New chiral organosulfur donors related to bis(ethylenedithio) tetrathiafulvalene

Article abstract of DOI:10.1016/j.tet.2010.06.034

Six new enantiopure chiral organosulfur donors, with structures related to BEDT-TTF, have been synthesised for use in the preparation of organic metals, starting either by double nucleophilic substitutions on the bis-mesylate of 2R,4R-pentane-2,4-diol or by a cycloaddition with subsequent elimination of acetic acid on the enol acetate of (+)-nopinone. Crystal structures of some of their radical cation triiodides salts and TCNQ complexes are reported.

Full text of DOI:10.1016/j.tet.2010.06.034

Tetrahedron 66 (2010) 6977e6989
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
New chiral organosulfur donors related to bis(ethylenedithio)tetrathiafulvalene
,
Songjie Yang a, Andrew C. Brooks a b, Lee Martin a, Peter Day b, Melanie Pilkington c, William Clegg d,
,
Ross W. Harrington d, Luca Russo d, John D. Wallis a
*
a School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK
b University College London, Department of Chemistry, 20 Gordon Street, London WC1H 0AJ, UK
c Department of Chemistry, Brock University, 500 Glenridge Ave, St Catherines, Ontario, Canada L2S 3A1
d School of Chemistry, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Six new enantiopure chiral organosulfur donors, with structures related to BEDT-TTF, have been syn-
thesised for use in the preparation of organic metals, starting either by double nucleophilic substitutions
on the bis-mesylate of 2R,4R-pentane-2,4-diol or by a cycloaddition with subsequent elimination of
acetic acid on the enol acetate of (þ)-nopinone. Crystal structures of some of their radical cation triio-
dides salts and TCNQ complexes are reported.
Received 25 November 2009
Received in revised form 31 May 2010
Accepted 14 June 2010
Available online 18 June 2010
Crown Copyright Ó 2010 Published by Elsevier Ltd. All rights reserved.
S
S
S
S
1. Introduction
S
S
S
S
S
S
S
S
The radical cation salts and charge transfer molecular complexes
of TTF 1 and BEDT-TTF 2 show a wide range of electrical behaviour,
and have found use in a range of systems including metallic sys-
tems, semiconductors and low-temperature superconductors.1
Introduction of chirality into the system may be expected to
introduce further effects. Indeed, Rikken has demonstrated
the phenomenon of magneto-chiral anisotropy in carbon nano-
tubes, i.e., that in a coaxial magnetic field the resistance to current
flow along nanotubes with enantiomeric structures are different.2
Furthermore, one could anticipate that chirality may modulate
the Hall effect, in which the path of an electric current travelling in
a perpendicular magnetic field is displaced in a direction perpen-
dicular to both that of the current and the magnetic field. The
challenge is to prepare molecular materials in which the current
can flow in a chiral environment, and the state of progress has been
reviewed recently.3 In one approach several enantiopure organo-
sulfur donors have been prepared, including donors with chiral
sidechains e.g., 3e4,4 BEDT-TTF derivatives with stereogenic carbon
atoms in the molecular skeleton, e.g., 5e85e10, EDT-TTF derivatives
containing a chiral oxazoline group such as 9,11 and an enan-
tioenriched donor 10 containing a stereogenic sulfur atom.12
A small number of radical cation salts of enantiopure donors have
now been characterised and in two cases, (6)2PF6 and (9)2AsF6,
a comparison made between enantiomeric and racemic mate-
rials.7,10 In the former, stacks of donors on either side of the anions
are related by a centre of symmetry in the racemate and by a two-
2
1
MeO2
C
S
S
H
H
CH3
Ph
S
OC12H25
OC12H25
S
S
S
S
H3C
N
N
S
S
S
Ph
MeO2C
4
3
S
S
S
S
CH3
CH3
H3C
H3C
S
S
S
CH3
S
S
S
S
S
S
S
S
S
CH3
6
5
OH
S
S
S
S
HO
HO
S
S
S
S
S
S
S
S
CH3O2
C
S
S
S
S
OH
8
7
O
S
O
S
S
S
S
S
S
S
S
S
N
S
S
S
S
10
9
fold rotation axis in the enantiopure salt but the salts have similar
conductivities;8 however, in the latter the enantiopure material
shows a room temperature conductivity an order of magnitude
higher than for the racemate, due to disorder in the racemate,11
* Corresponding author. E-mail address: john.wallis@ntu.ac.uk (J.D. Wallis).
0040-4020/$ e see front matter Crown Copyright Ó 2010 Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.06.034

6978
S. Yang et al. / Tetrahedron 66 (2010) 6977e6989
MeO
however no suitable system has been found so far in which chirality
is strongly expressed in the packing arrangement. Other ap-
proaches for incorporating chirality into such salts are to use either
O
O
a chiral anion such as tris(oxalato)Cr(III)13 or [Sb2( -tartrate)2]2e14
L
S
S
S
S
S
S
S
S
O
O
or to introduce an enantiopure solvent molecule in the salt’s
crystal structure.15 The arrangement of donors in
a
helical
arrangement is a particularly attractive goal, and has been partially
achieved by supramolecular organisation of donor pairs in the TTF
mellitate salt.16
17
MeO
Me
Me
Me
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
X
X
X
X
Me
Me
Me
11
12
S
Me
Me
S
S
S
S
S
S
S
S
S
S
S
S
S
S
Me
Me
18 X = H
19 X = F
S
S
13
14
Me
Me
OH
OH
Me
S
S
S
S
Me
S
S
S
S
S
S
S
OH
OH
S
S
S
S
The synthesis of donor 11 started with the cyclisation of the
dithiolate 20, prepared in three steps from carbon disulfide,18 with
the bis-mesylate of R,R-pentane-2,4-diol (Scheme 1). The first
mesylate group is substituted by reaction in methanol at room
temperature, but it was necessary to replace the methanol with THF
and heat to reflux to complete the cyclisation to give the thione 21
in 45% yield. The thione was converted to oxo compound 22 using
mercuric acetate in quantitative yield, and this was then homo-
coupled in refluxing trimethyl phosphite over 24 h to give 11 in 75%
yield. Cross-coupling, under similar conditions, of oxo compound
22 with a three-fold excess of the unsubstituted thione 23 yielded
the cross-coupled donor 12 in 22% yield after chromatography. The
low yield of 12 is a consequence of the faster homocoupling of
thione 23 to give BEDT-TTF.
Me
Me
S
15
16
Here we report the synthesis of a group of novel chiral orga-
nosulfur donors, 11e16, in which chirality is provided by one or
more hydrocarbon groupings. The structures of products from ini-
tial experiments to form charge transfer complexes are also
described.
2. Discussion
2.1. Synthesis of 11 and 12
The molecular structures of donors 11 and 12 were determined
by X-ray crystallography. For both donors the seven-membered
rings adopt chair conformations with one methyl group in an axial
position and one in an equatorial position. For the homocoupled
donor 11 (Fig. 2) the structure of the organosulfur system deviates
very strongly from planarity, with the plane of the central S2C]CS2
grouping lying at 31.8ꢀ and 35.2ꢀ to the planes defined by the SeC]
CeS groupings of the outer dithiepine rings, to give the molecule
a strongly bowed structure. The structure of the cross-coupled
donor 12 (Fig. 3) is not so bowed, with the plane of the central S2C]
CS2 grouping lying at 19.2ꢀ to the dithiepine SeC]CeS plane and at
19.7ꢀ to the dithiin SeC]CeS plane. All bond angles in the seven-
membered rings of 11 and 12 are widened: at sp2 C atoms: [11:
127.47(10)e127.84(10), 12: 125.90(9)e126.23(9)ꢀ], at S atoms [11:
102.94(6)e105.93(6), 12: 103.65(5)e105.43(5)ꢀ], at methine C
atoms [11: 113.33(9)e115.62(9), 12:113.54(8)e114.90(8)ꢀ], and es-
pecially at the methylene C atoms [11: 117.33(11)e117.64(10), 12:
117.92(10)ꢀ]. However, there is no indication of significant strain on
the bond lengths in this ring, e.g., sp3Cesp3C [11: 1.5244(18)e
1.5292(18), 12: 1.5278(16)e1.5304(17) Å], and as expected CeS
bonds to sp3C [11: 1.8259(13)e1.8400(12), 12: 1.8301(12)e1.8327
(13) Å] are longer than those to sp2C [11: 1.7438(13)e1.7459(13),
12: 1.7441(11)e1.7451(12) Å]. Despite the non-planarity of these
donors, it is envisaged that, on formation of radical cation salts, the
organosulfur region of the molecule will be closer to planarity.
Electrocrystallisation of the enantiopure donor (S,S,S,S)-tetra-
methylBEDT-TTF 5 has given a series of radical cation salts, but their
crystal structures were pseudocentrosymmetric, with the methyl
groups adopting equatorial orientations.6 However, we reasoned
that insertion of a methylene group between each pair of stereo-
genic centres to give 11 would provide a more promising system.
The outer seven-membered rings of donor 11 would be expected to
adopt chair conformations and give two possible molecular con-
formations, A and B (Fig. 1), in analogy with the structures of
17e19.17 The trans orientation of the methyl groups on the pro-
pylene bridge would force one into an axial position and the other
into an equatorial position. Molecules in conformation B could be
envisaged to stack in a helix.
CH3
A
H3C
H3C
CH3
S
S
S
S
S
S
S
S
CH3
CH3
B
CH3
S
S
S
S
S
S
S
S
2.2. Synthesis of donors 13e16
CH3
We have already shown that (ꢁ)-
a-pinene undergoes diaster-
eoselective addition to the trithione 24 to give the thione 25 but,
after conversion to the oxo compound 26, attempted self-coupling
Figure 1. Possible chair conformation of 11 showing the axial and equatorial
dispositions of the methyl groups.

S. Yang et al. / Tetrahedron 66 (2010) 6977e6989
6979
S
S
S
(i)
S
20
S
S
S
S
S
Hg(OAc)2
S
S
/ MeOH
O
S
S
OMes OMes
S
(ii) THF
22 99%
21 45%
S
S
S
S
S
/ (MeO)3P
(MeO)3P
23
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
12 23%
11 75%
Scheme 1.
Figure 2. Two views of the molecular structure of donor 11.
Figure 3. Molecular structure of 12.

6980
S. Yang et al. / Tetrahedron 66 (2010) 6977e6989
in triethyl phosphite gave only tetra(ethylthio)TTF (Scheme 2).9 The
X-ray crystal structure of 25 indicated strain at the quarternary
carbon atom at the fusion with the dithiin ring, and it is probably
this factor in the oxo compound, which facilitates ring opening with
triethyl phosphite. A sensible step would be to make the material
without the methyl group at the strained centre, for which apopi-
nene 27 is required as starting material. Indeed, reaction of apo-
pinene with trithione 2418 by a hetero DielseAlder reaction gave
thione 28 in 67% yield. Conversion of this thione to the oxo com-
pound 29 with mercuric acetate proceeded satisfactorily and the
product was cross-coupled with the unsubstituted thione 23 to give
the donor 13 (Scheme 3). Subsequent crystal structure measure-
ments of the donor in a TCNQ molecular complex19 and in a triio-
dide salt (Fig 10) confirmed the stereochemistry of the addition
reaction of trithione 24 to the less hindered face of apopinene.
However, it is difficult to obtain the starting material (ꢁ)-apopi-
nene from (ꢁ)-mytenal with high enantiopurity, not least because
the enantiomers are interconverted by a shift in position of the
double bond. Thus, our starting material had an ee of only 42%
estimated from its optical rotation.
The rather acute orientation of the bicyclo[3.1.1]heptyl group rel-
ative to the restof the molecule is not ideal for the close packingof the
organosulfur residues. To obtain fusion of the chiral grouping to the
BEDT-TTF system at a carbonecarbon double bond rather than a sin-
gle one, the reaction of the (þ)-nopinone enol acetate 30 with tri-
thione 24 was attempted. It was reasoned that, after cycloaddition to
give intermediate 31, the acetate group might be eliminated by nu-
cleophilicdisplacementbythea-Satomtogivecation32, whichcould
then lose a proton to give the desired product (Scheme 4). Indeed, this
reaction was carried out by refluxing the enol acetate 30 with the
trithione 24, and gave the desired fused thione 33 in 31% yield after
purification. The thione 33 was converted in the usual manner to the
oxo compound 34 in quantitative yield, which was cross-coupled
with the unsubstituted thione 23 by reaction in trimethyl phosphite
at 70 ꢀC for 20 h to give the chiral donor 14 in 63% yield.
CH3
CH3
H3C
H3C
O
OAc
30
S
S
S
S
S
S
S
S
24
S
S
24
CH3
CH3
S
S
CH3
S
S
S
CH3
S
S
S
S
S
H3C
S
H3C
S
S
H3C
H3C
S
S
OAc
CH3
32
31
CH3
25
CH3
CH3
S
S
S
S
S
S
Hg(OAc)2
S
S
CH3
SEt
H3C
S
H3C
O
EtS
S
S
S
S
S
S
S
O
H3C
S
33 31%
34 99%
SEt
EtS
CH3
23 / (MeO)3P
26
CH3
S
S
S
S
S
S
S
Scheme 2.
H3C
S
14 64%
S
S
Scheme 4.
S
CH3
S
24
S
CH3
The molecular structure of donor 14 has been determined by X-ray
crystallography, and one of the two crystallographically unique mol-
ecules is disordered between two orientations.19 The similar shapes of
the two orientations of such a donor could be avoided if chirality were
introduced at the other end of the donor. The most convenient way is
to include two substituents related by a C2 axis, which means there is
onlyone stereoisomerfor the cross-coupledmaterial. We thusdecided
to make two further donors, 15 and 16, by cross-coupling of oxo
compound 34 with (a) thione 21 to give the cross-coupled donor 15 in
S
S
S
S
S
H3C
H3C
28 67%
27
Hg(OAc)2
CH3
S
S
S
O
H3C
75% yield, and (b) the chiral thione derived from
-mannitol 3510 to
give the cross-coupled donor 36 in 31% yield, which was deprotected
with aqueous HCl in THF to give the tetrol 16 (Scheme 5).
D
S
S
S
S
S
/ (EtO)3P
S
29 91%
23
2.3. Charge transfer salts and complexes
CH3
S
S
S
S
S
S
H3C
The c.v. data for donors 11e16 are given in Table 1. All donors
show the usual two oxidation processes expected of BEDT-TTF-like
molecules. The inclusion of seven- rather than six-membered rings
in the donor made almost no difference to the oxidation potentials
of 11 and 12. Donor 13 showed slightly lower oxidation potentials
S
S
13 66%
Scheme 3.

S. Yang et al. / Tetrahedron 66 (2010) 6977e6989
6981
CH3
CH3
(MeO)3P
S
S
S
S
S
S
S
S
S
S
S
S
S
S
H3C
H3C
O
O
S
+
+
S
S
15 75%
21
34
O
O
O
O
CH3
O
O
CH3
O
(MeO)3P
S
S
S
S
S
S
S
S
S
S
S
S
S
H3C
S
H3C
S
S
S
O
35
36 31%
34
H+
OH
CH3
S
OH
OH
S
S
S
S
S
H3C
S
S
OH
16 100%
Scheme 5.
Table 1
Half wave potentials for donors from cyclic voltammetry measurementsa
Donor
E11/2 (V)
E12/2 (V)
2
0.51
0.50
0.51
0.48
0.56
0.59
0.59
0.94
0.96
0.93
0.89
0.97
0.99
0.98
11
12
13
14
15
16
a
Measured relative to Ag/AgCl at a platinum electrode in dichloromethane con-
taining 0.1 M Bu4NPF6 as charge carrier and using a 100 mV sꢁ1 scan.
but in 14 the change in the fusion between the apopinene unit and
the dithiin from a single bond to a double bond led to an increase in
the first two oxidation potentials by ca. 0.08 V. This feature is
retained in the related cross-coupled donors 15 and 16 whose ox-
idation potentials are slightly higher than for 14. We have carried
out some initial electrocrystallisation experiments with donors
11e15 as well as the diffusion of iodine vapour into solutions of
donors. From these we have been able to structurally characterise
two triiodides salts: a 1:1 salt with donor 12 (Figs. 4e6) and
a 3:3þchlorobenzene salt with donor 13 (Figs. 7e10).
Figure 5. Local packing arrangement of cations of 12ꢂD surrounded by four triiodide ions.
The structure of salt 12$I3, prepared from the donor and iodine,
contains two crystallographically unique donor monocations and
two triiodide anions (Figs. 4e6). The two donor cations are packed
together, face to face, with a dithiepine and a dithiin ring opposite
one other. The TTF units lie almost directly opposite each other, and
there are four SeS contacts between these two groups in the range
3.288e3.331 Å. This pair is surrounded by four triodides, two lying
close to and parallel with a pair of donor edges containing sulfur
atoms (twenty IeS contacts in the range 3.678e4.307 Å) and two
further triiodides lying above and below the faces of the donor
cation pair, but in each case nearer to one edge of sulfur atoms (ten
IeS contacts in the range 3.661e4.464 Å). The organosulfur region
of cation 12 is much closer to planar than in the neutral donor. The
organosulfur cores are just slightly bowed, one more so than the
other, such that the angles between the plane containing the four
sulfur atoms of the TTF group and the planes defined by the two
Figure 4. Packing of a pair of cations of 12 in crystal structure of 12$I3.

6982
S. Yang et al. / Tetrahedron 66 (2010) 6977e6989
Figure 6. Crystal packing arrangement in 12$I3 viewed down the a axis, with the c axis horizontal.
Figure 7. Space-filling packing diagram of 133(I3)3$C6H5Cl with the c axis horizontal and a axis vertical.
sets of four sulfur atoms at either side of the molecule are 2.0ꢀ and
2.5ꢀ for one donor cation and 6.2 and 11.4ꢀ for the other cation,
compared to 19.2e19.7ꢀ for the neutral donor. There are notable
differences in the (averaged) bond lengths of the central TTF unit of
the cations of 12 compared to the neutral donor: the central C]C
bond is longer at 1.38 Å (cf. 1.349 Å), but the two CeS bonds are
shorter (1.724 Å cf. 1.759 Å and 1.733 Å cf. 1.763 Å). Furthermore,
these bond lengths are similar to those observed in the BEDT-TTF
monocation in the (BEDT-TTF)HCl2 salt.20 Use of the established
empirical correlation between bond lengths and charge for BEDT-
TTF and its salts21 gives values for the charge on each cation of 12 as
þ1.16(10) and þ1.18(10). The Raman spectrum on this salt shows
signals at 1462 and 1408 cmꢁ1 (compared to 1555, 1507, 1491,
1478 cmꢁ1 in the pure donor), which support the donor’s þ1 oxi-
dation state by comparison with the correlation between Raman
C]C signals and oxidation state for BEDT-TTF.22 Measurement of
resistivity showed the material to be an insulator.23
Electrocrystallisation of donor 13 in chlorobenzene yielded a 3:3
salt with triodide, which included one molecule of chlorobenzene
whose structure was measured by single crystal X-ray diffraction at
the Daresbury Laboratory Synchrotron Radiation Source. The
crystal packing arrangement is presented in Figures 7e10. Within

S. Yang et al. / Tetrahedron 66 (2010) 6977e6989
6983
Figure 8. View of the mutual arrangements of the donor cations and triiodide anions in 133(I3)3$C6H5Cl, viewed down the c axis, with chlorobenzene molecules omitted. Two donor
cation pairs and two isolated donors complete the unit cell.
Figure 9. View of the crystal packing of 133(I3)3$C6H5Cl with donor cations omitted, showing the formation of layers by chlorobenzene molecules and triiodides.

6984
S. Yang et al. / Tetrahedron 66 (2010) 6977e6989
Figure 10. Donor cation pair from the crystal structure of 133(I3)3$C6H5Cl.
Figure 11. The four crystallographically unique molecules in a stack of 15$TCNQ.
the monoclinic unit cell (space group P21) there are two pairs of
donor cations and two isolated donor cations, all of which have
their main axes oriented roughly parallel to the c axis. Four triio-
dides lie between the donor cations and parallel to their axes. This
block extends in the a and b axis directions to form a layer, and
layers are separated by another narrower layer composed of further
triodides and also chlorobenzene molecules, in which the triiodides
lie roughly perpendicular to the other triiodides in the structure.
The organosulfur cores of each donor are close to planar, with rms
deviations for the three independent molecules in the range
0.07e0.11 Å, consistent with a cation structure. The CeS bond
lengths are rather imprecise in the presence of triiodides but, using
bond lengths of the TTF grouping averaged over all three donor
cations, an average charge of þ1.18 was estimated using the em-
pirical correlation approach. Within a pair the two donor cations
are oriented trans with their sulfur atoms opposite each other, and
four S—S separations between their TTF units of 3.365(8)e3.453(8)
Å (Fig. 10). The Raman spectrum is also supportive of the mono-
cation donor structure. Donor 13 also gave some solid black
materials on electrocrystallisation from 1,1,1-trichloroethane and
from THF. Both showed Raman shifts typical of a donor monocation
(1454 and 1402,1453 and 1406 cmꢁ1). Resistivity measurements on
the former24 showed the material to be an insulator. There was
insufficient material for such a measurement on (13)3(I3)3$C6H5Cl.
The bond lengths of the TTF portion of the donor in 15$TCNQ are
typical of an unoxidised donor,26 and this is supported by an
empirical calculation of the charge based on the bond lengths,21
suggesting very little charge transfer from donor to acceptor.
Thus, the donor is not flattened as observed in the structure of the
cation 12þ. The charge on the TCNQ molecule can also be estimated
from its molecular geometry,27 and analysis of the average geom-
etry of the two TCNQ acceptors indicate that the charge is close to
zero. Resistivity measurements on all three TCNQ complexes
showed these materials to be insulators.23
Measurements of the Raman and infra-red spectra also provide
methods for assessing the degree of charge transfer in donors and
acceptors.22,28 The Raman spectra for these complexes each show
a prominent signal at ca. 1600 cmꢁ1 and another one in the range
1434e1450 cmꢁ1
,
which would be consistent with neutral
TCNQ.29,30 In contrast, the infra-red spectra of the TCNQ complexes
of 13e15 show cyanide stretches in the range 2217e2213 cmꢁ1
,
which from the correlation of anionic charge with stretching
frequency corresponds to a net negative charge of ca. 0.35 e.28
However, the range in stretching frequencies between neutral
and monoanionic TCNQ is just 44 cmꢁ1, so other effects from the
crystal environment on the CN stretching frequency may easily
upset the correlation between charge and stretching frequency.
Bernstein has commented on a comparison of the crystallographic
and spectroscopic data for TCNQ complexes in his recent compre-
hensive review30 and elsewhere.27 In summary, the data from the
X-ray and Raman studies support the donor and acceptor being in
their uncharged state in the TCNQ complex.
2.4. TCNQ complexes
Three 1:1 molecular complexes between BEDT-TTF and TCNQ
have been reported, and crystallographic studies have shown them
to have very distinctive packing arrangements.25 Thus, we have
attempted to prepare TCNQ complexes from some of the new
donors reported here, and obtained 1:1 TCNQ complexes from
donors 13, 14 and 15. The solid-state UV/visible spectra for these
compounds all showed a charge transfer band centred in the range
689e701 nm. The X-ray diffraction data were measured and the
structures solved for all three complexes and showed that they
have formed mixed stacks containing alternate donor and acceptor
molecules. The stacks are aligned side by side so that there are lines
of donors or acceptors running perpendicular to the stacking
direction. The measurement of structure of 15$TCNQ was the most
accurate, and is shown in Figure 11. X-ray diffraction data for
14$TCNQ, from a very small crystal, was collected at the new
Diamond Light Source single-crystal diffraction beamline I19 as
part of the commissioning phase in collaboration with the National
Crystallography Service, using procedures that are still under
development. Further details of each structure are provided in the
Supplementary data.
3. Conclusions
Six new chiral donors have been prepared, and studies to
prepare conducting materials initiated, though to date only 1:1
radical cation salts have been prepared. It is notable how the
flexed organosulfur ring system of the donor 12 flattens out when
it is oxidised to its þ1 oxidation state. To form 2:1 salts, which are
more likely to be conducting, there are two approaches. One is to
use ET-derived donors which are only substituted at one end, so
that they can stack head to tail, and such structures have been
observed in achiral cases.31 An alternative approach is to use
mixtures of the chiral donors with an unsubstituted donor, which
can more readily adopt a planar structure even in their unoxidised
state. Despite the reported electronic properties of BEDT-
TTF$TCNQ complexes, it appears that more oxidising acceptors are
needed for reaction with donors 13e15 to obtain electroactive
materials. Further studies on the conversion of these chiral donors
into conducting systems are currently underway. From the

S. Yang et al. / Tetrahedron 66 (2010) 6977e6989
6985
synthetic chemistry point of view, with chiral thiones and oxo
compounds 21e22 and 33e34 in hand, many further donors can
be prepared by cross-coupling reactions.
654, 593, 511, 473, 456, 390; m/z: (ES) 266 [M]þ; found C, 36.14; H,
3.70%, C8H10S5 requires C, 36.06; H, 3.78%; [
a
]
20 þ10.0 (c 0.8, CHCl3).
D
4.1.3. (5S,7S)-5,7-Dimethyl-6,7-dihydro-5H-1,3-dithiolo[4,5-b]-1,3-
dithiepine-2-one 22. Mercuric acetate (4.40 g, 13.8 mmol) was
added to a solution of the thione 21 (2.42 g, 9.08 mmol) in chlo-
roform (100 mL). After stirring for 2 h, the reaction mixture was
filtered and the solid residue washed with chloroform. The com-
bined filtrates were concentrated in vacuo and the residue purified
by flash chromatography (cyclohexane/DCM 4:1) to yield the oxo
compound 22 as a reddish oil (2.25 g, 99.0%); Rf (cyclohexane/DCM
4:1) 0.33; dH (400 MHz, CDCl3) 3.28 (2H, m, 5-,7-H), 2.26 (2H, t, J
5.5 Hz, 6-H2), 1.32 (6H, d, J 7.1 Hz, 2ꢃCH3); dC (100.6 MHz, CDCl3)
189.9 (C]O), 127.4 (3a-,8a-C), 47.8 (6-C), 37.9 (5-,7-C), 20.3
(2ꢃCH3); nmax (ATR): 2961, 2922, 2868, 1667, 1615, 1487, 1446, 1418,
1380, 1243, 1192, 1106, 1076, 1034, 998, 883, 751, 551, 470; m/z: (EI)
250 [M]þ; found C, 38.30; H, 3.93%, C8H10OS4 requires C, 38.37; H,
4. Experimental
4.1. General
NMR spectra were measured on a Jeol ECLIPSE 400 spectrometer
at 400 MHz for 1H and at 100.6 MHz for 13C using CDCl3 as solvent
and tetramethylsilane (TMS) as standard unless otherwise stated,
and measured in parts per million downfield from TMS. IR spectra
were recorded on PerkineElmer Spectrum 100 FT-IR Spectrometer,
and are reported in cmꢁ1. Raman measurements were made on
a Foster and Freeman Raman spectrometer, Foram 685-2, with
excitation at 685 nm and are reported in cmꢁ1. Solid-state UV/vis-
ible spectra were measured using a JASCO V-670. Optical rotation
data were measured on a PerkineElmer 241 polarimeter. Mass
spectra were recorded at the EPSRC Mass Spectrometry Centre at
the University of Swansea. Chemical analysis data were obtained
from Mr Stephen Boyer, London Metropolitan University. X-ray
diffraction datasets were measured by the EPSRC National Crys-
tallography Service (NCS) at Southampton University, except for
(13)3(I3)3$C6H5Cl, which was investigated at Daresbury Laboratory
Synchrotron Radiation Source and 14$TCNQ, which was in-
vestigated at Diamond Light Source, both of these through the
synchrotron component of the NCS run from Newcastle University.
Flash chromatography was performed on 40e63 silica gel (Merck).
4.02%; [
a]
20 ꢁ50.7 (c 1.70, CHCl3).
D
4.1.4. Bis((2S,4S)-pentane-2,4-dithio)tetrathiafulvalene 11. A mix-
ture of oxo compound 22 (451 mg, 1.80 mmol) and freshly distilled
trimethyl phosphite (20 mL) was heated to reflux for 24 h. The re-
action mixture was cooled to room temperature, and the yellow
solid collected by filtration, washed with ethyl acetate and dried in
vacuo to give donor 11 (318 mg, 75.3%); mp 195e197 ꢀC; Rf (cyclo-
hexane/DCM 4:1) 0.22; dH (400 MHz, CDCl3) 3.16 (4H, m, 2-,20-,4-,40-
H), 2.24 (4H, t, J 5.4 Hz, 3-,30-H2), 1.30 (12H, d, J 7.1 Hz, 4ꢃCH3); dC
(100.6 MHz, CDCl3) 127.4 (4ꢃsp2-C(dithiepine)), 112.8 (2ꢃsp2-C
(central)), 48.7 (3-,30-C), 37.9 (2-,20-,4-,40-C), 20.5 (4ꢃCH3); nmax
(ATR): 2958, 1441, 1375, 1241, 1189, 1104, 1076, 1034, 993, 881, 768,
653, 590, 530, 488, 455, 388; m/z: (EI) 468 [M]þ; HRMS (EI) found:
467.9320, C16H20S8 requires: 467.9325; found C, 41.03; H, 4.24%,
4.1.1. (2R,4R)-Pentanediyl-bis(methanesulfonate)32. Triethylamine
(7.50 mL, 53.8 mmol) was added to a solution of (2R,4R)-(ꢁ)-pen-
tanediol (2.00 g, 19.2 mmol) in dichloromethane (70 mL). The
resulting mixture was cooled to 0 ꢀC, and methanesulfonyl chloride
(4.00 mL, 51.7 mmol) was added dropwise over 10 min. The mix-
ture was stirred at 0 ꢀC for 2 h and then poured into 40 mL of cold
1 N HCl. The aqueous layer was extracted with dichloromethane
(2ꢃ40 mL) and the combined organic phases were washed with
saturated NaHCO3 solution, dried with MgSO4, filtered and con-
centrated. The bis(methanesulfonate) was obtained in quantitative
yield (5.00 g, 100%) as a colourless oil and used without further
purification. dH (400 MHz, CDCl3) 4.93 (2H, m, 2-,4-H), 3.06 (6H, s,
2ꢃCH3SO2), 1.89 (2H, dd, J 5.5, 7.4 Hz, 3-H2), 1.47 (6H, d, J 6.0 Hz, 1,5-
H3); dC (100.6 MHz, CDCl3) 75.5 (2-,4-C), 43.4 (3-C), 38.7
(2ꢃCH3SO2), 21.7 (2ꢃCH3).
C16H20S8 requires C, 40.99; H, 4.30%; [
a]
20 ꢁ153.0 (c 0.2, CHCl3).
D
4.1.5. (Ethylenedithio)((2S,4S)-pentane-2,4-dithio)tetrathiafulvalene
12. A mixture of oxo compound 22 (0.69 g, 2.76 mmol), unsub-
stituted thione 23 (2.00 g, 8.90 mmol) and freshly distilled trimethyl
phosphite (50 mL) was heated to 70 ꢀC for 30 h. The reaction mix-
ture was cooled to room temperature then filtered and washed with
chloroform. The solvent was evaporated to dryness and the residue
purified by chromatography (cyclohexane/ethyl acetate 4:1) to give
donor 12 (265 mg, 22.5%); mp 131e133 ꢀC; Rf (cyclohexane/ethyl
acetate 8:1) 0.29; dH (400 MHz, CDCl3) 3.22 (4H, s, CH2CH2), 3.12 (2H,
m, 2-,4-H), 2.22 (2H, t, J 5.4 Hz, 3-H2),1.26 (6H, d, J 7.0 Hz, 2ꢃCH3); dC
(100.6 MHz, CDCl3) 127.9 (2ꢃsp2-C(dithiepine)), 115.4 (2ꢃsp2-C
(dithiin)),113.8 and 109.1 (2ꢃsp2C(central)), 48.7 (3-C), 37.5 (2-,4-C),
30.2 (CH2CH2), 20.5 (2ꢃCH3); nmax (ATR): 2954, 2915, 2866, 1442,
1373,1288, 1241,1192, 1125,1073,1031, 996, 902, 890, 849, 770, 514,
490, 442, 406, 389; m/z: (EI) 426 [M]þ; found C, 36.68; H, 3.23%,
4.1.2. (5S,7S)-5,7-Dimethyl-6,7-dihydro-5H-1,3-dithiolo[4,5-b]-1,3-
dithiepine-2-thione 21. A solution of dithiolate 20 was generated by
reaction of 4,5-bis(benzoylthio)-1,3-dithiole-2-thione (7.80 g,
19.2 mmol) with 2 equiv of sodium methoxide in dry methanol
(300 mL) under a nitrogen atmosphere and then treated with
(2R,4R)-pentanediyl-bis(methanesulfonate) (5.00 g, 19.2 mmol) at
room temperature. The deep purple solution turned orange-red
over several minutes, and the mixture was stirred at room tem-
perature overnight. The solvent was removed in vacuo at room
temperature, and replaced with dry THF (300 mL), and the result-
ing solution heated to reflux for 24 h. The mixture was filtered and
the solids washed with further THF, and the combined filtrates
evaporated. The residue was partitioned between dichloromethane
and water, the organic layer separated, and washed again with
water and dried with magnesium sulfate. Flash chromatography
(cyclohexane/DCM 4:1) gave the product 21 (2.48 g, 44.9%) as
a yellow solid; mp 65e67 ꢀC; Rf (cyclohexane/DCM 4:1) 0.36; dH
(400 MHz, CDCl3) 3.35 (2H, m, 5-,7-H), 2.32 (2H, t, J 5.5 Hz, 6-H2),
1.35 (6H, d, J 7.1 Hz, 2ꢃCH3); dC (100.6 MHz, CDCl3) 211.6 (C]S),
136.9 (3a-,8a-C), 48.4 (6-C), 38.2 (5-,7-C), 20.5 (2ꢃCH3); nmax (ATR):
2957, 2918, 1443, 1412, 1380, 1239, 1050, 1023, 994, 881, 852, 779,
C13H14S8 requires C, 36.59; H, 3.31%; [
a]
20 ꢁ80.5 (c 0.2, CHCl3).
D
4.1.6. (1S,5R)-6,6-Dimethylbicyclo[3.1.1]hept-2-ene 2733a,b. A slurry
of (ꢁ)-myrtenal (8.00 g, 53.0 mmol) and freshly made palladium
hydroxide on barium sulfate (1.00 g) was heated slightly above
140 ꢀC with magnetic stirring for 1.5 h. A DeaneStark trap col-
lected 6 mL (83%) of the desired apopinene. dH (400 MHz, CDCl3)
6.08 (1H, m, 2-H), 5.48 (1H, m, 3-H), 2.30 (1H, m, 7-Ha), 2.20 (2H,
m, 4-H2), 2.04 (2H, m, 1-,5-H), 1.20 (3H, s, CH3), 1.13 (1H, d, J 8.2 Hz,
7-Hb), 0.82 (3H, s, CH3); dC (100.6 MHz, CDCl3) 136.5 and 124.1 (2-
,3-C), 41.9 and 41.2 (1-,5-C), 38.0 (6-C), 32.5 and 32.0 (4-,7-C), 26.4
and 21.3 (2ꢃCH3); [
a]
20 ꢁ19.4 (neat). Estimated ee 42%, from value
D
of [
a]
20ꢁ45.1 for material with ee of 98%.33c
D
4.1.7. (4aR,5R,7R,8aS)-6,6-Dimethyl-4a,5,6,7,8,8a-hexahydro-5,7-
methano-benzo[b]1,3-dithiolo[4,5-e]1,4-dithiin-2-thione 28. A sus-
pension of trithione 24 (4.00 g, 20.0 mmol) in a mixture of

6986
S. Yang et al. / Tetrahedron 66 (2010) 6977e6989
apopinene 27 (1.48 g, 12.0 mmol) and toluene (120 mL) was
refluxed for 24 h. The reaction mixture was filtered hot and the
solid residue was washed with chloroform. The combined filtrates
were evaporated and the residue purified by column chromatog-
raphy (cyclohexane/chloroform 4:1) to yield the thione 28 (2.58 g,
66.8%) as a yellow solid; mp 60e62 ꢀC; Rf (cyclohexane/chloroform
4:1) 0.30; dH (400 MHz, CDCl3) 4.05 (1H, d, J 8.2 Hz, 4a-H), 3.64 (1H,
m, 8a-H), 2.64 (1H, m, 8-Ha), 2.44 (1H, m, 10-Ha), 2.15 (1H, s, 7-H),
reduced pressure. The residue was diluted with diethyl ether
(100 mL) and washed with water. After drying over magnesium
sulfate, ether was removed to yield the nopinone enol acetate as
a colourless oil (3.18 g, 97.5%). dH (400 MHz, CDCl3) 5.15 (1H, m,
3-H), 2.46 (1H, m, 7-Ha), 2.28 (1H, d, J 16.0 Hz, 4-Ha), 2.20 (1H, dt, J
16.0 Hz, 2.5 Hz, 4-Hb), 2.09 (2H, m, 1-,5-H2), 2.08 (3H, s, COCH3),
1.42 (1H, d, J 8.7 Hz, 7-Hb), 1.28 (3H, s, 6-CH3), 0.93 (3H, s, 6-CH3); dC
(100.6 MHz, CDCl3) 169.1 (C]O), 156.1 (2-C), 106.3 (3-C), 46.0 (1-C),
40.4 (5-C), 38.9 (6-C), 31.5 (7-C), 28.0 (4-C), 25.8 (6-CH3), 21.0
(6-CH3), 20.9 (CH3CO).
2.14 (1H, s, 5-H), 1.93 (2H, d
CH3), 0.98 (3H, s, -CH3); dC (100.6 MHz, CDCl3) 210.6 (C]S), 138.4
and 138.1 (3a-,9a-C), 56.8 (4a-C), 46.3 (5-C), 45.3 (8a-C), 41.3 (6-C),
39.1 (7-C), 33.4 (10-C), 26.2 (8-C), 26.0 ( -CH3), 20.7 ( -CH3); nmax
*
, J 12.6 Hz, 8-Hb, 10-Hb), 1.36 (3H, s, a-
b
a
b
4.1.11. (5R,7R)-6,6-Dimethyl-5,6,7,8-tetrahydro-5,7-methano-benzo
[b]1,3-dithiolo[4,5-e]1,4-dithiin-2-thione 33. Enol acetate 30 (3.18 g,
17.6 mmol) and trithione 24 (4.50 g, 22.9 mmol) were refluxed
together in toluene (120 mL) for 44 h. The reaction mixture was
filtered and the solid residue washed with chloroform. The com-
bined filtrates were concentrated in vacuo and the residue was
purified by flash chromatography (cyclohexane) to yield thione 33
as an orange oil (1.75 g, 31.3%); Rf (cyclohexane) 0.14; dH (400 MHz,
CDCl3) 2.60 (1H, dd, J 17.6, 2.8 Hz, 8-Ha), 2.51 (1H, m, 10-Ha), 2.45
(1H, dd, J 17.6, 2.8 Hz, 8-Hb), 2.38 (1H, t, J 5.5 Hz, 5-H), 2.20 (1H, m,
7-H), 1.35 (1H, d, J 9.6 Hz, 10-Hb), 1.30 (3H, s, 6-CH3), 0.77 (3H, s,
6-CH3); dC (100.6 MHz, CDCl3) 214.0 (C]S),138.9 (4a-C),127.9,127.5
and 124.6 (3a-, 4a-, 8a-C), 49.5 (5-C), 40.5 (7-C), 40.4 (6-C), 36.9
(8-C), 32.1 (10-C), 25.4 (6-CH3), 20.8 (6-CH3); nmax (ATR): 2970,
2931, 2867, 1487, 1465, 1443, 1383, 1366, 1113, 1058, 1012, 899, 755,
(KBr): 1466, 1447, 1384, 1369, 1314, 1275, 1244, 1201, 1059, 1032,
1025, 926, 912, 888, 782, 511; m/z: (EI) 319 [M]þ; HRMS (EI) found:
317.9693, C12H14S5 requires: 317.9694; found C, 45.33; H, 4.59%,
C12H14S5 requires C, 45.24; H, 4.43%; [
this is a scalemic mixture. Denotes further small splittings.
a
]
20 þ8.3 (c 0.2, CHCl3). N.B.:
D
*
4.1.8. (4aR,5R,7R,8aS)-6,6-Dimethyl-4a,5,6,7,8,8a-hexahydro-5,7-
methano-benzo[b]1,3-dithiolo[4,5-e]1,4-dithiin-2-one 29. Mercuric
acetate (4.30 g, 13.5 mmol) was added to a solution of the thione
28 (2.86 g, 8.97 mmol) in chloroform (85 mL). After stirring for
2 h, the reaction mixture was filtered and the solid residue
washed with chloroform. The combined filtrates were concen-
trated in vacuo and the residue was purified by flash chroma-
tography (cyclohexane/chloroform 4:1) to yield the oxo
compound 29 as a yellow solid (2.48 g, 91.4%); mp 100e102 ꢀC; Rf
(cyclohexane/chloroform 4:1) 0.26; dH (400 MHz, CDCl3) 4.03
(1H, d, J 8.0 Hz, 4a-H), 3.61 (1H, m, 8a-H), 2.54 (1H, m, 8-Ha), 2.37
(1H, m, 10-Ha), 2.07 (2H, m, 5-,7-H), 1.84 (2H, m, 8-Hb, 10-Hb),
617, 506, 476, 451, 386; m/z: (EI) 316 [M]þ; found C, 45.62; H, 3.70%,
20
C12H12S5 requires C, 45.53; H, 3.82%; [
a
]
ꢁ61.4 (c 0.4, CHCl3).
D
4.1.12. (5R,7R)-6,6-Dimethyl-5,6,7,8-tetrahydro-5,7-methano-benzo
[b]1,3-dithiolo[4,5-e]1,4-dithiin-2-one 34. Mercuric acetate (2.26 g,
7.09 mmol) was added to a solution of the thione 33 (1.50 g,
4.74 mmol) in chloroform (50 mL). The reaction mixture was stirred
overnight, filtered and the solid residue washed with chloroform. The
combined filtrates were concentrated in vacuo and the residue was
purified by flash chromatography (cyclohexane/ethyl acetate 20:1) to
yield the oxo compound 34 as a pale yellow solid (1.40 g, 98.5%); mp
92e94 ꢀC; Rf (cyclohexane/ethyl acetate 20:1) 0.55; dH (400 MHz,
CDCl3) 2.62 (1H, dd, J 17.2, 2.8 Hz, 8-Ha), 2.52 (1H, m,10-Ha), 2.46 (1H,
dd, J17.2, 2.5 Hz,8-Hb),2.40(1H, t, J5.5 Hz,5-H), 2.21(1H, m,7-H),1.38
(1H, d, J 9.2 Hz, 10-Hb), 1.31 (3H, s, 6-CH3), 0.74 (3H, s, 6-CH3); dC
(100.6 MHz, CDCl3) 192.5 (C]O),139.1 (4a-C),124.5 (8a-C), 118.1 (3a-
C),117.5(9a-C), 49.5 (5-C), 40.6 (7-C), 40.5 (6-C), 37.0(8-C), 32.1 (10-C),
25.4 (6-CH3), 20.7 (6-CH3); nmax (ATR): 2970, 2927, 2903, 1744, 1674,
1607, 1592, 1421, 1363, 1115, 1094, 1018, 963, 899, 875, 748, 619, 542,
470, 460, 451; m/z: (EI) 300 [M]þ; found C, 47.96; H, 4.06%, C12H12OS4
1.30 (3H, s,
190.3 (C]O), 129.0 and 128.9 (3a-,9a-C), 57.4 (4a-C), 46.3 (5-C),
45.7 (8a-C), 41.3 (6-C), 39.1 (7-C), 33.5 (10-C), 26.1 (8-C), 26.0 (
a-CH3), 0.92 (3H, s, b-CH3); dC (100.6 MHz, CDCl3)
a
-
CH3), 20.6 (b-CH3); nmax (KBr): 2900, 1710, 1464, 1370, 1246, 1164,
1064, 1021, 926, 888, 782; m/z: (EI) 302 [M]þ; HRMS (EI) found:
301.9924, C12H14OS4 requires: 301.9922; found C, 47.77; H, 4.57%,
20
C12H14OS4 requires C, 47.65; H, 4.66%; [
N.B.: this is a scalemic mixture.
a
]
þ7.2 (c 1.00, CHCl3).
D
4.1.9. (Ethylenedithio)((1R,2R,3S,5R)-6,6-dimethyl-bicyclo[3.1.1]hep-
tane-2,3-dithio)tetrathiafulvalene 13. A mixture of oxo compound
29 (163 mg, 0.450 mmol), unsubstituted thione 23 (330 mg,
1.47 mmol) and freshly distilled trimethyl phosphite (10 mL) was
heated to 70 ꢀC for 22 h. The reaction mixture was cooled to room
temperature, then filtered and washed with chloroform. The sol-
vent was evaporated to dryness, and the residue purified by flash
chromatography (cyclohexane/chloroform 4:1) to give donor 13
(170 mg, 66.0%); mp 156e158 ꢀC (dec); Rf (cyclohexane/chloroform
4:1) 0.30; dH (400 MHz, CDCl3) 3.94 (1H, d, J 8.4 Hz, 2-H), 3.45 (1H,
m, 3-H), 3.30 (4H, m, CH2CH2), 2.54 (1H, m, 4-Ha), 2.33 (1H, m, 7-
Ha), 1.98 (1H, s, 5-H), 1.97 (1H, s, 1-H), 1.79 (2H, m, 4-Hb, 7-Hb), 1.30
requires C, 47.96; H, 4.03%; [
a
]
20 ꢁ54.2 (c 0.8, CHCl3).
D
4.1.13. (Ethylenedithio)((1R,5R)-6,6-dimethyl-bicyclo[3.1.1]heptene-
2,3-dithio)- tetrathiafulvalene 14. A mixture of oxo compound 34
(1.44 g, 4.79 mmol), unsubstituted thione 23 (2.70 g, 12.0 mmol)
and freshly distilled trimethyl phosphite (70 mL) was heated to
70 ꢀC for 20 h. The reaction mixture was cooled to room tempera-
ture, then filtered and washed with chloroform. The solvent was
evaporated to dryness and the residue purified by flash chroma-
tography (cyclohexane/DCM 4:1) to give donor 14 as a yellow
powder (1.46 g, 63.9%); mp 205e207 ꢀC (dec); Rf (cyclohexane/
DCM 4:1) 0.34; dH (400 MHz, CDCl3) 3.22 (4H, m, CH2CH2), 2.48 (1H,
dd, J 17.2, 2.8 Hz, 4-Ha), 2.43 (1H, m, 7-Ha), 2.35 (1H, dd, J 17.2,
2.6 Hz, 4-Hb), 2.26 (1H, t, J 5.6 Hz,1-H), 2.12 (1H, m, 5-H),1.30 (1H, d,
(3H, s,
a-CH3), 0.93 (3H, s, b-CH3); dC (100.6 MHz, CDCl3) 129.0,
128.9, 128.8, 113.7, 113.5 (6ꢃsp2-C), 55.9 (2-C), 46.3 (1-C), 44.8 (3-C),
41.0 (6-C), 39.3 (5-C), 33.5 (7-C), 26.1 (4-C), 26.0 and 20.6 (2ꢃeCH3);
nmax (KBr): 2916, 1636, 1470, 1450, 1410, 1385, 1368, 1319, 1283,
1192, 1136, 1048, 995, 924, 910, 882, 770; m/z: (EI) 478 [M]þ; HRMS
(EI) found: 477.9165, C17H18S8 requires: 477.9169; found C, 42.48; H,
20
3.70%, C17H18S8 requires C, 42.64; H, 3.79%; [
CHCl3). N.B.: this is a scalemic mixture.
a]
þ17.6 (c 0.44,
D
4.1.10. Enol acetate of 1R-(þ)-nopinone 3034. (þ)-(1R)-Nopinone
(2.50 g, 18.1 mmol) and p-toluenesulfonic acid (0.50 g, 2.60 mmol)
in isopropenyl acetate (50.0 mL, 454 mmol) were heated to reflux
and the acetone formed in the reaction fractionally distilled from
the system through a 12-inch column packed with glass helices.
After 5 h, the remaining isopropenyl acetate was removed under
J 9.4 Hz, 17-Hb),1.24 (3H, s, 6-CH3), 0.74 (3H, s, 6-CH3); dC
(100.6 MHz, CDCl3) 139.1 (2-C), 124.9 (3-C), 119.9, 119.5, 117.3, 113.7,
112.9 (6ꢃsp2-C), 49.2 (1-C), 40.6 (5-C), 40.5 (6-C), 36.8 (4-C), 32.1
(7-C), 30.1 (CH2CH2), 25.5 (6-CH3), 20.8 (6-CH3); nmax (ATR): 2973,
2908, 1601, 1465, 1445, 1423, 1382, 1365, 1263, 1111, 1091, 1014, 909,
896, 766, 617, 508, 445, 397; m/z: (EI) 476 [M]þ; found C, 42.73; H,

S. Yang et al. / Tetrahedron 66 (2010) 6977e6989
6987
20
3.33%, C17H16S8 requires C, 42.82; H, 3.38%; [
CHCl3).
a
]
ꢁ53.5 (c 0.4,
(EI) 676 [M]þ; found C, 42.35; H, 3.95%, C21H24O4S8 requires C,
D
20
42.25; H, 4.05%; [
a
]
D
þ81.2 (c 0.24, THF).
4.1.14. ((2S,4S)-Pentane-2,4-dithio)((10R,50R)-60,60-dimethyl-bicyclo
[3.1.1]heptene-20,30-dithio)tetrathiafulvalene 15. A mixture of oxo
compound 34 (0.80 g, 2.66 mmol), thione 21 (1.80 g, 6.75 mmol)
and freshly distilled trimethyl phosphite (70 mL) was heated to
70 ꢀC for 26 h. The reaction mixture was concentrated and the
components separated by flash chromatography (cyclohexane/
DCM 4:1) to give donor 15 as a yellow powder (1.04 g, 75.3%); mp
161e163 ꢀC (dec); Rf (cyclohexane/DCM 4:1) 0.35; dH (400 MHz,
CDCl3) 3.17 (2H, m, 2-,4-H), 2.52 (1H, dd, J 17.2, 2.8 Hz, 40-Ha),
2.46 (1H, m, 7-Ha), 2.39 (1H, dd, J 17.2, 2.6 Hz, 4-Hb), 2.30 (1H, t, J
5.6 Hz, 1-H), 2.25 (2H, t, J 5.4 Hz, 3-H2), 2.12 (1H, m, 5-H), 1.34
(1H, d, J 9.5 Hz, 7-Hb), 1.30 (6H, dd, J 7.1, 4.8 Hz, 2-,4-CH3), 1.28
(3H, s, 60-CH3), 0.79 (3H, s, 60-CH3); dC (100.6 MHz, CDCl3) 139.1
(20-C), 127.8, 127.7 (2ꢃsp2C(dithiepine)), 124.8 (30-C), 119.8, 119.4,
116.7, 114.7 (4ꢃsp2-C), 49.2 (10-C), 48.7 (3-C), 40.6 (50-C), 40.5 (60-
C), 37.7 (br), 37.6 (br, 2-,4-C), 36.8 (40-C), 32.1 (70-C), 25.5 (60-CH3),
20.8 (60-CH3), 20.6, 20.3 (2-,4-CH3); nmax (ATR): 2970, 2955, 2921,
1601, 1464, 1442, 1428, 1416, 1378, 1364, 1237, 1113, 1074, 1014,
4.2. Electrocrystallisations
4.2.1. With donor 13.
(a) Electrocrystallisation of donor 13 (10 mg) in a solution of tet-
rabutylammonium triiodide (57 mg) in chlorobenzene (20 mL)
at room temperature, using a constant current of 0.1 mA over 3
weeks, afforded black crystals of (13)3(I3)3$C6H5Cl. Raman:
1443, 1426, 1395.
(b) Electrocrystallisation of donor 13 (10 mg) in a solution of
tetrabutylammonium triiodide (120 mg) in 1,1,1-trichloro-
ethane (40 mL) at room temperature, using a constant current
of 1.0 mA over 2 weeks, afforded black needle crystals of
(13)2(I3)2$Cl3CCH3. Raman: 1402 and 1453 (Raman for donor
13: 1548, 1510, 1488). A similar experiment in THF, conducted
at 3.0 mA over 15 days gave a black material exhibiting Raman
signals at 1406 and 1453, indicating a 1:1 donor cation/tri-
odide ratio.
997, 897, 769, 651, 618, 597, 513; m/z: (EI) 518 [M]þ; found C,
20
46.30; H, 4.17%, C20H22S8 requires C, 46.29; H, 4.27%; [
a
]
ꢁ94.3
D
(c 0.3, CHCl3).
4.3. Reaction of 12 with iodine
4.1.15. (2R,3R,4R,5R-)Bis(O,O-isopropylidene)-1,2,5,6-tetrahydrox-
yhexan-3,4-dithio ((10R,50R)-60,60-dimethylbicyclo[3.1.1]heptene-20,30-di-
thio)tetrathiafulvalene 37. A mixture of oxo compound 34 (0.624 g,
2.08 mmol), thione 35 (0.528 g, 1.24 mmol) and freshly distilled
trimethyl phosphite (35 mL) was heated to 70 ꢀC for 48 h. The
reaction mixture was concentrated and the components separated
by flash chromatography (cyclohexane/ethyl acetate 20:1) to give
donor 36 as an orange powder (0.258 g, 30.6%); mp 95e97 ꢀC
(dec); Rf (cyclohexane/ethyl acetate 20:1) 0.21; dH (400 MHz,
CDCl3) 4.36 (2H, m, 2-,5-H), 4.13 (2H, dd, J 8.5, 6.3 Hz, 1-,6-Ha),
3.99 (2H, m, 1-,6-Hb), 3.66 (2H, m, 3-,4-H), 2.50 (1H, dd, J 17.2,
2.9 Hz, 40-Ha), 2.44 (1H, m, 70-Ha), 2.36 (1H, dd, J 17.2, 2.4 Hz, 40-
Hb), 2.28 (1H, t, J 5.5 Hz, 10-H), 2.14 (1H, m, 50-H), 1.39 (6H, s,
2ꢃCH3), 1.32 (d, partially obscured, 7-Hb), 1.30 (6H, s, 2ꢃCH3), 1.26
(3H, s, 60-CH3), 0.76 (3H, s, 60-CH3); dC (100.6 MHz, CDCl3) 139.1
(20-C), 124.7 (30-C), 119.8, 119.3, 117.8, 111.5, 109.9, 109.3 (6ꢃsp2-C),
110.2 (2ꢃeO2C), 76.0, 75.8 (2-,5-C), 67.9, 67.8 (1-,6-C), 49.1 (10-C),
44.9, 44.7 (3-,4-C), 40.5 (50-C), 40.4 (60-C), 36.7 (40-C), 32.0 (70-C),
27.0 (2ꢃCH3), 25.4 (60-CH3), 25.3 (2ꢃCH3), 20.7 (60-CH3); nmax
(ATR): 2983, 2933, 1453, 1380, 1369, 1244, 1210, 1146, 1061, 1020,
A solution of donor 12 (10 mg) in 1,1,2-trichloroethane (5 mL)
was placed in a tank containing iodine vapour and left for 3 days,
and gave black crystals of the 12$I3 salt. nmax (ATR): 2955, 2912,
2854, 2823, 1409, 1322, 1235, 1168, 1016, 998, 882, 487, 476, 457;
Raman: 1462, 1408, 572 (Raman for pure 12: 1555, 1507, 1491, 1478,
493).
4.4. Preparation of TCNQ complexes
4.4.1. 13$TCNQ. To
a
hot solution (90 ꢀC) of TCNQ (5 mg,
0.024 mmol) in 1,1,2-trichloroethane (3 mL) was added a hot so-
lution (90 ꢀC) of donor 13 (11 mg, 0.023 mmol) in 1,1,2-trichloro-
ethane (2 mL), and the mixture was heated at 90 ꢀC for 2 h. The
solvent was left to evaporate slowly to precipitate 13$TCNQ as black
crystals, nmax (ATR): 2914, 2214 (CN), 1668, 1533, 1506, 1450, 921,
909, 885, 837, 772, 495, 472, 398; Raman 1597, 1533, 1434, 1187
(Raman of pure 13: 1549, 1510, 1488); lmax (solid state): 213, 294,
350, 650, 689.
969, 901, 834, 770, 617, 511; m/z: (EI) 676 [M]þ; found C, 47.84; H,
4.4.2. 14$TCNQ. To a
hot solution (90 ꢀC) of TCNQ (5 mg,
20
4.70%, C27H32O4S8 requires C, 47.90; H, 4.76%; [
CHCl3).
a]
þ4.5 (c 0.2,
0.023 mmol) in 1,1,2-trichloroethane (3 mL) was added a hot so-
lution (90 ꢀC) of donor 14 (11 mg, 0.023 mmol) in 1,1,2-trichloro-
ethane (2 mL), and the mixture was heated at 90 ꢀC for 2 h. 1,1,2-
Trichloroethane was removed in vacuo and some acetonitrile was
added to dissolve all solid material and then evaporated slowly to
precipitate 14$TCNQ as black microcrystals, found C, 51.1; H, 3.0; N,
8.1%, C29H20N4S8 requires C, 51.2; H, 3.0; N, 8.2%; nmax (ATR): 2217
(CN), 1536, 1516, 1412, 903, 840, 770, 473; Raman: 1600, 1546
(weak), 1501 (weak), 1450, 1190, 989 (Raman of pure 14: 1549,
1498); lmax (solid state):212, 304, 405, 522, 701.
D
4.1.16. ((2R,3R,4R,5R)-1,2,5,6-Tetrahydroxy-3,4-dithio)((10R,50R)-
60,60-dimethyl-bicyclo[3.1.1]heptene-20,30-dithio)tetrathiafulvalene
16. Diketal 36 (0.120 g, 0.180 mmol) was stirred with a mixture of
aq HCl (4 M, 8 mL) and THF (20 mL) under nitrogen for 12 h.
Evaporation and drying in vacuo gave the donor 16 (0.105 g, 100%)
as a buff powder, mp 140e142 ꢀC; dH (400 MHz, DMSO-d6) 5.20
(2ꢃOH), 4.66 (2ꢃOH), 3.89 (2H, m, 2-,5-H), 3.65 (2H, m, 1-,6-Ha),
3.58 (2H, m, 1-,6-Hb), 3.51 (2H, m, 3-,4-H), 2.61 (1H, dd, J 17.2,
2.8 Hz, 40-Ha), 2.51 (1H, m, partially obscured, 70-Ha), 2.35 (2H, m,
10-,40-Hb), 2.16 (1H, m, 50-H), 1.27 (3H, s, 60-CH3), 1.24 (1H, d, par-
tially obscured, 70-Hb), 0.73 (3H, s, 60-CH3); dC (100.6 MHz, DMSO-
d6) 138.4 (20-C), 124.9 (30-C), 119.6, 119.2, 115.3, 112.5, 110.7, 109.9,
(6ꢃsp2-C), 72.0, 71.6 (2-,5-C), 63.2 (1,6-C), 48.6 (10-C), 42.8, 42.6
(3-,4-C), 36.3 (40-C), 31.5 (70-C), 25.0 (60-CH3), 20.5 (60-CH3),
Expected peaks 40.5 (50-C), 40.4 (60-C) are obscured by the peak due
to DMSO-d6; nmax (ATR): 3264, 2983, 2930, 1451, 1425, 1381, 1369,
1212, 1148, 1101, 1063, 1018, 924, 900, 876, 834, 769, 617, 512; m/z:
4.4.3. 15$TCNQ. To a hot solution (65 ꢀC) of donor 15 (10 mg,
0.019 mmol) in a mixture of acetonitrile (5 mL) and chloroform
(1.5 mL) was added
a
hot solution (65 ꢀC) of TCNQ (5 mg,
0.024 mmol) in acetonitrile (3 mL), and the mixture was heated at
65 ꢀC for 2 h. The solvent evaporated slowly to produce 15$TCNQ as
a black crystalline solid, nmax (ATR): 2974, 2938, 2213 (CN), 1536,
1497, 1442, 1378, 1352,1040, 877, 838, 770, 472; Raman: 1600, 1490,
1443 (Raman of pure 15: 1552, 1514, 1488); lmax (solid state): 213,
301, 335, 399, 479 sh, 693.

6988
S. Yang et al. / Tetrahedron 66 (2010) 6977e6989
4.5. X-ray crystallography
from support from ESF COST action D35. We thank Mr. Brian O’Neill
for construction of constant current sources.
Data were collected with Mo Ka radiation at 100e150 K, except
for (13)3(I3)3$C6H5Cl and 14$TCNQ, for which the synchrotron X-ray
wavelengths were 0.6710 and 0.6889 Å, respectively. The structures
were solved with SHELXS-97 and refined with SHELXL-97.35
Supplementary data
Supplementary data associated with this article can be found in
online version at doi:10.1016/j.tet.2010.06.034. These data include
MOL files and InChIKeys of the most important compounds
described in this article.
Molecular illustrations are made with ORTEP-336 and Mercury37
.
Data have been deposited at the Cambridge Crystallographic Data
Centre,12 Union Road, Cambridge, CB2 1EZ with reference numbers
CCDC 749271e749278.
Crystal data for 11: C16H20S5, Mr¼468.80, orthorhombic,
a¼7.7282(3), b¼12.4310(5), c¼21.2863(8) Å, V¼2044.96(14) Å3,
References and notes
Z¼4, P212121, Dc¼1.52 g cmꢁ3
,
m
¼0.087 mmꢁ1
T¼100 K, 5095
,
1. Herranz, M.; Sanchez, L.; Martin, N. Phosphorous Sulfur Silicon Relat. Elem. 2005,
180, 1133; Bendikov, M.; Wudl, F.; Perepichka, D. F. Chem. Rev. 2004, 104, 4891;
Day, P. Compt. Rend. Chim. 2003, 6, 301; Mori, H. Opt. Sci. Eng. 2008, 133, 263;
Singleton, J. J. Solid State Chem. 2002, 168, 675.
2. Krstic, V.; Roth, S.; Burghard, M.; Kern, K.; Rikken, G. L. J. A. J. Chem. Phys. 2002,
117, 11315; Krstic, V.; Rikken, G. L. J. A. Chem. Phys. Lett. 2002, 364, 51; Rikken,
G. L. J. A.; Folling, J.; Wyder, P. Phys. Rev. Lett. 2001, 87, 236602.
3. Avarvari, N.; Wallis, J. D. J. Mater. Chem. 2009, 19, 4061.
4. Yang, S.; Brooks, A. C.; Martin, L.; Day, P.; Li, H.; Horton, P.; Male, L.; Wallis, J. D.
CrystEngComm 2009, 11, 993; Gomar-Nadal, E.; Rovira, C.; Amabilino, D. B.
Tetrahedron 2006, 62, 3370.
5. Wallis, J. D.; Griffiths, J.-P. J. Mater. Chem. 2005, 15, 347.
6. Dunitz, J. D.; Karrer, A.; Wallis, J. D. Helv. Chim. Acta 1986, 69, 69; Karrer, A.;
Wallis, J. D.; Dunitz, J. D.; Hilti, B.; Mayer, C. W.; Bürkle, M.; Pfeiffer, J. Helv.
Chim. Acta 1987, 70, 942; Freund, M. M.; Olsen, J. L.; Wallis, J. D.; Karrer, A.;
Dunitz, J. D.; Hilti, B. Jpn. J. Appl. Phys., Part 1 1987, 26, 895.
7. Zambounis, J. S.; Mayer, C. W.; Hauenstein, K.; Hilti, B.; Hofherr, W.; Pfeiffer, J.;
Buerkle, M.; Rihs, G. Adv. Mater. 1992, 4, 33.
8. Matsumiya, S.; Izuoka, A.; Sugawara, T.; Taruishi, T.; Kawada, Y.; Tokumoto, M.
Bull. Chem. Soc. Jpn. 1993, 66, 1949.
9. Griffiths, J.-P.; Hui, N.; Brown, R. J.; Day, P.; Wallis, J. D. Org. Biomol. Chem. 2005,
3, 2155.
10. Brown, R. J.; Brooks, A. C.; Griffiths, J.-P.; Vital, B.; Day, P.; Wallis, J. D. Org.
Biomol. Chem. 2007, 5, 3172.
11. Réthoré, C.; Avarvari, N.; Canadell, E.; Auban-Senzier, P.; Fourmigué, M. J. Am.
Chem. Soc. 2005, 127, 5748; Réthoré, C.; Fourmigué, M.; Avarvari, N. Tetrahedron
2005, 61, 10935; Réthoré, C.; Madalan, A.; Fourmigué, M.; Canadell, E.; Lopes, E.
B.; Almeida, M.; Clerac, R.; Avarvari, N. New J. Chem. 2007, 31, 1468.
12. Chas, M.; Lemarié, M.; Gulea, M.; Avarvari, N. Chem. Commun. 2008, 220; Chas,
M.; Riobé, F.; Sancho, R.; Minguíllon, C.; Avarvari, N. Chirality 2009, , doi:10.
1002/chir.20692
unique reflections, 5045 with F2>2
data)¼0.043.
s
, R(F, F2>2
s
)¼0.017, Rw(F2, all
Crystal data for 12: C13H14S5, Mr¼426.72, triclinic, a¼6.8624(5),
b¼7.0519(5), c¼9.5071(7) Å,
a
¼80.453(4),
b
¼83.676(4), ¼75.465
g
(3)ꢀ, V¼438.05(5) Å3, Z¼1, P1, Dc¼1.62 g cmꢁ3
,
m
¼1.01 mmꢁ1
,
T¼150 K, 6275 unique reflections, 5989 with F2>2
0.020, Rw(F2, all data)¼0.048.
s
, R(F, F2>2
s)¼
Crystal data for 14: C17H16S8, Mr¼476.78, monoclinic, a¼7.7420
(4), b¼14.2133(8), c¼18.0225(11) Å,
b
¼90.418(3)ꢀ, V¼1983.13(19)
Å3, Z¼4, P21, Dc¼1.60 g cmꢁ3
,
m
¼0.90 mmꢁ1, T¼120 K, 4594 unique
reflections, 3746 with F2>2
s
, R(F, F2>2
s
)¼0.044, Rw(F2, all data)¼
0.101. One of the two independent molecules is disordered about
the long molecular axis, so that there are two positions (in a ratio
e3:2) for the 6,6-dimethylbicyclo[3.1.1]heptene-2,3-dithio unit.19
Crystal data for 12$I3: C13H14S8$I3, Mr¼807.42, monoclinic,
a¼8.2507(6), b¼13.8305(13), c¼20.3877(18) Å,
b
¼99.998(4)ꢀ,
V¼2291.1(3) Å3, Z¼4, P21, Dc¼2.34 g cmꢁ3
,
m
¼4.82 mmꢁ1, T¼120 K,
5987 unique reflections, 5392 with F2>2
Rw(F2, all data)¼0.141.
s
, R(F, F2>2
s)¼0.044,
Crystal data (synchrotron) for (13)3(I3)3$chlorobenzene:
(C13H14S8)3$(I3)3$C6H5Cl, Mr¼2793.03, monoclinic, a¼13.441(3),
b¼14.338(8), c¼21.160(4) Å,
b
¼95.39(3)ꢀ, V¼4059.8(14) Å3, Z¼2,
P21, Dc¼2.20 g cmꢁ3
,
m
¼4.12 mmꢁ1, T¼120 K, 11,613 unique re-
flections, 7909 with F2>2
s
, R(F, F2>2
s
)¼0.052, Rw(F2, all data)¼
13. Martin, L.; Turner, S. S.; Day, P.; Abdul Malik, K. M.; Coles, S. J.; Hursthouse, M. B.
Chem. Commun. 1999, 513.
14. Coronado, E.; Galán-Mascarós, J. R.; Gómez-Garcia, C. J.; Murcia-Martinez, A.;
Canadell, E. Inorg. Chem. 2004, 43, 8072.
15. Martin, L.; Day, P.; Akutsu, H.; Yamada, J.-I.; Nakatsuji, S.; Clegg, W.; Harrington,
R. W.; Horton, P. N.; Hursthouse, M. B.; McMillan, P.; Firth, S. CrystEngComm
2007, 9, 865.
16. Kobayashi, N.; Naito, T.; Inabe, T. Adv. Mater. 2004, 16, 1803.
17. Brooks,A. C.;Day, P.;Wallis, J. D. Acta Crystallogr., Sect. C2008, 64, o245;Porter, L. C.;
Kini, A. M.; Williams, J. M. Acta Crystallogr., Sect. C 1987, 43, 998; Dautel, O. J.;
Formigué, M. J. Org. Chem. 2000, 65, 6479.
0.110.
Crystal data for 13$TCNQ: C17H18S8$C12H4N4, Mr¼683.0, triclinic,
a¼7.2400(7), b¼7.8327(6), c¼27.247(3) Å,
a
¼87.572(5),
b
¼87.761
(3),
g
¼76.405(2)ꢀ, V¼1499.8(2) Å3, Z¼2, Pꢁ1, Dc¼1.51 g cmꢁ3
,
,
m
¼0.62 mmꢁ1, T¼120 K, 6530 unique reflections, 3707 with F2>2
s
R(F, F2>2
s
)¼0.12, Rw(F2, all data)¼0.23. The structure is modelled
with a 72:28 disorder between enantiomers.19
Crystal data (synchrotron) for 14$TCNQ: C17H16S8$C12H4N4,
Mr¼680.97, orthorhombic, a¼7.877(6), b¼13.630(10), c¼27.69(2) Å,
18. Svenstrup, N.; Becher, J. Synthesis 1995, 215; Wang, C.; Batsanov, A. S.; Bryce, M. R.;
Howard, J. A. K. Synthesis 1998, 1615.
19. Details in Supplementary data.
V¼2973(4) Å3, Z¼4, P212121, Dc¼1.52 g cmꢁ3
,
m
¼0.57 mmꢁ1
,
T¼120 K, 3638 unique reflections, 1760 with F2>2
s
, R(F, F2>2
s
)¼
20. Ward, H.; Granroth, G. E.; Abboud, K. A.; Meisel, M. W.; Talham, D. R. Chem.
Mater. 1998, 10, 1102.
21. Guionneau, P.; Kepert, C. J.; Bravic, G.; Chasseau, D.; Truter, M. R.; Kurmoo, M.;
Day, P. Synth. Met. 1997, 86, 1973.
22. Wang, H. H.; Ferraro, J. R.; Williams, J. M.; Geiser, U.; Schlueter, J. A. J. Chem. Soc.,
Chem. Commun. 1994, 1893.
23. Resistance greater than 200 MOhms.
24. A partial solution of X-ray diffraction data collected for the material from 1,1,1-
trichloroethane showed that the donor cations are arranged in face-to-face
pairs, and triiodides are integrated into the donor packing arrangement.
There is also one molecule of trichloroethane for each two donors and two
triodides, packed among the hydrocarbon residues of the donors. Unit cell:
0.058, Rw(F2, all data)¼0.129.19
Crystal data for 15$TCNQ: C20H22S8$C12H4N4, Mr¼723.05, or-
thorhombic, a¼7.8793(8), b¼27.888(3), c¼29.721(3) Å, V¼6530.8
(12) Å3, Z¼8, P212121, Dc¼1.47 g cmꢁ3
,
m
¼0.58 mmꢁ1, T¼120 K,
13,554 unique reflections, 9479 with F2>2
s
, R(F, F2>2
s)¼0.097,
Rw(F2, all data)¼0.199.19
triclinic, a¼9.8926(12), b¼12.8696(15), c¼22.078(3) Ǻ,
a
¼92.212(4),
b
¼95.39
Acknowledgements
(3),
g
¼90.591(5)ꢀ.
25. Mori, T.; Inokuchi, H. Solid State Commun. 1986, 59, 355; Mori, T.; Inokuchi, H.
Bull. Chem. Soc. Japan 1987, 60, 402; Yamamoto, H. M.; Hagiwara, M.; Kato, R.
Synth. Met. 2003, 133e134, 449.
We thank the EPSRC for grant EP/C510488/1 and for a student-
ship (ACB), the EPSRC National Crystallography Service for datasets,
the EPSRC Mass Spectrometry Service for measurements, STFC and
Diamond Light Source for access to synchrotron facilities, SRS sta-
tion 9.8 staff, and the Diamond beamline I19 staff led by Dr. David
Allan for advice and assistance with the use of the new facility. We
thank Prof. S. Nakasuji, Hyogo University, Japan, for access to
equipment for conductivity measurements. The work has benefited
26. Guinneau, P.; Chasseau, D.; Howard, J. A. K.; Day, P. Acta Crystallogr., Sect. C
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27. Herbstein, F.H. “Crystalline Molecular Complexes and Compounds”, Chapter 13,
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