 × 104) nm, (EtOH) λmax 277 (ꢀ 5.1 × 104) nm, (cyclohexane) λmax
283 nm. Anal. Calcd for C18H18S9: C, 41.34; H, 3.47. Found: C, 41.29;
H, 3.45.
Conclusions
Novel unsaturated thiacrown ethers (1-8) were synthesized
by reaction of cis-1,2-dichloroethylene with sodium sulfide. The
structures of 4-8 were determined by X-ray crystallographic
analysis. The UV spectra and the cyclic voltammograms of the
unsaturated thiacrown ethers (4-8) show that the excited states
and electrochemically oxidized species of lager unsaturated
thiacrown ethers are liable to be stabilized by delocalization
more easily than smaller unsaturated ones. Comparing the
oxidation potential of unsaturated thiacrown ether with corre-
sponding saturated thiacrown ether, it was found that unsaturated
thiacrown ethers were oxidized more easily than saturated
systems. The formation of a silver complex with 4 was examined
in which three of the five sulfur atoms bonded to the silver
atom in the crystalline state.
Synthesis of Silver Complex with 15-UT-5. A solution of silver
trifluoroacetate (58 mg, 0.26 mmol) in acetone (3 mL) was added to a
solution of 15-UT-5 (4) (70 mg, 0.24 mmol) in acetone (15 mL) under
nitrogen. The reaction mixture was stirred at room temperature for 3
h. Crystallization by slow evaporation of acetone yielded colorless
crystals of AgI(15-UT-5)(CF3COO) (9) (117 mg, 95%).
AgI(15-UT-5)(CF3COO) (9): mp 176-177 °C (colorless prisms
Experimental Section
1
from acetone, dec); H NMR (500 MHz, acetone-d6) δ 6.90 (10H, s);
13C NMR (125 MHz, CDCl3) δ 119.0 (q, J ) 293 Hz, CF3CO), 127.5
General Information. Acetonitrile and cyclohexane were distilled
from CaH2, and acetone was distilled from CaSO4 prior to use.
Commercially available 95% ethanol was used without further purifica-
tion. Column chromatography was performed with Merk 7734 Kieselgel
60. Melting points were determined on a Yamato MP-21 melting point
apparatus. UV-visible spectra were measured on a Hitachi U-3500
spectrometer. IR spectra were measured on a Perkin-Elmer Spectrum
+
(HCdCH), 161.7 (q, J ) 33 Hz, CF3CO); MS (EI) m/z 290 (C10H10S5
,
3%), 116 (C4H4S2+, 100%); IR (KBr) νmax 3026, 3010, 2999, 1682,
1556, 1525, 1432, 1315, 1293, 1283, 1208, 1032, 854, 839, 810, 707,
680, 659, 649, 448 cm-1. Anal. Calcd for C12H10F3O2S5Ag: C, 28.18;
H, 1.97. Found: C, 28.18; H, 1.94.
Cyclic Voltammetry. Cyclic voltammograms were measured in
acetonitrile. A 0.1 M solution of tetra-n-butylammonium perchlorate
was used as supporting electrolyte solution. The solid samples were
added and dissolved to this solution to yield 1.5 mM concentrations of
the respective materials. Cyclic voltammograms were recorded at scan
rate of 100 mV s-1. Formal oxidation potentials are given versus the
reference system ferrocene/ferrocenium (Fc/Fc+) in volts.
X-ray Structure Determination. Data of X-ray diffraction were
collected by Rigaku RAXIS-RAPID imaging plate two-dimensional
area detector using graphite-monochromated Mo KR radiation (λ )
0.710 70 Å) to 2θmax of 55.0°. All of the crystallographic calculations
were performed by using teXan software package of the Molecular
Structure Corp. The crystal structure was solved by the direct methods
and refined by the full-matrix least squares. All non-hydrogen atoms
were refined anisotropically. The summary of the fundamental crystal
data and experimental parameters for structure determinations is given
in Table 2. The experimental details including data collection, data
reduction, and structure solution and refinement as well as the atomic
coordinates and Biso/Beq, anisotropic displacement parameters have been
deposited in the Supporting Information.
1
GX. H and 13C spectra were recorded on a JEOL JNM-EX-500 FT
NMR system. Mass spectra (MS) were determined on a JEOL
GCMATE.
Synthesis of Unsaturated Thiacrown Ethers. Ground Na2S‚9H2O
(6.64 g, 27.6 mmol) and 15-crown-5 (2.43 g, 11.0 mmol) was suspended
in 230 mL of acetonitrile. A solution of cis-1,2-dichloroethylene (4.50
g, 46.4 mmol) in acetonitrile (40 mL) was added dropwise to the
suspension with stirring for 1 h. After additional stirring for 45 h, the
reaction mixture was filtered, and the filtrate was concentrated in vacuo.
The residue was extracted with AcOEt, washed with H2O, and dried
over MgSO4. The products were isolated by silica gel column
chromatography (hexane/acetone ) 2/1; Rf: 1,5a,b 0.80; 4, 0.52; 5, 0.30;
6, 0.18; 7, 0.07; 8, 0.04).
(Z,Z,Z,Z,Z)-1,4,7,10,13-Pentathiacyclopentadeca-2,5,8,11,14-pen-
taene (15-UT-5) (4): mp 128-129 °C (colorless prisms from di-
chloromethane); 1H NMR (500 MHz, CDCl3) δ 6.48 (10H, s); 13C NMR
(125 MHz, CDCl3) δ 126.9; MS (EI) m/z 290 (M+, 17%), 116 (C4H4S2+
,
100%); IR (KBr) νmax 3025, 3009, 2998, 1555, 1525, 1314, 1293, 1283,
854, 810, 706, 680, 659, 448, 411 cm-1; UV (CH3CN) λmax 255 (ꢀ 2.4
× 104) nm, (EtOH) λmax 260 (ꢀ 2.2 × 104) nm, (cyclohexane) λmax 267
(ꢀ 1.6 × 104) nm. Anal. Calcd for C10H10S5: C, 41.34; H, 3.47.
Found: C, 41.16; H, 3.35.
Acknowledgment. This work was financially supported in
part by a Grant-in-Aid for Scientific Research from the Ministry
of Education, Science, Sports, and Culture, Japan.
(Z,Z,Z,Z,Z,Z)-1,4,7,10,13,16-Hexathiacyclooctadeca-2,5,8,11,14,
17-hexaene (18-UT-6) (5): mp 165-166 °C (colorless prisms from
Supporting Information Available: X-ray crystallographic
files (CIF) for 4-9. This material is available free of charge
via the Internet at http://pubs.acs.org. See any current masthead
page for ordering information and Web access instructions.
1
dichloromethane); H NMR (500 MHz, CDCl3) δ 6.40 (12H, s); 13C
NMR (125 MHz, CDCl3) δ 125.3; MS (EI) m/z 348 (M+, 8%), 116
(C4H4S2+, 100%); IR (KBr) νmax 3015, 1547, 1525, 1282, 811, 721,
666, 641, 540, 450, 365 cm-1; UV (CH3CN) λmax 261 (ꢀ 3.3 × 104)
nm, (EtOH) λmax 267 (ꢀ 2.7 × 104) nm, (cyclohexane) λmax 271 (ꢀ 2.2
JA0102742