Molecular saddles. 7. New 9,10-Bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene cyclophanes: Synthesis, redox properties, and x-ray crystal structures of neutral species and a dication salt

Article abstract of DOI:10.1021/jo001524k

We report the synthesis of cyclophanes 18-20 by ester-forming macrocyclization reactions of diols 15 and 16 with 1,4-benzenedicarbonyl chloride. Compounds 18 and 19 display a two-electron, quasireversible oxidation wave in the cyclic voltammogram to yield the dication species at E^ox_pa 0.52 and 0.47 V, respectively (vs Ag/AgCl in acetonitrile), whereas the 2 + 2 product 20 undergoes a single four-electron oxidation process at E^ox_pa 0.51 V. X-ray crystal structures are reported for compounds 18-20 and the dication salt 18²⁺(I₃^-)₂· (I₂)_0.5. For comparative purposes, the structures are also reported for the precursor diol 15 and its dication salt 15²⁺(ClO₄^-)₂, which was obtained by electrocrystallization. In the neutral cyclophanes 18-20, the 9,10-bis(1,3-dithiol-2-ylidene)-9, 10-dihydroanthracene moieties adopt a saddle-shaped conformation. The overall measure of folding, the dihedral angle (θ) between the S(1)C(16)C(17)S(2) and S(5)C(21)C(22)S(6) planes, is similar in 15 and 18 (87.6° and 83.7°, respectively) whereas this angle is significantly narrower in 19 (61.1°), illustrating the flexibility of the saddle conformation and its dependence on the packing. Dimeric molecule 20 contains two saddle moieties with very similar conformations, θ = 73.4° and 73.1°. The structures of dication salts 15²⁺(ClO₄^-)₂ and 18²⁺(I₃^-)₂· (I₂)_0.5 reveal that a dramatic conformational change accompanies oxidation of the donor with the dithiolium rings planar and nearly perpendicular to the mean plane of the anthracene moieties. A notable feature of 18²⁺ is that the bridge enforces a fold of 22° along the C(9)...C(10) vector of the anthracene unit. In 15²⁺ there is no fold about this axis, instead the anthracene moiety is slightly twisted with the two (planar) outer rings forming an angle of 7°.

Full text of DOI:10.1021/jo001524k

J . Org. Chem. 2001, 66, 3313-3320
3313
Molecu la r Sa d d les. 7.1 New
9,10-Bis(1,3-d ith iol-2-ylid en e)-9,10-d ih yd r oa n th r a cen e
Cyclop h a n es: Syn th esis, Red ox P r op er ties, a n d X-r a y Cr ysta l
Str u ctu r es of Neu tr a l Sp ecies a n d a Dica tion Sa lt
Christian A. Christensen, Andrei S. Batsanov, Martin R. Bryce,* and J udith A. K. Howard
Department of Chemistry, University of Durham, Durham DH1 3LE, UK
m.r.bryce@durham.ac.uk
Received October 26, 2000 (Revised Manuscript Received February 16, 2001)
We report the synthesis of cyclophanes 18-20 by ester-forming macrocyclization reactions of diols
15 and 16 with 1,4-benzenedicarbonyl chloride. Compounds 18 and 19 display a two-electron,
quasireversible oxidation wave in the cyclic voltammogram to yield the dication species at Eox
pa
0.52 and 0.47 V, respectively (vs Ag/AgCl in acetonitrile), whereas the 2 + 2 product 20 undergoes
a single four-electron oxidation process at Eox 0.51 V. X-ray crystal structures are reported for
pa
compounds 18-20 and the dication salt 182+(I3-)2‚(I2)0.5. For comparative purposes, the structures
are also reported for the precursor diol 15 and its dication salt 152+(ClO4-)2, which was obtained
by electrocrystallization. In the neutral cyclophanes 18-20, the 9,10-bis(1,3-dithiol-2-ylidene)-9,
10-dihydroanthracene moieties adopt a saddle-shaped conformation. The overall measure of folding,
the dihedral angle (θ) between the S(1)C(16)C(17)S(2) and S(5)C(21)C(22)S(6) planes, is similar in
15 and 18 (87.6° and 83.7°, respectively) whereas this angle is significantly narrower in 19 (61.1°),
illustrating the flexibility of the saddle conformation and its dependence on the packing. Dimeric
molecule 20 contains two saddle moieties with very similar conformations, θ ) 73.4° and 73.1°.
The structures of dication salts 152+(ClO4-)2 and 182+(I3-)2‚(I2)0.5 reveal that a dramatic conforma-
tional change accompanies oxidation of the donor with the dithiolium rings planar and nearly
perpendicular to the mean plane of the anthracene moieties. A notable feature of 182+ is that the
bridge enforces a fold of 22° along the C(9)...C(10) vector of the anthracene unit. In 152+ there is no
fold about this axis, instead the anthracene moiety is slightly twisted with the two (planar) outer
rings forming an angle of 7°.
Ch a r t 1
In tr od u ction
It is known that the central p-quinodimethane ring of
9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene
adopts a boat conformation due to steric interactions
between the peri-hydrogens and the sulfur atoms, and
thereby the molecule adopts a saddle shape.2 The bis-
(1,3-dithiole) substituents impart strong π-electron donor
properties to the system,3 e.g., compound 12b (Chart 1)
undergoes a single, two-electron, quasireversible redox
wave to yield a thermodynamically stable dication at Eox
ca. +0.45 V (vs Ag/AgCl in MeCN) in the cyclic voltam-
mogram (CV). At this redox stage there is gain of
aromaticity in the central anthracene unit and in the 6
π-electron dithiolium cations. A major conformational
change accompanies the oxidation process: X-ray crystal-
(1) Part 6: J ones, A. E.; Christensen, C. A.; Perepichka, D. F.;
Batsanov, A. S.; Beeby, A.; Low, P. J .; Bryce, M. R.; Parker, A. W.
Chem. Eur. J . 2001, 7, 973.
(2) (a) Bryce, M. R.; Moore, A. J .; Hasan, M.; Ashwell, G. J .; Fraser,
A. T.; Clegg, W.; Hursthouse, M. B.; Karaulov, A. I. Angew. Chem.,
Int. Ed. Engl. 1990, 29, 1450. (b) Batsanov, A. S.; Bryce, M. R.; Coffin,
M. A.; Green, A.; Hester, R. E.; Howard, J . A. K.; Lednev, I. K.; Martı´n,
N.; Moore, A. J .; Moore, J . N.; Ort´ı, E.; Sa´nchez, L.; Sav´ıron, M.;
Viruela, P. M.; Viruela, R.; Ye, T.-Q. Chem. Eur. J . 1998, 4, 2580. (c)
Bryce, M. R.; Finn, T.; Moore, A. J .; Batsanov, A. S.; Howard, J . A. K.
Eur. J . Org. Chem. 2000, 51.
(3) (a) Bryce, M. R.; Coffin, M. A.; Hursthouse, M. B.; Karaulov, A.
I.; Mu¨llen, K.; Scheich, H. Tetrahedron Lett. 1991, 32, 6029. (b) Moore,
A. J .; Bryce, M. R. J . Chem. Soc., Perkin Trans. 1 1991, 157. (c) Liu,
S.-G.; Pe´rez, I.; Mart´ın, N.; Echegoyen, L. J . Org. Chem. 2000, 65, 9092.
lography has established that 9,10-bis(1,3-dithiol-2-
ylidene)-9,10-dihydroanthracene dications have a planar
anthracene system with the 1,3-dithiolium cations almost
orthogonal to this plane.2a,4 Theoretical calculations
support the electrochemical and crystallographic data.5
10.1021/jo001524k CCC: $20.00 © 2001 American Chemical Society
Published on Web 04/14/2001

3314 J . Org. Chem., Vol. 66, No. 10, 2001
Christensen et al.
Sch em e 1
Derivatives of this extended π-donor system are currently
being studied as components of inter-4b,6 and intra-
molecular7 charge-transfer systems.
Cyclophanes are well-known building blocks in the
fields of macrocyclic and supramolecular chemistry8 with
redox-active systems,9,10 notably tetrathiafulvalene
derivatives,9 attracting current attention. We have re-
cently synthesized the first cyclophane structures 2 and
3 (Chart 1) which incorporate the 9,10-bis(1,3-dithiol-2-
ylidene)-9,10-dihydroanthracene framework.11 The oxida-
tion potentials of 2a ,11a 2b,11a and 3a 11b were raised
significantly to Eox ) ca. 0.70 V compared with those
pa
of nonbridged analogues, whereas for 3b Eox ) 0.47 V
pa
(vs Ag/AgCl in MeCN). The raised oxidation potentials
for 2a , 2b, and 3a reflect the reduced stability of the
twisted dication structure within the steric constraints
of the smaller cyclophanes.
Sch em e 2
Resu lts a n d Discu ssion
We now describe new 9,10-bis(1,3-dithiol-2-ylidene)-
9,10-dihydroanthracene cyclophanes 18-20 which are
formed by bridging across the 2,6-positions of the anthra-
cene unit, as opposed to bridging across the dithiole rings,
as was the case in the previous examples 2 and 3.11 This
new position of bridging has the attraction that, unlike
2 and 3, mixtures of geometric isomers cannot be formed
in the cyclization reactions. The aim of this work is to
probe further the effects of steric constraints on the redox
and structural properties of the system in both the
neutral and dication forms. The synthetic methodology
involves ester-forming macrocyclization reactions of the
precursor diol derivatives 15 and 16. Redox properties
and X-ray crystal structures of the cyclophanes are
reported, along with structures of the dication salts
152+(ClO4-)2 and 182+(I3-)2‚(I2)0.5
.
Syn th esis. We identified 2,6-dihydroxyanthraquinone
9 as an appropriate readily available starting material
for the synthesis of our target cyclophanes. For attach-
ment of oxyethylene chains to the hydroxy groups of 9,
we prepared reagents 6 and 8 in high yields using
standard procedures as shown in Scheme 1. Reactions
of 9 with 6 and 8, in the presence of potassium carbonate,
cleanly afforded compounds 10 and 11, which then
underwent 2-fold Horner-Wadsworth-Emmons olefina-
tion upon reaction with the anion generated by treatment
of phosphonate ester reagent 1212 with lithium diiso-
(4) (a) Triki, S. Ouahab, L.; Lorcy, D.; Robert, A. Acta Crystallogr.
1993, C49, 1189. (b) Bryce, M. R.; Finn, T.; Batsanov, A. S.; Kataky,
R.; Howard, J . A. K.; Lyubchik, S. B. Eur. J . Org. Chem. 2000, 1199.
(5) Mart´ın, N.; Sa´nchez, L.; Seoane, C.; Ort´ı, E.; Viruela, P. M.;
Viruela, R. J . Org. Chem. 1998, 63, 1268.
(6) Gautier, N.; Mercier, N.; Riou, A.; Gorgues, A.; Hudhomme, P.
Tetrahedron Lett. 1999, 40, 5997.
(7) (a) Herranz, M. A.; Mart´ın, N. Org. Lett. 1999, 1, 2005. (b)
Christensen, C. A.; Bryce, M. R.; Batsanov, A. S.; Howard, J . A. K.;
J eppersen, J . O.; Becher, J . Chem. Commun. 2000, 113.
(8) Vo¨gtle, F. Cyclophane Chemistry; Wiley: Chichester, 1993.
(9) (a) Otsubo, T.; Aso, Y.; Takimiya, K. Adv. Mater. 1996, 8, 203.
(b) Batsanov, A. S.; J ohn, D. E.; Bryce, M. R.; Howard, J . A. K. Adv.
Mater. 1998, 10, 1360. (c) Akutagawa, T.; Abe, Y.; Hasegawa, T.;
Nakamura, T.; Inabe, T.; Sugiura, K.; Sakata, Y.; Christensen, C. A.;
Lau, J .; Becher, J . J . Mater. Chem. 1999, 9, 2737. (d) Nielsen, M. B.;
Lomholt, C.; Becher, J . Chem. Soc. Rev. 2000, 29, 153. (e) Bryce, M.
R. J . Mater. Chem. 2000, 10, 589.
(10) Hascot, P.; Lorcy, D.; Robert, A.; Boubekeur, K.; Batail, P,
Carlier, R.; Tallec, A. J . Chem. Soc., Chem. Commun. 1995, 1229.
(11) (a) Finn, T.; Bryce, M. R.; Batsanov, A. S.; Howard, J . A. K.
Chem. Commun. 1999, 1835. (b) Godbert, N.; Batsanov, A. S.; Bryce,
M. R.; Howard, J . A. K. J . Org. Chem. 2001, 66, 713.
proylamide (LDA) at -78 °C, to yield the 9,10-bis(1,3-
dithiol-2-ylidene)-9,10-dihydroanthracene derivatives 13
and 14 in 69 and 81% yields, respectively (Scheme 2).
Removal of the silyl protecting groups with tetrabutyl-
ammonium fluoride readily afforded diol derivatives 15
(12) Moore, A. J .; Bryce, M. R. Tetrahedron Lett. 1992, 33, 1373.

Molecular Saddles. 7
J . Org. Chem., Vol. 66, No. 10, 2001 3315
Ta ble 1. Cyclic Volta m m etr ic Da ta a
Ch a r t 2
compd
Eoxpa/V
Eoxpc/V
∆E/Vb
13
14
15
16
18
19
20
0.47 (2e)
0.46 (2e)
0.47 (2e)
0.46 (2e)
0.52 (2e)
0.47 (2e)
0.51 (4e)
0.34
0.37
0.29
0.36
0.41
0.33
0.37
0.13
0.09
0.18
0.10
0.11
0.14
0.14
a
-
Compound ca. 2 × 10-3 M, vs Ag/AgCl, electrolyte Bu4N+PF6
,
acetonitrile, 20 °C, scan rate 100 mV s-1. Data obtained on a BAS
CV50W voltammetric analyzer with iR compensation. b ∆E ) Eox
pa
- Eox (Eox is the oxidation peak potential on the first anodic
pc
pa
scan; Eoxpc is the coupled reduction peak potential on the cathodic
scan).
Ta ble 2. Dih ed r a l An gles (d eg) in Neu tr a l Molecu les
15
18
19
20
æ
36.4
8.4
2.8
39.2
17.9
19.4
87.6
35.7
19.3
0
37.1
16.6
22.1
61.1
34.6
15.6
13.7
73.4
37.3
19.4
11.3
73.1
δ1
δ2
θ
79.1
83.7
but no increase is seen for 19. This is consistent with
the shorter bridge of 18 obstructing the marked confor-
mational change which accompanies oxidation to the
dication (see the crystal structure of 182+) whereas the
longer bridge of 19 allows free conformational change.
These observations are in good agreement with the
oxidation potentials of 3a and 3b studied previously.11b
A rise of 300 mV was observed for the short-bridged
system 3a , whereas only a slight rise was seen for 3b
incorporating the longer bridge. The increase in oxidation
potential is obviously more significant when the two
dithiole rings are bridged, since upon oxidation they
undergo a more dramatic conformational change than the
anthracene ring system. Consistent with this, ∆E (de-
and 16 in high yields. Cyclization reactions with 1,4-
benzenedicarbonyl chloride in the presence of triethyl-
amine gave the cyclophane derivatives 18 and 19, in 39
and 28% yields, respectively. The 2 + 2 cyclophane 20
(Chart 2) was also isolated in 23% yield. Compounds 18-
20 are air-stable yellow solids.
The 1H NMR spectrum shows that the 2 + 2 cyclo-
phane 20 is present as two conformers, clearly seen from
the two singlets (each integrating to four protons) arising
from the phenyl protons at 7.98 and 7.94 ppm, respec-
tively. Also the doublets, and the doublet of doublets,
characteristic of 2,6-substituted anthraquinone deriva-
tives, are seen as pairs, indicative of the two conformers.
Another interesting feature of the 1H NMR’s for the
cyclophanes is the chemical shift of the singlet arising
from the phenyl protons. For 18, the short-bridged
cyclophane, the singlet is observed at 6.89 ppm, whereas
for 19 it is at 7.35 ppm. Hence the chemical shift of the
phenyl protons is indicative of the length of the bridge,
and consequently how close the phenyl ring is positioned
to the anthracene ring system, with a change of 1 ppm
from the short-bridged 18 to the longest bridged 2 + 2
cyclophane 20, in which the phenyl rings can be far
removed from the anthracene ring system.
The dication salt 152+(ClO4-)2 was obtained by electro-
crystallization of 15 using tetrabutylammonium per-
chlorate as the electrolyte in dichloromethane. Salt
182+(I3-)2‚(I2)0.5 was obtained by diffusion of iodine vapor
into a solution of 18 in dichloromethane.
Solu tion Electr och em istr y. Solution electrochemical
data, obtained by cyclic voltammetry (CV), are collated
in Table 1. All the nonbridged systems 13-16 showed
the quasireversible two-electron redox wave (neutral f
dication species) typical for 9,10-bis(1,3-dithiol-2-ylidene)-
9,10-dihydroanthracene derivatives,3 but with a positive
shift compared to the unsubstituted system due to the
four electron-withdrawing alkylsulfanyl substituents, a
trend well-known from derivatives of tetrathiafulvalene
(TTF).13 Comparison of cyclophanes 18 and 19 with the
precursors 15 and 16 reveals some interesting trends.
The oxidation potential (Eoxpa) is raised by 50 mV for 18,
fined as Eox - Eoxpc) is significantly reduced for com-
pa
pound 3a (i.e., increased reversibility of the oxidation
process) due to the short bridge preventing a big confor-
mational change, whereas no significant difference in ∆E
is observed for 18 or 19 compared to that of their
precursors. The 2 + 2 cyclophane 20 showed one, slightly
broadened, quasireversible redox wave, presumably a
four-electron process forming the 204+ species. The oxida-
tion potential was raised by 40 mV compared to that of
its precursor 15, which we ascribe to a combination of
intramolecular Coulombic repulsion between the two
dication units and the steric constraints in the oxidized
cyclophane system.
X-r a y Cr ysta l Str u ctu r es. The cyclophanes 18 and
19 and the nonbridged precursor 15 have saddlelike
conformations similar to those described earlier for
nonbridged analogues2 and those with a bridge between
the dithiole rings.11 Molecular structures are shown in
Figure 1, and principal conformational parameters are
given in Table 2. Crystals of 18 and 19 contain no solvent
of crystallization. Folding (æ) of the anthraquinone
moiety along the C(9)...C(10) vector is not affected
significantly by the bridge. Both structures show the
usual packing motif2 of pseudodimers of molecules with
mutually engulfing U-shaped bis(dithiole)anthraquinone
moieties (Figure 2). However, the folding of these moi-
eties is significantly different. The overall measure of the
U-bend, the dihedral angle (θ) between the S(1)C(16)C-
(17)S(2) and S(5)C(21)C(22)S(6) planes in 18 (83.7°) is
within the range (76-92°) observed in nonbridged sys-
tems,2 including 15. In 19 this angle (61.1°) is almost as
(13) Moore, A. J .; Bryce, M. R. J . Chem. Soc., Chem. Commun. 1991,
1638.

3316 J . Org. Chem., Vol. 66, No. 10, 2001
Christensen et al.
F igu r e 2. Crystal packing of 18, showing short S...S contacts
(3.55-3.64 Å).
F igu r e 3. Crystal packing of 15. Molecule A and its inversion
equivalent A′ enclose solvent molecules of CH2Cl2 (C, disorder
not shown) and hexane (D, disordered around an inversion
center). Molecule B and its inversion equivalent B′ form a
mutually engulfing dimer. The apparent gap E is filled by
hydroxyethyleneoxo chains of type B molecules lying above and
below the layer.
center and is chaotically disordered therein (Figure 3).
All the OH groups participate in strong (O...O 2.63-2.79
Å, O-H-O 154-178°) hydrogen bonds with each other.
Dimeric molecule 20 (Figure 4) contains two saddle units
(in approximately parallel orientation) forming mutually
engulfing interactions with two other molecules, related
to the first via different inversion centers (Figure 5).
Intramolecular self-engulfing does not occur. The con-
formations of the two saddle units are very similar; one
of the SMe groups shows a disorder of the sulfur atom.
The structure contains infinite channels, running along
the y axis and filled with chaotically disordered solvent
of crystallization, which we believe to be a mixture of
CH2Cl2 and hexane, partially sharing the same sites. The
volume of the channel and the electron density distribu-
tion are in agreement with a 20:CH2Cl2:hexane stoichi-
ometry of 1:1:1.
F igu r e 1. Molecular structures of 18, 19, and 15, showing
50% thermal ellipsoids.
narrow as in 2a and 2b (46-54°). This illustrates the
flexibility of the saddle conformation and its dependence
on the packing.
Compound 15 crystallizes from dichloromethane/hex-
ane solution as a mixed solvate. The asymmetric unit
comprises two molecules of 15 (A and B), three CH2Cl2
molecules (two of them disordered) and half of a hexane
molecule, which occupies a cavity around an inversion
The asymmetric unit of the iodide salt of 18 comprises
one [18]2+ dication, two triiodide anions, half of an I2

Molecular Saddles. 7
J . Org. Chem., Vol. 66, No. 10, 2001 3317
Ch a r t 3
Waals radius. Correspondingly, the I(1)-I(2) and I(2)-
I(3) bonds in it are practically equal, 2.930(1) and
2.918(1) Å. There is no continuous polyiodide motif.
Oxidation of 18 to 182+ results in a profound electronic
and conformational rearrangement, as in nonbridged
analogues.2a,4 The anthracenediylidene moiety is con-
verted into an aromatic anthracene system the planarity
of which, however, is perturbed by the bridge. Two modes
of distortion of an anthracene system have been observed
earlier. In 9,10-bridged anthracenophanes14a the anthra-
cene system is folded (by æ angle, see above) along the
C(9)...C(10) vector, with the central anthracene ring
adopting a boat conformation. The nonbridged, anthra-
cene systems, which are overcrowded with substituents,
adopt an “end-to-end twist”, measured by the angle (τ)
between the C(2)-C(3) and C(5)-C(6) bonds (τ ) 0 for
the planar anthracene).14b In 3b2+ the bridge between the
dithiole ring effects a minor (æ ) 6°) folding and practi-
cally no end-to-end twist of the anthracene system. In
182+ both the twist (τ ) 7°) and folding (æ ) 22°) are
substantial. Strictly speaking, C(9) and C(10) are not
coplanar with the outer anthracene rings and therefore
the distortion is not a simple folding. It can be described
by the dihedral angles R between the central C(11)C-
(12)C(13)C(14) plane and the C(9)C(11)C(14) or C(10)C-
(12)C(13) planes, the tilting angle â between the latter
two planes and the C(9)-C(15) and C(10)-C(20) bonds,
respectively, and dihedral angles γ between the C(11)C-
(12)C(13)C(14) plane and the planes of the outer anthra-
cene rings. The average R ) 6.8°, â ) 3.6°, and γ ) 11.0°
in 182+ are significantly smaller than those in tetra-
methyl[6]-9,10-anthracenophane (R ) 24.7°, â ) 18.5°,
and γ ) 10.4°) and tetraphenyl[6]-9,10-anthracenophane
(R ) 23.0°, â ) 19.8°, and γ ) 2.4°)14a in which the bond
distances in the outer anthracene rings do not differ from
those in anthracene itself,14c but the bonds between these
rings and C(9) or C(10) are weaker (1.418-1.422 Å vs
1.399 Å in anthracene), due to the nonplanarity interfer-
F igu r e 4. Molecular structure of 20. The minor position of
the disordered S(7) atom and all H atoms are omitted.
F igu r e 5. Crystal packing of 20.
ing with the p-orbital overlap. In the less distorted 182+
,
these bonds (ii, see Table 3 and Chart 3) average 1.41(1)
Å. The bridging benzene ring is practically parallel and
eclipsed with the central anthracene ring, resulting in
intramolecular contacts C(13)...C(31) 3.58, C(10)...C(33)
3.60, and C(11)...C(34) 3.56 Å, while in neutral 18 and
19 this benzene ring is inclined to the C(11)C(12)C(13)C-
(14) plane by 60° and 79°, respectively.
The asymmetric unit of the salt 152+(ClO4-)2 comprises
one 152+ dication, two perchlorate anions, and one CH2-
Cl2 molecule (Figure 7). Intermolecular hydrogen bonds
O(2)-H...O(4) and O(4)-H...O(1) (O...O 2.93 and 2.84 Å,
O-H-O 149-161°) link cations (related by the b trans-
lation) into an infinite chain, parallel to the y axis. In
F igu r e 6. Asymmetric unit of 182+(I3-)2‚(I2)0.5‚CH2Cl2 [I(7′)
is related to I(7) by an inversion center], showing 50% thermal
ellipsoids. Angles in degrees: I(1)-I(2)-I(3) 176.94(3), I(4)-
I(5)-I(6) 175.19(3), I(5)-I(6)-I(7) 107.66(4), I(6)-I(7)-I(7′)
168.29(6).
molecule (which is situated at an inversion center), and
one disordered CH2Cl2 molecule (Figure 6). The iodine
molecule has a I(7)-I(7′) bond distance of 2.766 Å and
forms secondary bonds I(6)...I(7) 3.378(2) Å with two
anions, causing considerable asymmetric bond distances
therein: I(4)-I(5) 2.873(2) vs I(5)-I(6) 2.988(2) Å. The
shortest I...I contact formed by the other independent
anion, I(3)...I(7) of 4.30 Å, is equal to double the van der
(14) (a) Tobe, Y.; Saiki, S.; Utsumi, N.; Kusumoto, T.; Ishii, H.;
Kakiuchi, K.; Kobiro, K.; Naemura, K. J . Am. Chem. Soc. 1996, 118,
9488. (b) Pascal, R. A.; McMillan, W. D.; van Engen, D.; Eason, R. G.
J . Am. Chem. Soc. 1987, 109, 4660. (c) Pratt Brock, C.; Dunitz, J . D.
Acta Crystallogr. 1990, B46, 795.

3318 J . Org. Chem., Vol. 66, No. 10, 2001
Christensen et al.
Con clu sion s
The cyclophanes 18-20 have been synthesized by
macrocyclization reactions of building blocks 15 and 16,
thereby providing a new structural modification of the
9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene sys-
tem. These are fundamentally interesting and unusual
molecules by virtue of the combination of redox and
structural properties which they display. This work paves
the way for the synthesis of more elaborate caged and
bridged structures on the basis of synthetic modifications
and electrochemical manipulation of these versatile
extended π-electron systems.
Exp er im en ta l Section
Gen er a l P r oced u r es. All solvents were dried and distilled
before use.
F igu r e 7. Asymmetric unit of 152+(ClO4-)2‚CH2Cl2, showing
50% thermal ellipsoids.
1-Ch lor o-2-{2-[(ter t-b u t yld ip h en ylsilyl)oxy]et h oxy}-
eth a n e (7). To a solution of 2-(2-chloroethoxy)ethanol 5 (9.97
g, 80.0 mmol) and imidazole (27.2 g, 400 mmol) in dry DMF
(50 mL) was added tert-butyldiphenylchlorosilane (20.61 g,
75.0 mmol), and the reaction was stirred for 16 h at room
temperature. The solution was poured onto water (500 mL)
and extracted with hexane. The combined organic phases were
washed with brine, dried (MgSO4), and concentrated in vacuo
to give a yellow oil. Purification by chromatography using a
short column (silica gel, dichloromethane-hexane, 1:3 v/v)
Ta ble 3. Aver a ge Bon d Dista n ces
15
152+
18
182+
19
20
i
ii
1.417(4) 1.435(6) 1.420(2) 1.45(1)
1.482(4) 1.405(6) 1.481(2) 1.41(1)
iii 1.361(4) 1.487(6) 1.364(2) 1.50(1)
1.412(2) 1.415(8)
1.483(2) 1.462(8)
1.359(2) 1.352(8)
iv
v
vi
1.769(3) 1.686(5) 1.772(1) 1.678(8) 1.774(2) 1.762(6)
1.759(3) 1.719(5) 1.757(1) 1.717(7) 1.763(2) 1.752(7)
1.343(4) 1.376(6) 1.347(2) 1.38(1)
1.346(2) 1.328(9)
1
vii 1.753(3) 1.733(5)a 1.753(1) 1.740(8)a 1.757(2) 1.749(8)
afforded 7 as a colorless oil (24.47 g, 90%). H NMR (CDCl3):
1.760(5)b
δ 7.72-7.70 (4H, m), 7.44-7.40 (6H, m), 3.84 (2H, t, J ) 5.6
Hz), 3.77 (2H, t, J ) 6.0 Hz), 3.64 (2H, t, J ) 5.6 Hz), 3.61
(2H, t, J ) 6.0 Hz), 1.08 (9H, s). 13C NMR (CDCl3): δ 135.6,
133.5, 129.6, 127.6, 72.5, 71.4, 63.5, 42.8, 26.8, 19.2. MS (CI)
viii 1.805(4) 1.797(5)a 1.812(2) 1.799(9)a 1.811(2) 1.793(9)
1.814(5)b
a
b
In-plane SMe group. Out-of-plane SMe group.
m/z (%) 380 (67, MNH4+), 285 (100). Anal. Calcd for C20H27
-
ClO2Si (MW 362.97): C, 66.18; H, 7.50. Found: C, 66.04; H,
7.45.
contrast with 182+, the anthracene moiety in 152+ is not
folded along the C(9)...C(10) vector, but the end-to-end
twist (τ ) 10.6°) is even stronger than in the former,
although the bridge is absent. Both dithiolium rings are
planar and nearly coplanar (within 5°) and both are
nearly perpendicular to the mean plane of the anthracene
moiety, forming dihedral angles of 78° and 83° with it.
The O(1)C(25)C(26) and O(3)C(27)C(28) side chains are
essentially coplanar with the anthracene system, while
the O(2)H and O(4)H hydroxy groups are oriented out of
the plane on the same side of it. The asymmetric unit
contains six cation-anion S...O contacts shorter than the
standard van der Waals distance of 3.25 Å, the shortest
being S(6)...O(8) 3.01 Å and S(2)...O(9) 3.08 Å.
1-Iod o-2-{2-[(t er t -b u t yld ip h e n ylsilyl)oxy]e t h oxy }-
eth a n e (8). To a solution of 1-chloro-2-{2-[(tert-butyldiphenyl-
silyl)oxy]ethoxy}ethane 7 (24.30 g, 67 mmol) in dry 2-butanone
(100 mL) was added sodium iodide (15.0 g, 100 mmol). The
suspension was refluxed under argon for 48 h, concentrated
in vacuo, and redissolved in dichloromethane (300 mL). The
solution was washed with water and brine, dried (MgSO4), and
filtered through a plug of silica. Evaporation of the solvent in
vacuo afforded 8 as a colorless oil (29.80 g, 98%). 1H NMR
(CDCl3): δ 7.72-7.70 (4H, m), 7.44-7.38 (6H, m), 3.83 (2H, t,
J ) 5.0 Hz), 3.77 (2H, t, J ) 6.5 Hz), 3.63 (2H, t, J ) 5.0 Hz),
3.23 (2H, t, J ) 6.5 Hz), 1.08 (9H, s). 13C NMR (CDCl3): δ
135.6, 133.5, 129.6, 127.6, 72.1, 72.0, 63.5, 26.8, 19.1, 3.1. MS
(CI) m/z (%) 472 (48, MNH4+), 251 (100). Anal. Calcd for C20H27
-
IO2Si (MW 454.42): C, 52.86; H, 5.99. Found: C, 52.95; H,
5.98.
As would be expected, the C-S bonds in the dithiole
rings are shortened, and the CdC bond lengthened on
oxidation, as the ring acquires more aromatic character
(Table 3 and Chart 3). It is interesting that while in the
neutral systems the inner C-S bonds iv are longer than
the outer ones v, for the cations the opposite is true. The
2,6-B i s {2-[(t er t -b u t y ld i p h e n y ls i ly l)o x y ]e t h o x y }-
a n th r a qu in on e (10). To a mixture of 1-bromo-2-[(tert-butyl-
diphenylsilyl)oxy]ethane 6 (prepared by direct analogy with
7 which is a modification of the literature route)15 (16.35 g,
45.0 mmol) and potassium carbonate (4.15 g, 30.0 mmol) in
dry degassed DMF (20 mL) was added anthraflavic acid 9 (3.60
g, 15.0 mmol). The reaction mixture was stirred under argon
at 100 °C for 16 h, which made the color change from yellow
to dark red, diluted with dichloromethane (300 mL), and
washed with brine. The organic phase was dried (MgSO4) and
filtered through a plug of silica to give a yellow solution, which
was concentrated in vacuo. The oily residue was purified by
column chromatography (silica gel, dichloromethane-hexane,
1:1 v/v), and concentration in vacuo of the first yellow fraction
afforded 10 as a pale yellow solid (9.18 g, 76%), mp 133-134
°C. 1H NMR (CDCl3): δ 8.23 (2H, d, J ) 8.8 Hz), 7.80-7.78
(8H, m), 7.72 (2H, d, J ) 2.4 Hz), 7.47-7.42 (12H, m), 7.19
(2H, dd, J 1 ) 2.4 Hz, J 2 ) 8.8 Hz), 4.29 (4H, t, J ) 4.8 Hz),
conformations of the SMe groups are noteworthy. In 152+
,
one SMe substituent at each dithiolium ring is coplanar
with the ring and the other nearly perpendicular to it
(torsion angles 9.4°, 2.1°, 82.7°, and 85.2°, respectively);
bonds vii for the in-plane ligands are substantially
shorter (and viii slightly shorter) than for the out-of-plane
ones, indicating uneven conjugation. In 182+, all SMe
groups adopt in-plane conformations, and bond distances
are in agreement with those for similar groups in 152+
.
On the other hand, in the neutral systems there is no
correlation between the Me-S-CdC torsion angles
(varying from 178° to 102°) and the fairly constant C-S
bond lengths.
(15) Paquette, L. A.; Doherty, A. M.; Rayner, C. M. J . Am. Chem.
Soc. 1992, 114, 3910.

Molecular Saddles. 7
J . Org. Chem., Vol. 66, No. 10, 2001 3319
4.10 (4H, t, J ) 4.8 Hz), 1.14 (18H, s). 13C NMR (CDCl3): δ
181.8, 163.6, 135.6, 135.5, 133.2, 129.7, 129.5, 127.6, 126.9,
120.7, 110.5, 69.6, 62.3, 26.7, 19.1. MS (CI) m/z (%) 805 (13,
MH+), 747 (20), 729 (100). Anal. Calcd for C50H52O6Si2 (MW
805.12): C, 74.59; H, 6.51. Found: C, 74.32; H, 6.56.
dichloromethane (200 mL), washed with water and brine, dried
(MgSO4), and concentrated in vacuo. Chromatography using
a short column (silica gel, dichloromethane until no more
byproducts were visible on the column, then dichloromethane-
ethyl acetate, 3:1 v/v) afforded 15 as a yellow solid (0.938 g,
93%), mp 147-150 °C. Yellow-brown prisms, suitable for X-ray
crystallographic analysis, were grown by slow diffusion of
hexane into a solution of 15 in dichloromethane. 1H NMR
(CDCl3): δ 7.44 (2H, d, J ) 8.8 Hz), 7.08 (2H, d, J ) 2.4 Hz),
6.84 (2H, dd, J 1 ) 2.4 Hz, J 2 ) 8.8 Hz), 4.15 (4H, t, J ) 4.8
2,6-Bis{2-{2-[(t er t -b u t yld ip h e n ylsilyl)oxy]e t h oxy}-
eth oxy}a n th r a qu in on e (11). By a procedure similar to the
synthesis of 10, compound 11 was obtained from the reaction
of anthraflavic acid 9 (3.60 g, 15.0 mmol) with 1-iodo-2-{2-
[(tert-butyldiphenylsilyl)oxy]ethoxy}ethane 8 (16.35 g, 45.0
mmol) in the presence of potassium carbonate (4.15 g, 30.0
mmol). Purification by column chromatography (silica gel,
dichloromethane) afforded 11 as a pale yellow solid (11.64 g,
Hz), 4.01 (4H, t, J ) 4.8 Hz), 2.39 (12H, s), 1.94 (2H, br s). 13
C
NMR (CDCl3): δ 156.9, 136.3, 129.6, 128.0, 126.7, 126.3, 125.3,
123.2, 112.0, 111.6, 69.4, 61.4, 19.2, 19.1. UV-vis (CH2Cl2):
1
87%), mp 103-104 °C. H NMR (CDCl3): δ 8.22 (2H, d, J )
λmax (lg e) 432 (4.40), 364 (4.18) nm. MS (EI) m/z (%) 684 (100,
8.8 Hz), 7.72 (2H, d, J ) 2.8 Hz), 7.70-7.68 (8H, m), 7.42-
7.34 (12H, m), 7.24 (2H, dd, J 1 ) 2.8 Hz, J 2 ) 8.8 Hz), 4.26
(4H, t, J ) 4.6 Hz), 3.91 (4H, t, J ) 4.6 Hz), 3.85 (4H, t, J )
5.2 Hz), 3.69 (4H, t, J ) 5.2 Hz), 1.05 (18H, s). 13C NMR
(CDCl3): δ 182.2, 163.7, 135.7, 135.6, 133.6, 129.6, 129.6, 127.6,
127.2, 121.2, 110.5, 72.7, 69.4, 68.2, 63.5, 26.8, 19.2. MS (CI)
m/z (%) 910 (10, MNH4+), 815 (35). Anal. Calcd for C54H60O8-
Si2 (MW 893.22): C, 72.61; H, 6.77. Found: C, 72.52; H, 6.76.
2,6-Bis{2-[(ter t-b u t yld ip h en ylsilyl)oxy]et h oxy}-9,10-
b is[4,5-b is(m et h ylt h io)-1,3-d it h iol-2-ylid en e]-9,10-d ih y-
d r oa n th r a cen e (13). To a solution of the phosphonate ester
1212 (1.72 g, 5.66 mmol) in dry tetrahydrofuran (100 mL) at
-78 °C under argon was added lithium diisopropylamide (4.14
mL, 6.22 mmol of a 1.5 M solution) via syringe, and the
resultant cloudy yellow mixture was stirred for 2 h at -78 °C.
Compound 10 (1.90 g, 2.36 mmol) was dissolved in dry THF
(30 mL) and added to the reaction mixture via a syringe over
15 min. The reaction mixture was stirred at -78 °C for another
2 h, whereupon it was allowed to slowly attain room temper-
ature for 12 h. Evaporation of the solvent gave a red residue
which was dissolved in dichloromethane (200 mL), washed
with water and brine, dried (MgSO4), and concentrated in
vacuo. Column chromatography (silica gel, dichloromethane-
hexane, 1:1 v/v) afforded 13 as a yellow foam (1.89 g, 69%),
mp 82-85 °C. 1H NMR (CDCl3): δ 7.78-7.76 (8H, m), 7.48
(2H, d, J ) 8.4 Hz), 7.46-7.40 (12H, m), 7.12 (2H, d, J ) 2.8
Hz), 6.84 (2H, dd, J 1 ) 2.8 Hz, J 2 ) 8.4 Hz), 4.23-4.16 (4H,
m), 4.07 (4H, t, J ) 5.2 Hz), 2.41 (6H, s), 2.37 (6H, s), 1.12
(18H, s). 13C NMR (CDCl3): δ 157.1, 136.2, 135.6, 133.4, 129.6,
129.1, 127.7, 127.5, 126.5, 125.7, 125.5, 123.5, 111.9, 111.7,
69.2, 62.6, 26.8, 19.2, 19.0, 19.0. MS (CI): m/z ) 1161 (13,
MH+), 283 (100). Anal. Calcd for C60H64O4S8Si2 (MW
1161.85): C, 62.03; H, 5.55. Found: C, 61.65; H, 5.54.
M+). Anal. Calcd for C28H28O4S8 (MW 685.05): C, 49.09; H,
4.12. Found: C, 49.10; H, 4.20.
2,6-Bis[2-(2-h yd r oxyet h oxy)et h oxy]-9,10-b is[4,5-b is-
(m eth ylth io)-1,3-d ith iol-2-ylid en e]-9,10-d ih yd r oa n th r a -
cen e (16). By a procedure similar to that for the conversion
of 13 to 15, compound 14 (5.00 g, 4.00 mmol) was treated with
tetrabutylammonium fluoride (12.0 mL, 12.0 mmol of a 1.0 M
solution in THF) to form 16. Purification by chromatography
using a short column (silica gel, dichloromethane until no more
byproducts were visible on the column, then ethyl acetate)
afforded 16 as a yellow solid (2.68 g, 87%), mp 204-205 °C.
1H NMR (CDCl3): δ 7.43 (2H, d, J ) 8.8 Hz), 7.07 (2H, d, J )
2.8 Hz), 6.84 (2H, dd, J 1 ) 2.4 Hz, J 2 ) 8.4 Hz), 4.20 (4H, t, J
) 4.8 Hz), 3.90 (4H, t, J ) 4.8 Hz), 3.78 (4H, t, J ) 4.8 Hz),
3.69 (4H, t, J ) 4.8 Hz), 2.38 (12H, s), 1.98 (2H, br s). 13C NMR
(CDCl3): δ 156.9, 136.3, 129.4, 127.8, 126.6, 126.3, 125.3, 123.3,
112.2, 111.6, 72.6, 69.6, 67.6, 61.8, 19.2, 19.1. UV-vis (CH2-
Cl2): λmax (log ꢀ) 432 (4.41), 364 (4.18) nm. MS (EI) m/z (%)
772 (100, M+). Anal. Calcd for C32H36O6S8 (MW 773.15): C,
49.71; H, 4.69. Found: C, 49.77; H, 4.73.
Cyclop h a n e (18) a n d Cyclop h a n e (20). To a solution of
dialcohol 15 (0.300 g, 0.438 mmol) and 1,4-benzenedicarbonyl
chloride 17 (0.089 g, 0.438 mmol) in dry dichloromethane (300
mL) was added triethylamine (0.50 mL, excess), and the
reaction was stirred under argon for 16 h at room temperature.
The solution was concentrated in vacuo and the orange residue
purified by column chromatography (silica gel, dichloromethane).
The fractions containing the first yellow band were concen-
trated in vacuo to give 18 as a yellow powder (0.141 g, 39%).
Orange-yellow prisms, suitable for X-ray crystallographic
analysis, were grown by slow diffusion of hexane into a solution
of 18 in dichloromethane, mp >260 °C. 1H NMR (CDCl3): δ
7.38 (2H, d, J ) 8.4 Hz), 7.36 (2H, d, J ) 2.4 Hz), 6.95 (2H,
dd, J 1 ) 2.4 Hz, J 2 ) 8.4 Hz), 6.89 (4H, s), 4.67-4.55 (6H, m),
4.47-4.41 (2H, m), 2.39 (6H, s), 2.38 (6H, s). 13C NMR
(CDCl3): δ 165.0, 158.3, 136.6, 132.9, 130.1, 128.8, 128.7, 126.6,
125.9, 125.6, 122.5, 115.3, 114.2, 67.0, 66.2, 19.1, 19.0. UV-
vis (CH2Cl2): λmax (log ꢀ) 436 (4.55), 368 (4.36) nm. MS (EI)
m/z (%) 814 (100, M+). Anal. Calcd for C36H30O6S8 (MW
815.15): C, 53.04; H, 3.71. Found: C, 52.81; H, 3.68.
The second yellow broad band was collected, concentrated
in vacuo, and recolumned (silica gel, dichloromethane-ethyl
acetate 98:2 v/v), affording 20 as a yellow powder (0.083 g,
23%), mp 222-227 °C (dec). Orange prisms, suitable for X-ray
crystallographic analysis, were grown by slow diffusion of
hexane into a solution of 20 in dichloromethane. 1H NMR
(CDCl3): δ 7.98 (4H, s), 7.94 (4H, s), 7.412 (2H, d, J ) 8.4
Hz), 7.408 (2H, d, J ) 8.8 Hz), 7.10 (4H, d, J ) 2.4 Hz), 6.87
(2H, dd, J 1 ) 2.8 Hz, J 2 ) 8.4 Hz), 6.85 (2H, dd, J 1 ) 2.8 Hz,
J 2 ) 8.4 Hz), 4.76-4.68 (8H, br m), 4.42-4.38 (8H, br m),
2.34-2.33 (24H, m). UV-vis (CH2Cl2): λmax (log ꢀ) 432 (4.73),
368 (4.53) nm. MS (EI) m/z (%) 1628 (1, M+), 1627 (2), 182
(100). Anal. Calcd for C72H60O12S16 (MW 1630.30): C, 53.04;
H, 3.71. Found: C, 52.77; H, 3.67.
Cyclop h a n e (19). By a procedure similar to that for the
conversion of 15 to 18, dialcohol 16 (0.250 g, 0.320 mmol) was
reacted with 1,4-benzenedicarbonyl chloride 17 (0.066 g, 0.320
mmol) in the presence of excess triethylamine. Purification by
column chromatography (silica gel, dichloromethane-ethyl
acetate, 95:5 v/v) afforded 19 as a yellow powder (0.083 g, 28%).
Yellow prisms, suitable for X-ray crystallographic analysis,
2,6-Bis{2-{2-[(t er t -b u t yld ip h e n ylsilyl)oxy]e t h oxy}-
eth oxy}-9,10-bis[4,5-bis(m eth ylth io)-1,3-dith iol-2-yliden e]-
9,10-d ih yd r oa n th r a cen e (14). This procedure is similar to
the synthesis of 13. The phosphonate ester 1212 (4.00 g, 13.1
mmol) was deprotonated using lithium diisopropylamide (9.60
mL, 14.4 mmol of a 1.5 M solution) and reacted with compound
11 (4.70 g, 5.26 mmol). Purification by column chromatography
(silica gel, dichloromethane-hexane, 3:1 v/v) afforded 14 as a
1
yellow foam (5.33 g, 81%), mp 51-54 °C. H NMR (CDCl3): δ
) 7.71-7.68 (8H, m), 7.43 (2H, d, J ) 8.8 Hz), 7.41-7.34 (12H,
m), 7.07 (2H, d, J ) 2.4 Hz), 6.83 (2H, dd, J 1 ) 2.4 Hz, J 2
)
8.8 Hz), 4.15 (4H, t, J ) 4.8 Hz), 3.89-3.84 (8H, m), 3.69 (4H,
t, J ) 5.2 Hz), 2.38 (6H, s), 2.34 (6H, s), 1.06 (18H, s). 13C
NMR (CDCl3): δ 157.1, 136.2, 135.6, 133.6, 129.6, 129.2, 127.7,
127.6, 126.6, 126.1, 125.4, 123.5, 112.2, 111.5, 72.7, 69.7, 67.7,
63.5, 26.8, 19.2, 19.2, 19.1. MS (CI): m/z ) 1249 (14, MH+),
283 (100). Anal. Calcd for C64H72O6S8Si2 (MW 1249.95): C,
61.50; H, 5.81. Found: C, 61.23; H, 5.84.
2,6-Bis(2-h yd r oxyeth oxy)-9,10-bis[4,5-bis(m eth ylth io)-
1,3-d ith iol-2-ylid en e]-9,10-d ih yd r oa n th r a cen e (15). Com-
pound 13 (1.70 g, 1.47 mmol) was dissolved in dry THF (20
mL) and stirred under argon at room temperature. A solution
of tetrabutylammonium fluoride (4.40 mL, 4.40 mmol of a 1.0
M solution in THF) was added dropwise via a syringe over 15
min, causing the reaction mixture to change color from yellow
to brown. Further stirring for 1.5 h, followed by addition of a
few drops of water (0.1 mL) and evaporation of the solvent,
afforded a brown residue. The residue was dissolved in

3320 J . Org. Chem., Vol. 66, No. 10, 2001
Christensen et al.
were grown by slow diffusion of hexane into a solution of 19
in dichloromethane, mp 209-211 °C. 1H NMR (CDCl3): δ 7.35
(4H, s), 7.26 (2H, d, J ) 3.2 Hz), 7.20 (2H, d, J ) 8.4 Hz), 6.70
(2H, dd, J 1 ) 2.4 Hz, J 2 ) 8.4 Hz), 4.58-4.54 (2H, m), 4.41-
4.37 (2H, m), 4.31-4.28 (4H, m), 4.06-4.02 (2H, m), 3.92-
3.83 (6H, m), 2.373 (6H, s), 2.367 (6H, s). 13C NMR (CDCl3):
δ 165.6, 157.3, 136.0, 133.0, 129.0, 128.9, 127.5, 126.3, 126.2,
125.3, 123.6, 113.2, 111.9, 70.1, 69.6, 69.2, 64.8, 19.2, 19.0.
UV-vis (CH2Cl2): λmax (log ꢀ) 432 (4.58), 364 (4.37) nm. MS
(EI) m/z (%) 902 (100, M+). Anal. Calcd for C40H38O8S8 (MW
903.25): C, 53.19; H, 4.24. Found: C, 52.87; H, 4.21.
full sphere of the reciprocal space was covered by a combina-
tion of five sets of ω scans; each set at different æ and/or 2θ
angles; for the rest, more than hemisphere was covered by four
sets. Reflection intensities were integrated using SAINT
program16 and corrected for absorption by numerical integra-
tion methods (based on crystal face indexing) for 18, 19, 182+
,
and 152+ or by semiempirical method (comparison of Laue
equivalents)17 for 15. The structures were solved by direct
methods and refined by full-matrix least squares against F2
of all data, using SHELXTL software.18 Crystal data and
experimental details are summarized in Table 4 (Supporting
Information), and atomic coordinates, thermal parameters, and
bond distances and angles have been deposited at the Cam-
bridge Crystallographic Data Centre.19
P r ep a r a t ion of 152+(ClO4-)2. Dry tetrabutylammonium
perchlorate (50 mg) was added to each chamber of a glass
electrocrystallization cell, in which the two chambers were
separated by a glass frit, and the cell was flushed with argon.
Compound 15 (5 mg) was placed in the anodic chamber, and
dry degassed dichloromethane (7 mL) was added to each
chamber of the cell. The platinum electrodes were mounted,
sealing the solutions from the atmosphere. A potential of 1.0
V was applied, which provided an initial current of 1.0 µA.
The cell was stored in the dark for 14 days at 20 °C, during
which time the current dropped to 0.2 µA and red needles of
152+(ClO4-)2 (up to 5 mm in length) grew on the anode. The
crystals, which were suitable for X-ray crystallography, were
harvested and washed with dry dichloromethane.
Ack n ow led gm en t. We thank EPSRC and the Dan-
ish Research Academy (C.A.C.) for funding. J .A.K.H.
thanks the EPSRC for a Senior Research Fellowship.
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra of
compounds 7, 8, 10, 11, 13, 14, 15, 16, 18, 19, and 20 and the
crystallographic data for 15, 152+(ClO4-)2, 18, 182+(I3-)2‚(I2)0.5
,
19, and 20. This material is available free of charge via the
Internet at http://pubs.acs.org.
P r ep a r a tion of 182+(I3-)2(I2)0.5CH2Cl2. A 10 mM solution
of cyclophane 18 (2 mL) in dichloromethane was placed in a 5
mL open sample vial which was placed in a sealed 250 mL
sample vial containing iodine crystals (0.5 g). Diffusion of
iodine vapor into the solution of 18 gave black shiny needles
suitable for X-ray crystallographic analysis, mp 195-197 °C
(dec). Anal. Calcd for C36H30O6S8(I3)2(I2)0.5CH2Cl2: C, 24.85; H,
1.80. Found: C, 24.95; H, 1.75.
Cr ysta l Str u ctu r e An a lyses. X-ray diffraction experi-
ments were carried out on a SMART 3-circle diffractometer
with a 1K CCD area detector, using graphite-monochromated
Mo KR radiation (λh ) 0.71073 Å) and a Cryostream (Oxford
Cryosystems) open-flow N2 gas cryostat. For 18 and 19, the
J O001524K
(16) SMART & SAINT, Area detector control & integration software,
Ver. 6.01. Bruker Analytical X-ray Systems, Madison, WI, 1999.
(17) Sheldrick, G. M. SADABS: Program for scaling and correction
of area detector data. University of Go¨ttingen, Germany, 1996.
(18) SHELXTL, An integrated system for solving, refining and
displaying crystal structures from diffraction data, Ver. 5.10. Bruker
Analytical X-ray Systems, Madison, WI, 1997.
(19) Supplementary publication nos. CCDC-137171, 149466, 137172,
149465, 149467, and 149468 for 15, 152+, 18, 182+, 19, and 20,
respectively, can be obtained on request from the Director, Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge, CB2 1EZ,
U.K.