Dinaphtho[2′,3′:5,6][1,4]dithiino[2,3-b:2,3-e]pyridine, its 16-butyl derivative and dinaphtho[2′,3′:5,6][1,4]dioxo[2,3-b:2,3-e]pyridine: Novel heterocycles as electron donor compounds

Article abstract of DOI:10.1039/b202708a

Dinaphtho[2′,3′:5,6][1,4]dithiino[2,3-b:2,3-e]pyridine (4a), its 16-butyl derivative (4b), and dinaphtho[2′,3′:5,6][1,4]dioxo[2,3-b:2,3-e]pyridine (5) have been prepared and fully characterized. The electrochemical properties of 4a, 4b and 5 have been studied by cyclic voltammetry in CH₂Cl₂:trifluoroacetic acid (1:1); in agreement with their donor character, they exhibit a first reversible oxidation wave to their radical cations with very similar potential peak values and a second irreversible wave to their dications, the lowest potential peak value of this second oxidation corresponding to 5. Their radical cations, generated by oxidation of the parent compounds, are relatively stable and have been analyzed in liquid solution by electron paramagnetic resonance (EPR). Spin density distributions in the SOMO have been calculated by the semiempirical MNDO method. Electronic spectra of 4a and 4b in trifluoroacetic acid show peaks at 417 and 401 nm, respectively, and in the presence of thallium(III) trifluoroacetate two characteristic peaks at λ_max 411 and 868 nm for 4a^·+, and at 411 and 872 nm for 4b^·+. X-Ray analysis of 4b shows a molecular structure with a stable chair-shaped conformation with interplanar angles between naphthalenes and the pyridine ring of 139.0(1) and 146.4(1)°.

Full text of DOI:10.1039/b202708a

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Dinaphtho[20,30:5,6][1,4]dithiino[2,3-b:2,3-e]pyridine, its 16-butyl
derivative and dinaphtho[20,30:5,6][1,4]dioxo[2,3-b:2,3-e]pyridine:
novel heterocycles as electron donor compounds
a
Carlos Troya, Albert Vidal, Enric Brillas, Jordi Rius, Xavier Torrelles, Carlos Aleman,
b
c
d
d
e
´
f
Jordi Casanovas and Luis Julia*
a
´
a
´
Departament de Quımica Organica Biologica, Centre d’Investigacio i Desenvolupament
(CSIC), Jordi Girona 18-26, 08034, Barcelona, Spain
`
`
´
b
c
´
Departament de Quımica Organica, CETS Institut Quımic de Sarria, Universitat
Ramon Llull, 08017, Barcelona, Spain
`
´
`
´
Departament de Quımica Fısica, Universitat de Barcelona, Diagonal 647, 08028,
´
Barcelona, Spain
d
e
`
Institut de Ciencia de Materials (CSIC), Campus de la U.A.B., 08193, Bellaterra, Spain
Departament d’Enginyeria Quımica, ETS d’Enginyers Industrials de Barcelona, Universitat
´
´
Politecnica de Catalunya, Diagonal 647, 08048, Barcelona, Spain
Departament de Quımica, Escola Universitaria Politecnica, Universitat de Lleida, Jaume II 69,
f
´
´
25001, Lleida, Spain
Received (in Montpellier, France) 8th March 2002, Accepted 16th May 2002
First published as an Advance Article on the web 5th September 2002
Dinaphtho[20,30:5,6][1,4]dithiino[2,3-b:2,3-e]pyridine (4a), its 16-butyl derivative (4b), and
dinaphtho[20,30:5,6][1,4]dioxo[2,3-b:2,3-e]pyridine (5) have been prepared and fully characterized. The
electrochemical properties of 4a, 4b and 5 have been studied by cyclic voltammetry in CH2Cl2:trifluoroacetic
acid (1:1); in agreement with their donor character, they exhibit a first reversible oxidation wave to their radical
cations with very similar potential peak values and a second irreversible wave to their dications, the lowest
potential peak value of this second oxidation corresponding to 5. Their radical cations, generated by oxidation
of the parent compounds, are relatively stable and have been analyzed in liquid solution by electron
paramagnetic resonance (EPR). Spin density distributions in the SOMO have been calculated by the
semiempirical MNDO method. Electronic spectra of 4a and 4b in trifluoroacetic acid show peaks at 417 and
401 nm, respectively, and in the presence of thallium(III) trifluoroacetate two characteristic peaks at lmax 411
and 868 nm for 4aꢀ+, and at 411 and 872 nm for 4bꢀ+. X-Ray analysis of 4b shows a molecular structure with a
stable chair-shaped conformation with interplanar angles between naphthalenes and the pyridine ring of
139.0(1) and 146.4(1)ꢁ.
Thianthrene (1) (Scheme 1) and substituted thianthrenes give
strongly coloured solutions when dissolved in concentrated
sulfuric acid1 or in other oxidant systems2 due to the formation
of persistent radical cations which have been detected by elec-
tron paramagnetic ꢀ resonance (EPR) spectroscopy. Under
aprotic conditions 1 + has been isolated as a radical cation salt
with AlCl4ꢂ as a counter ion and its crystal structure analyzed
lar behaviour in EPR, the splittings in the spectruꢀm of its radi-
cal cation are practically equal to those found in 1 + suggesting
that the SOMO does not show any estimable perturbation in
spite of the asymmetry of the molecule.5 The stability of these
charged species is due to delocalization of the unpaired elec-
tron over the whole system. Expanding the p system to
multi-ring molecules, we have also reported the new hetero-
cycle di[1,4]benzodithiino[2,3-b:2,3-e]pyridine (3) (Scheme
1),5,6 a stable chair-shaped conformation with interplanar
angles between phenyls and pyridine rings (when R ¼ H in
3) of 135ꢁ.5 In the EPR spectrum of 3ꢀ+, the splitting of the
electron spin with hydrogens was rationalized by complete
planarization of the molecule as a consequence of the removal
of one electron.
by X-ray diffraction.2d The bent molecular structure of 13 is
ꢀ+ 2d
considerably flattened upon oxidation to 1
.
As a conse-
quence of these properties, thianthrenes have gained new inter-
est as electron donor components in charge transfer
complexes.2d,4 Oxidation of 1-azathianthrene (2) showed simi-
Searching for new p-electron systems with electron donating
properties, now we report the synthesis and electrochemical
behaviour of three novel heptacenes, two tetrathioheptacenes,
dinaphtho[20,30:5,6][1,4]dithiino[2,3-b:2,3-e]pyridine (4a) and
its 16-butyl derivative (4b), and one tetraoxoheptacene,
dinaphtho[20,30:5,6][1,4]dioxino[2,3-b:2,3-e]pyridine (5). The
EPR spectra of their radical cations have been recorded. In
addition, we also report the molecular structure of 4b
and compare it with that of a new tetraoxopentacene,
Scheme 1
1308
New J. Chem., 2002, 26, 1308–1313
DOI: 10.1039/b202708a
This journal is # The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2002

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di[1,4]benzodioxino[2,3-b:2,3-e]pyridine (6), due to the difficul-
ties of obtaining good crystals for X-ray analysis from 5.
to these results, the chair-shaped conformation observed for
4b seems to be favored by packing interactions.
A completely different situation was found for 5. In this
case, the lowest energy conformation corresponds to the pla-
nar arrangement, the chair-shaped and boat-shaped conforma-
Results and discussion
tions being less favored by 2.93 and 0.84 kJ molꢂ1
,
The heptacenes 4a, 4b and 5, and pentacene 6 were prepared as
shown in Scheme 2, starting from 2,3,5,6-tetrachloropyridine
and using the same methodology reported for 3.5–7 In the
synthesis of intermediates 2,3-dichloronaphtho[20,30:5,6]-
[1,4]dithiino[2,3-b]pyridines (7a) and (7b), and 2,3-dichloro-
[1,4]benzodioxino[2,3-b]pyridine (8), small quantities of
by-products 9a, 9b, and 10 were also obtained.
Due to the poor solubility of 4a in organic solvents, only
good crystals for X-ray analysis were obtained from azate-
trathiaheptacene 4b. Its molecular structure shows a general
chair-shaped conformation with interplanar angles between
naphthalenes and pyridine of 139.0(1)ꢁ and 146.4(1)ꢁ, slightly
larger than the angles between benzenes and pyridine in aza-
tetrathiapentacene 3 (135ꢁ)5 and between peripheral and cen-
tral benzenes in tetrathiapentacene 11 (131.5ꢁ)8 (Scheme 1).
Also due to difficulties with carrying out an X-ray analysis
of azatetraoxoheptacene 5, we have studied the molecular
structure of the azatetraoxopentacene 6 and compared it with
that of 4b as shown in Fig. 1 (the butyl substituent has been
omitted from the structure of 4b for clarity). The structure of
6 confirms the planar geometry of the stable conformation
(Fig. 1b) with dihedral angles between benzenes and pyridine
of 179.17(1)ꢁ and 173.84(1)ꢁ. This result suggests that the
structure of 5 should also be planar.
respectively. These theoretical results for 5 and the observed
results for the structure of 6 indicate that in the tetraoxo spe-
cies the planar arrangement is an intrinsic conformational
property and not an effect of the packing interactions.
When degassed solutions of 4a (10ꢂ3 M) in benzene contain-
ing trifluoroacetic acid (TFA) (10% v/v) were treated at room
temperature with thallium(III) trifluoroacetate (TTA) an EPR
spectrum with a multipletꢀ of peaks was obtained. Fig. 2a
+
shows the spectrum of 4a and its simulation12 using the
hyperfine splitting (hfs) values showed in Table 1. Under con-
ditions of over-modulation and high amplification the hfs due
to the coupling of the electron with naturally abundant 33S
(0.76%) were observed as two multiplet satellite lines
(a ¼ 4.7 G) which corresponds to the MS ¼ ꢃ3/2 groups of
the quartet [I(33S) ¼ 3/2], the two MS ¼ ꢃ1/2 groups being
lost into the very intense central multiplet. Likewise, the spec-
ꢀ
+
trum of 4b appeared as a multiplet when degassed solutions
of 4b in CH2Cl2–TFA (1:1) were irradiated with a UV lamp at
ꢀ
+
low temperature (ꢂ10 ꢁC). The coupling values in 4b (Table
1) are similar to those in 4aꢀ+. The recorded spectrum when
tetraoxoheptacene 5 in TFA was treated with TTA (Fig. 2b)
consisted of a very strong multiplet centered at lower g-value
with the hfs values showed in Table 1. The assignation of the
hfs values to the different hydrogens of the radical cation spe-
cies in Table 1 has been carried out by considering our pre-
vious work on azatetrathiopentacenes.5,6
Quantum mechanical calculations (MNDO method)9 for 4a
and 5 were performed to investigate the influence of the hetero-
atoms on the intrinsic conformational preferences of these
compounds. For 4a, the chair-shaped and the boat-shaped
conformations were isoenergetic, the planar arrangement
being only 1.25 kJ molꢂ1 higher in energy. These results indi-
cate that the two folded conformations are equally preferred,
the barrier between them being almost negligible. According
A comparative analysis of the spectra of 4aꢀ+ and 4bꢀ+, with
ꢀ
+
the spectrum of 5 shows a clear difference in the electron
coupling with the nitrogen and the hydrogen of the pyridine
ring, this coupling being higher in 5ꢀ+. On the other hand,
ꢀ
+
the high values of coupling with the sulfur atoms in 4a
and 4b suggest that the major spin density in these radical
ꢀ
+
Scheme 2
New J. Chem., 2002, 26, 1308–1313
1309

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Fig. 1 (a) Molecular structure of 4b (butyl substituent has been
omitted to clarify the difference in the dihedral angles between the
structures of 4b and 6). (b) Molecular structure of 6.
cations resides in these heteroatoms and, consequently, they
Fig. 2 (a) EPR spectra ofꢀdinaphtho[20,30:5,6][1,4]dithiino[2,3-b:2,3-
e]pyridine radical cation (4a +) generated from the neutral compound
in benzene containing TFA (10% v/v) with thallium(III) trifluoroace-
tate at rt: (a1) experimental, (a2) simulated spectrum using the hfs
values given in the text. (b) EPR spectra of dinaphtho[20,30:5,6]-
[1,4]dioxino[2,3-b:2,3-e]pyridine radical cation (5ꢀ+) generated from
the neutral compound in TFA with thallium(III) trifluoroacetate at
rt: (b1) experimental, (b2) simulated spectrum using the hfs values given
in the text.
ꢀ
+
show greater g values than 5 (Table 1).
All these results are in good agreement with theoretical cal-
ꢀ
+
culations.9 Thus, complete geometry optimization of 4a led
to an almost planar conformation. The interplanar angles
found for this minimum were 174.6 and 175.2ꢁ, the reduction
with respect to the neutral compound being about 24ꢁ.ꢀFig. 3
shows atomic coefficients in the SOMO computed for 4a + and
5ꢀ+ꢀ . The orbital ꢀis mainly located in the S-containing rings in
+
4a +, while in 5 the orbital is distributed along the whole
molecule.
(CV) among the first anodic peak potentials of tetrathiohepta-
cenes 4a, 4b and tetraoxoheptacene 5, but the second anodic
potential of 5 is shifted to less positive potentials relative to
those of 4a and 4b. Values of DEa (Table 2) are a measure of
the intramolecular coulombic repulsion resulting from two
positive charges in the molecule. The lowest value of DEa in
5 is in agreement with the fact that charges in 52+ are further
apart from each other than in 4a2+ and 4b2+. CV of 4b (ꢄ10ꢂ3
M) in carefully dried CH2Cl2 (twice distilled from phosphorus
pentoxide) with alumina suspended in the solution and con-
taining 0.1 M tetrabutylammonium hexafluorophosphate at v
ranging from 20 mV sꢂ1 to 200 mV sꢂ1 exhibited one well-
defined but irreversible oxidation peak O1 , with an anodic
peak potential Epa(O1) ¼ 1.24 V vs. SCE at 100 mV sꢂ1. The
loss of reversibility of this process may be attributed to an
Cyclic voltammogram of 4a, 4b and 5 in CH2Cl2:TFA (1:1)
containing tetrabutylammonium perchlorate exhibited at a
scan rate (v) ranging from 20 mV sꢂ1 to 200 mV sꢂ1 and at
25 ꢁC a quasi-reversible redox pair O1/R1 with anodic peak
1
potentials (Ea ) and standard potentials (Eꢁ) as depicted in
Table 2. These couples are ascribed to the equilibrium between
neutral species and their radical cations and they are indicative
of the stability of these radical cations in the medium. When
the scan potential was increased a second oxidation peak O2
appeared at v ¼ 200 mV sꢂ1 with anodic peak potentials
2
(Ea ) also shown in Table 2. These second irreversible pro-
cesses should correspond to the oxidation of the radical
cations to their dications which are not stable in the medium.
No significant differences were observed in cyclic voltammetry
Table 1 Experimental hyperfine coupling constants (a) in Gauss, calculated spin densities in parentheses and other EPR parameters for radical
ꢀ
ꢀ
ꢀ
+
cations 4a +, 4b +, and 5
aH
aN
aS
g
DHpp
ꢀ
+
4a
0.46(0.031)(1H)a
0.24(0.041)(4H)b
0.24(0.048)(4H)c
< 0.1(0.040)(4H)
0.42(2H)a
0.82(0.090)(1N)
4.7(0.136)(4S)
2.0077
0.2
ꢀ
+
4b
0.79(1N)
4.6(4S)
2.0079
2.0036
0.18
0.11
0.21(8H)b c
< 0.1(4H)d
ꢀ
+
5
1.0(0.041)(1H)a
0.31(0.036)(4H)b
0.18(0.036)(4H)c
1.48(0.095)(1N)
a
Hydrogens in position 16. b Hydrogens in positions 5, 9, 14, and 18. c Hydrogens in positions 2, 3, 11, and 12. d Hydrogens in positions 1, 4, 10,
and 13.
1310
New J. Chem., 2002, 26, 1308–1313

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0.093 cm2 was used as the working electrode and a Pt wire
as the counter electrode. The reference electrode was a calomel
electrode (SSCE) with a NaCl-saturated aqueous solution,
submerged in a salt bridge of the same electrolyte, which was
separated from the cell by a Vycor membrane. Solutions of
4b (ꢄ10ꢂ3 M) in CH2Cl2 or in CH2Cl2:TFA (1:1) containing
tetrabutylammonium perchlorate (0.1 M) as background elec-
trolyte were studied by CV. The volume of all test solutions
was 25 mL. The CV measurements were performed with a
standard equipment consisting of a PAR 175 universal pro-
grammer, an Amel 551 potentiostat, and a Phillips 8043 X–Y
recorder. Cyclic voltammograms of all solutions were recorded
ꢀ
ꢀ
+
Fig. 3 Atomic coefficients in the SOMO computed for 4a + and 5
.
with scan rates (v) ranging from 20 to 200 mV sꢂ1
.
ion-pairing effect based on the irreversible interaction of the
hexafluorophosphate counterion with the radical cation.
Absorption peaks in the visible region for the electronic
spectra of solutions of 4a and 4b in TFA were at lmax/nm
(e/dm3 molꢂ1 cmꢂ1) ¼ 417 (9900) and 401 (11 450), respec-
tively. In the presence of TTA, absorption peaks appeared at
lmax 411 and 868 nm, and at 411 and 872 nm, attributed to
EPR experiments
EPR spectra were recorded with a Varian E-109 Spectrometer
working in the X band using a Varian E-257 temperature con-
troller. Solutions (ꢄ10ꢂ3 M) of compounds 4a, 4b and 5 in tri-
fluoroacetic acid (TFA) or in mixtures of TFA and CH2Cl2 ,
with or without thallium(III) trifluoroacetate (TTFA) being
added as oxidant, were placed in quartz EPR tubes and deox-
ygenated by bubbling argon through them for 5 min and then
transferred to the EPR cavity.
ꢀ
ꢀ
4a and 4b +, respectively. From the decay of the intensities
of these absorbance peaks with time, the half lifetimes of both
charged species could be estimated to be y ꢄ 30 min. We have
no satisfactory results from 5 due to its poor solubility. In the
presence of SbCl5 solutions of 4b in CHCl3 yielded a yellow
and stable salt characterized as 4b2+ꢅ2SbCl6ꢂ. All attempts
to get crystals for an X-ray analysis of this salt proved to be
unsuccessful.
+
2,3-Dichloronaphtho[20,30:5,6][1,4]dithiino[2,3-b]pyridine (7a)
A mixture of naphthalene-2,3-dithiol (0.44 g; 2.31 mmol),
2,3,5,6-tetrachloropyridine (0.5 g; 2.31 mmol), sodium bicar-
bonate (0.82 g), and DMF (25 mL) was stirred under argon
at 100 ꢁC for 2.5 h and then refluxed for 4 h. The mixture
was cooled, poured into water, acidified with hydrochloric acid
and filtered. The precipitate was chromatographed (silica gel)
and eluted with CCl4 to give: (a) 2,20-(naphthalene-2,3-dithio)-
bis(3,5,6-trichloropyridine) (9a) (0.19 g, 30%); dH 8.29 (s, 2H),
7.92–7.88 (m, 2H), 7.63 (s, 2H), 7.64–7.60 (m, 2H). (b) 7a (0.39
g; 51%); dH 7.95 (s, 1H), 7.94 (s, 1H), 7.79 (s, 1H), 7.74–7.78
(m, 2H), 7.53–7.47 (m, 2H); IR (KBr) nmax/cmꢂ1 3030 (w),
1510 (w), 1485 (w), 1360 (s), 1340 (m), 1310 (m), 1220 (m),
1155 (m), 1110 (w), 1065 (m), 1055 (w), 885 (m), 870 (m),
735 (m), 715 (w), 620 (m). Anal. Calc. for C15H7Cl2NS2 : C,
53.6; H, 2.1; Cl, 21.1; N, 4.2; S, 19.1. Found: C, 53,5; H, 2.0;
Cl, 21.6; N, 4.1; S, 19.1%.
Attempts to obtain adducts from dilute solutions of 4a, 4b
and 5, with a good electron acceptor such as 2,3-dichloro-
5,6-dicyanoquinone (DDQ), were not successful due to the
low solubilities of these compounds in most organic solvents;
however, the electronic spectrum of mixtures of 4b and
DDQ showed a very weak and broad band at lmax ¼ 655
nm, characteristic of the presence of a charge transfer complex.
Work is now in progress to introduce substituents in these new
heterocycles to improve their solubilities.
Experimental
Melting points were obtained by using a Ko¨fler microscope
‘‘Reichert’’ and are uncorrected. The IR spectra were recorded
with a FT-IR ‘‘Bomem-Michalson’’ model MB-120 spectro-
photometer. 1H NMR spectra were determined at 200 MHz
and 300 MHz with Varian Gemini 200HC and XL-300 spec-
trometers, respectively. 13C NMR spectra at 75 MH were
obtain with a Varian Gemini 300HC spectrometer. The elec-
tronic spectra were recorded with a Perkin-Elmer Lambda
Array 3840 Spectrometer coupled with a Perkin-Elmer 7300
computer. DMF was used as received. CHCl3 was dried over
calcium chloride and distilled. Naphthalene-2,3-dithiol [1H
NMR (300 MHz, CDCl3) d 7.90 (s, 2H), 7.66 (dd, 2H,
J ¼ 6.0 Hz, J0 ¼ 3.3 Hz), 7.42 (dd, 2H, J ¼ 6.0 Hz, J0 ¼ 3.3
Hz), 3.88 (s, 2H)] was prepared from 1-butanethiol and 2,3-
dibromonaphthalene as described.13
Dinaphtho[20,30:5,6][1,4]dithiino[2,3-b:2,3-e]pyridine (4a)
(i) From 2,3-dichloronaphtho[20,30:5,6][1,4]dithiino[2,3-b]pyr-
idine (7a). A mixture of naphthalene-2,3-dithiol (0.21 g; 1.09
mmol), 7a (0.30 g; 0.89 mmol), sodium bicarbonate (0.40 g),
and DMF (12 mL) was stirred under argon at 100 ꢁC for 1.5
h and then refluxed for 5 h. The mixture was cooled, poured
into water, acidified with hydrochloric acid and filtered. The
precipitate was extracted by a mixture of CCl4–CHCl3 to give
4a (0.20 g; 49%) m.p. 390 ꢁC; dH 7.97 (s, 2H), 7.95 (s, 2H), 7.77
(s 1H), 7.77–7.74 (m, 4H), 7.50–7.46 (m, 4H); IR (KBr) nmax
/
cmꢂ1 3050 (w), 1490 (w), 1430 (w), 1365 (m), 1350 (s), 1310
(w), 1220 (w), 1190 (w), 1160 (m), 1140 (w), 1110 (m), 900
(w), 870 (s), 750 (w), 730 (s), 660 (w), 630 (w). Anal. Calc.
for C25H13NS4 : C, 65.9; H, 2.9; N, 3.1; S, 28.1. Found: C,
65.9; H, 2.8; N, 3.1; S, 28.1%.
Electrochemical measurements
The cyclic voltammetric (CV) experiments were carried out in
a three-electrode cell. A platinum (Pt) disk with an area of
Table 2 Values of anodic peak potentials (Ea) (n ¼ 200 mV sꢂ1) and
redox potentials (Eꢁ) in CH2Cl2:TFA (1:1) with PTBA as electrolyte
(ii) From 2,3,5,6-tetrachloropyridine. A mixture of naph-
thalene-2,3-dithiol (0.89 g; 4.6 mmol), 2,3,5,6-tetrachloropyri-
dine (0.50 g; 2.3 mmol), sodium bicarbonate (1.68 g), and
DMF (50 mL) was allowed to react as described in (i). The
reaction mixture was treated as before, and the crude product
was extracted by CCl4 to give 4a (0.66 g; 63%).
1
Ea (Eꢁ)/V
Ea2/V
DEa/V
4a
4b
5
1.16 (1.11)
1.21 (1.08)
1.08 (1.04)
1.74
1.84
1.52
0.58
0.63
0.44
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4-Butyl-2,3,5,6-tetrachloropyridine
for 1.5 h and then at reflux for 5 h. The reaction mixture
was worked up as before to give: (a) 7b (0.16 g; 8%) and (b)
4b (1.28 g; 85%).
A solution of butylmagnesium bromide [from magnesium
(1.22 g; 0.05 mol) and butylbromide (8.23 g; 0.06 mol) in
diethyl ether] was added dropwise to a solution of penta-
chloropyridine (6.28 g; 0.025 mol) in diethyl ether (50 mL).
The mixture was stirred under argon at rt for 12 h. The reac-
tion mixture was poured into hydrochloric acid (20%) and
extracted with more ether. The ethereal solution, washed with
water and dried over Na2SO4 , was evaporated under reduced
pressure to give a residue which was filtered through silica gel.
Elution with hexane gave 4-butyl-2,3,5,6-tetrachloropyridine
(3.49 g; 52%): bp 138–144 ꢁC/3 mmHg (lit.14 140–145 ꢁC/3
mmHg); dH 3.04–2.96 (m, 2H), 1.51 (m, 4H), 0.98 (t, 3H,
J ¼ 7 Hz); IR (KBr) nmax/cmꢂ1 2960 (s), 2930 (m), 2870
(m), 2860 (m), 1570 (s), 1470 (m), 1460 (m), 1330 (s), 660 (m).
2,3-Dichloro[1,4]benzodioxino[2,3-b]pyridine (8)
A mixture of benzene-1,2-diol (2.06 g; 18.7 mmol), 2,3,5,6-
tetrachloropyridine (3.96 g; 18.2 mmol), sodium carbonate
(4.2 g), and DMF (40 mL) was stirred at reflux under argon
for 6 h. The mixture was cooled, poured into water, acidified
with hydrochloric acid and extracted with diethyl ether. The
ethereal solution was washed with water, dried over Na2SO4
and finally distilled at reduced pressure, to yield a residue
which was chromatographed (silica gel). Elution with CCl4
gave: (a) 2,20-(1,2-phenylenedioxo)bis(3,5,6-trichloropyridine)
(10) (0.76 g; 18%); dH 7.73 (s, 2H), 7.31–7.41 (m, 4H); dC
155.1, 143.9, 143.7, 140.5, 126.5, 123.9, 123.6, 117.2; (b) 8
(3.18g; 69%), m.p. 164–165 ꢁC (from CHCl3–hexane); dH
6.84–7.01 (m, 5H); dC 146.9, 140.9, 140.3, 139.0, 137.2,
126.3, 125.2, 125.0, 117.3, 116.4; IR (KBr) nmax/cmꢂ1 3065
(w), 1570 (m), 1495 (s), 1440 (s), 1375 (m), 1300 (m), 1260
(m), 1195 (m), 1155 (m), 1100 (w), 980 (m), 880 (s), 860 (m),
750 (s), 720 (w). Anal. Calc. for C11H5Cl2NO2 : C, 51.9; H,
2.0; Cl, 27.9; N, 5.5. Found: C, 51.9; H, 2.0; Cl, 28.1; N, 5.5%.
4-Butyl-2,3-dichloronaphtho[20,30:5,6][1,4]dithiino[2,3-b]pyridine
(7b)
A mixture of naphthalene-2,3-dithiol (0.79 g; 4.0 mmol), 4-
butyl-2,3,5,6-tetrachloropyridine (1.09 g; 4 mmol), sodium
bicarbonate (1.5 g), and DMF (45 mL) was stirred under
argon at 100 ꢁC for 1.5 h and then refluxed for 6 h. The mix-
ture was cooled, poured into water, acidified with hydrochloric
acid and filtered. The precipitate was chromatographed (silica
gel) and eluted with CCl4–CHCl3 (5:1) to give: (a) 2,20-(naph-
Di[1,4]benzodioxino[2,3-b:2,3-e]pyridine (6)
thalene-2,3-dithio)bis(4-butyl-3,5,6-trichloropyridine)
(9b)
A mixture of benzene-1,2-diol (1.00 g; 9.1 mmol), 8 (2.00 g; 7.9
mmol), sodium bicarbonate (2.2 g) and DMF (40 mL) was stir-
red at reflux under argon for 16.5 h. The mixture was worked
up as before and the residue was chromatographed (silica gel)
and eluted with CCl4:CHCl3 (3:1) to give 6 (0.95 g; 41%), m.p.
274–276 ꢁC (from hexane); dH 6.79–6.94 (m, 9H); dC 141.4,
140.7, 133.8, 124.6, 124.4, 117.1, 116.2, 114.2; IR (KBr)
(0.49 g; 18%) m.p. 191–193 ꢁC; dH 8.27 (s, 2H), 7.90–7.87 (m,
2H), 7.61–7.58 (m, 2H), 2.93–288 (m, 4H), 1.57–1.42 (m,
8H), 0.97 (t, 6H, J ¼ 7.2 Hz); dC 155.7, 149.6, 146.8, 137.8,
134.0, 131.2, 127.9, 127.6, 127.0, 126.6, 32.3, 29.3, 22.8, 13.8.
Anal. Calc. for C28H24Cl6 N2S2 : C, 50.5; H, 3.6; N, 4.2; S,
9.6. Found: C, 50.4; H, 3.6; N, 4.2; S, 9.6%; (b) 7b (0.88 g;
1
56%) m.p. 159–161 ꢁC; H NMR (300 MHz; CDCl3) d 8.01
n
max/cmꢂ1 3065 (w), 1635 (w), 1590 (w), 1500 (m), 1465 (s),
(s, 1H), 7.97 (s, 1H), 7.78–7.74 (m, 2H), 7.52–7.48 (m, 2H),
3.11–3.06 (m, 2H), 1.62–1.49 (m, 4H), 1.03 (t, 3H, J ¼ 7.2
Hz); 13C NMR 154.7, 150.8, 147.2, 132.7, 132.5, 132.0,
131.0, 129.9, 128.9, 127.5, 127.4, 127.2, 127.2, 127.1, 127.1,
32.9, 30.2, 22.8, 13.8; IR (KBr) nmax/cmꢂ1 3050 (w), 2950
(w), 2930 (w), 2870 (w), 1570 (w), 1520 (m), 1510 (w), 1490
(w), 1320 (m), 880 (s), 750 (s), 640 (s). Anal. Calc. for
C19H15Cl2NS2 : C, 58.2; H, 3.9; N, 3.6; S, 16.3, Found: C,
58.1; H, 3.9; N, 3.5; S, 16.4%.
1450 (s), 1315 (w), 1275 (s), 1225 (m), 1180 (w), 1100 (w),
1030 (w), 940 (m), 920 (w), 880 (m), 810 (w), 780 (w), 745
(s), 715 (w). Anal. Calc. for C17H9NO4 : C, 70.1; H, 3.1; N,
4.8. Found: C, 70.1; H, 3.0; N, 4.7%.
Dinaphtho[20,30:5,6][1,4]dioxino[2,3-b:2,3-e]pyridine (5)
A mixture of naphthalene-2,3-diol (3.85 g; 24.0 mmol), 2,3,5,6-
tetrachloropyridine (2.0 g; 9.2 mmol), sodium bicarbonate (4.8
g), and DMF (100 mL) was stirred at 100 ꢁC for 1 h and then
at reflux for 11 h. The mixture was cooled, poured into diluted
aqueous hydrochloric acid and the precipitate was isolated by
filtration, washed with water and dried. The solid, digested
from hexane and twice from chloroform, gave 5 (1.86 g;
16-Butyldinaphtho[20,30:5,6][1,4]dithiino[2,3-b:2,3-e]pyridine
(4b)
(i) From 4-butyl-2,3-dichloronaphtho[20,30:5,6][1,4]dithiino-
[2,3-b]pyridine (7b). A mixture of naphthalene-2,3-dithiol
(0.19 g; 0.96 mmol), 7b (0.38 g; 0.96 mmol), sodium bicarbo-
nate (1.0 g), and DMF (15 mL) was stirred under argon at
110 ꢁC for 1 h and then at reflux for 6 h. The mixture was
cooled, poured into water, acidified with hydrochloric acid
and filtered. The precipitate was chromatographed (silica gel)
and eluted with CCl4–CHCl3 (5:1) to give: (a) 7b (0.064 g;
10%); (b) 4b (0.26 g; 53%): m.p. 317.5 ꢁC by DSC; dH 8.02
(s, 2H), 7.98 (s, 2H), 7.79–7.73 (m, 4H), 7.53–7.45 (m, 4H),
3.13–3.05 (m, 2H), 1.56 (m, 4H), 1.03 (t, 3H, J ¼ 7.0 Hz); dC
155.6, 149.5, 132.8, 132.8, 132.6, 130.8, 129.8, 127.4, 127.4,
127.3, 127.2, 127.0, 126.9, 32.6, 31.4, 22.9, 14.0; IR (KBr)
51.5%), m.p. 441 ꢁC (decomp.); IR (KBr)
n
max/cmꢂ1
3055(w), 1625 (w), 1510 (m), 1460 (s), 1395 (m), 1360 (m),
1285 (s), 1240 (m), 1200 (m), 1185 (s), 960 (s), 875 (s), 865
(s), 790 (w), 750 (s), 730 (w), 715 (w). Anal. Calc. for
C25H13NO4 : C, 76.7; H, 3.35; N, 3.6; O, 16.3. Found: C,
74.6; H, 3.3; N, 3.6; O, 16.5; Cl, 1.7%.
Hexachloroantimonate of 4b2+
Neat SbCl5 (0.12 mL; 0.98 mmol) was added dropwise by syr-
inge to a stirred solution of 4b (100 mg; 0.19 mmol) in anhy-
drous CHCl3 (30 mL) under an argon atmosphere. The
solution turned yellow and a solid precipitated. The resulting
mixture was stirred for 2.5 h. The precipitate was filtered under
argon and washed thoroughly with anhydrous CHCl3 . The
salt, 4b2+ꢅ2SbCl6 , was dried at 50 ꢁC (0.5 mmHg) to afford a
powder (195 mg; 85%); IR (KBr) nmax/cmꢂ1 3080 (w), 2960
(w), 2910 (w), 2860 (w), 1570 (w), 1550 (m), 1420 (m), 1290
(m), 1280 (m), 880 (s), 750 (s). Anal. Calc. for
C19H21Cl10NS4Sb2 : C, 29.65; H, 1.8; N, 1.2; S, 10.9. Found:
C, 29.7; H, 1.8; N, 1.25; S, 10.9%.
n
max/cmꢂ1 3040 (w), 2950 (w), 2920 (w), 2880 (w), 1570 (w),
1510 (m), 1490 (m), 1310 (s), 880 (s), 740 (s). Anal. Calc. for
C19H21NS4 : C, 68.1; H, 4.1; N, 2.7; S, 25.1. Found: C, 68.1;
H, 3.9; N, 2.8; S, 25.0%.
(ii) From 4-butyl-2,3,5,6-tetrachloropyridine. A mixture of
naphthalene-2,3-dithiol (1.42 g; 7.4 mmol), 4-butyl-2,3,5,6-
tetrachloropyridine (0.80 g; 3.0 mmol), sodium bicarbonate
(2.5 g), and DMF (90 mL) was stirred under argon at 105 ꢁC
1312
New J. Chem., 2002, 26, 1308–1313

View Article Online
X-Ray analysis of 4b
gence to zero), and the maximum and minimum residual elec-
tron density in the final Fourier difference were 0.121 and
Crystal data. Molecular formula C29H21NS4 . Molecular
¯
weight 511.71. Triclinic, P1, no. 2. Cell dimensions
ꢂ0.193 e Aꢂ3, respectively. The SHELXL-93 program17
˚
was used for refinement and plots were made with PLUTON
programs.18
CCDC reference numbers 190862 and 190863. See http://
www.rsc.org/suppdata/nj/b2/b202708a/ for crystallographic
files in CIF or other electronic format.
˚
a ¼ 8.813(2), b ¼ 10.229(1), c ¼ 14.309(3) A, a ¼ 72.49(2),
3
b ¼ 78.36(2), g ¼ 82.90(2)ꢁ, V ¼ 1202.1(4) A , Z ¼ 2,
˚
F(000) ¼ 532, Dc ¼ 1.414 g cmꢂ3, m ¼ 0.41 mmꢂ1, crystal
dimensions 0.62 ꢆ 0.16 ꢆ 0.34 mm, brown coloured.
Data collection. The diffractometer was an Enraf Nonius
CAD4 with a graphite monochromated MoKa radiation,
˚
l ¼ 0.7103 A. Cell parameters were determined from refine-
Acknowledgements
ment of 25 reflections using the CAD4 Express software.15
4614 reflections were measured with 1.0 < 2y < 25.0ꢁ and
index ranges ꢂ10 < h < 10, ꢂ11 < k < 12, 0 < l < 17 in o/
2y scan mode, 0.8 + 0.5 tan(2y) scanwidth and maximum final
scan time of 60 s. 3 standard reflections were measured every
3600 s to check for the intensity variation and 3 more stan-
dards were measured every 50 reflections to check the crystal
orientation. Intensity decay was 2.7% and was corrected.
Support for this research by DGICYT of MEC (Spain)
through project BQU2000-0789-C02-02 and by the ‘‘General-
itat de Catalunya’’ (Grant: GRQ93-8036) is gratefully
acknowledged. The authors express their gratitude to the
´
EPR service of Centre d’Investigacio i Desenvolupament
(CSIC) in Barcelona.
Absorption corrections were made using 9 psi-scans, Tmax
99.81% and Tmin ¼ 63.91%.
¼
References
Resolution and refinement. The structure was solved by direct
methods using SumF-TF16 and refined on F2 with 4232 unique
reflections and 323 parameters. Final R factors: R ¼ 7.83% for
F2 ¼ > 4s(F2), and wR2 ¼ 25.36%, Goof ¼ 1.050 for all data,
1
(a) H. J. Shine and L. Piette, J. Am. Chem. Soc., 1962, 84, 4798;
(b) H. J. Shine, C. F. Dair and R. J. Small, J. Chem. Phys.,
1963, 38, 569.
(a) P. D. Sullivan, J. Am. Chem. Soc., 1968, 90, 3618; (b) H. J.
Shine and P. D. Sullivan, J. Phys. Chem., 1968, 72, 1390;
(c) J. Giordan and H. Bock, Chem. Ber., 1982, 115, 2548; (d )
H. Bock, A. Rauschenbach, C. Na¨ther, M. Kleine and Z. Havlas,
Chem. Ber., 1994, 127, 2043.
2
P
P
P
where R ¼ kFo| ꢂ |Fck/ |Fo|, wR2 ¼ [ w(Fo ꢂ Fc ) /
2
2 2
P
P
w(Fo2)2]1/2
;
w ¼ 1/[ d(Fo2)2 + (0.554P)2 + 0.92P]; P ¼
P
2
2
2
[Max(Fo2,0) + 2Fc ] / 3, Goof ¼ [( w(Fo ꢂ Fc ))/(n ꢂ p)]1/2
(n, number of reflections and p, number of parameters). Final
shifts/esd were less than 0.001 in the last cycle, and the maxi-
mum and minimum residual electron density in the final Four-
´
3
4
S. Larson, O. Simonsen, G. E. Martın, K. Smith and S. Puig-
Torres, Acta Crystallogr., Sect. C: Cryst. Struct. Commun.,
1984, 40, 103.
(a) P. Berges, V. Mansel and G. Klar, Z. Naturforsch., Teil B,
ier difference were 0.74 and ꢂ0.64 e Aꢂ3, respectively. The
˚
´
1992, 47, 211; (b) W. Hinrichs, P. Berges, G. Klair, E. Sanchez-
SHELXL-93 program17 was used for refinement and plots
Martinez and W. Gunsser, Synth. Met., 1987, 20, 357;
(c) H. Bock, A. Rauschenbach, K. Ruppert and Z. Havlas,
were made with the PLUTON program.18
Angew. Chem., Int. Ed. Engl., 1991, 30, 714; (d ) S. Hunig,
¨
K. Sinzger, R. Bau, T. Metzenthin and J. Salbeck, Chem. Ber.,
1993, 126, 465.
X-Ray analysis of 5
´
C. Martı, J. Irurre, A. Alvarez-Larena, J. F. Piniella, E. Brillas,
5
6
Crystal data. Molecular formula C17H9NO4 . Molecular
weight 291.25. Monoclinic, P21/n, no.14. Cell dimensionꢁs:
´
Ll. Fajarı, C. Aleman and L. Julia, J. Org. Chem., 1994, 59, 6200.
B. Bueno, B. Esteve, J. Irurre, E. Brillas, X. Torrelles, J. Rius,
´
´
˚
a ¼ 6.090(2), b ¼ 22.542(6), c ¼ 13.823(3) A, b ¼ 90.24(3) ,
´
A. Alvarez-Larena, J. F. Piniella, C. Aleman and L. Julia,
´
V ¼ 1897.6(9) A , F(000) ¼ 900, Dc ¼ 1.529 g cmꢂ3, m ¼
3
˚
J. Chem. Soc., Perkin Trans. 2, 1999, 1503.
´
(a) R. S. Dainter, L. Julia, H. Suschitzky and B. J. Wakefield, J.
Chem. Soc., Perkin Trans. 1, 1982, 2897; (b) L. Julia´, J. Rius and
H. Suschitzky, Heterocycles, 1992, 34, 1539.
V. N. Nesterov, V. E. Shklover, Y. T. Struchkov, V. A. Sergeev,
V. I. Nedelkin and I. S. Ivanova, Acta Crystallogr., 1986, 42, 720.
Molecular geometries, energies and spin densities were computed
at the semiempirical MNDO10 level, which is known to provide
good results for the family of compounds investigated in the
present work.5,6 Calculations for the neutral compounds and the
radical cations were performed using the RHF and UHF
methods, respectively. Spin densities were computed using the
0.111 mmꢂ1, crystal dimensions 0.77 ꢆ 0.17 ꢆ 0.12 mm.
7
Data collection. The diffractometer was an Enraf Nonius
CAD4 with graphite monochromated MoKa radiation,
8
9
˚
l ¼ 0.71073 A. Cell parameters were determined from refine-
ment of 15 reflections using the CAD4 Express software.15
4193 reflections were measured with 2.33 p y p 26.28ꢁ and
index ranges 0 p h p 7, ꢂ28 p k p 0, ꢂ17 p l p 17 in o/2y
mode, 0.58 + 0.60 tan(y) scanwidth and maximum final scan
time of 60 s. 3 standard reflections were measured every 3600
s to check for the intensity variation and 3 more standards
were measured every 55 reflections to check the crystal orienta-
tion. There was no intensity loss. Absorption correction was
made using 9 psi-scans, Tmax ¼ 98.62% and Tmin ¼ 92.88%.
EPR keyword implemented in the MOAC93 Revision
2
program.11
10 M. J. S. Dewar and W. Thiel, J. Am. Chem. Soc., 1985, 107, 3902.
11 J. J. P. Stewart, MOPAC 93 Revision 2, Fujitsu Limited.
12 The simulation was performed by using the WINSIM program
provided by D. Dulog, Public EPR Software Tools,
National Institute of Environmental Health Sciences, Bethesda,
MD, 1996.
13 R. Gleiter and J. Vischmann, J. Org. Chem., 1986, 51, 370.
14 S. S. Dua and H. Gilman, J. Organomet. Chem., 1968, 12, 234.
15 CAD4-Express Operating Software, V. 5.1, Enraf-Nonius,
Delft Instruments X-Ray Diffraction, Delft, The Netherlands,
1992.
16 J. Rius, Acta Crystallogr., Sect. A, 1993, 49, 406.
17 G. M. Sheldrick, SHELXL-93, A program for the refinement of
crystal structures, Go¨ttingen University, 1993.
18 A. L. Spek, PLUTON, A program for Display and Analysis of
Crystal and Molecular Structures, Utrecht University, 1993.
Resolution and refinement. The structure was solved by direct
methods using SumF-TF16 and refined on F2 with 3830 unique
reflections and 321 parameters. Final R factors: [I > 2s(I)]
R1 ¼ 0.0419 and wR2 ¼ 0.0975; R factors (all data) R1 ¼
0.1439 and wR2 ¼ 0.1117. Goodness-of-fit on F2 ¼ 0.796,
P
P
P
2
2 2
where R ¼ kFo| ꢂ |Fck/ |Fo|, wR2 ¼ [ w(Fo ꢂ Fc ) /
P
P
w(Fo2)2]1/2
,
w ¼ 1/[ d(Fo2)2 + (0.0594P)2 + 0.00P], P ¼
P
[Max(Fo2,0) + 2Fc ]/3, GooF ¼ [( w(Fo ꢂ Fc ))/(n ꢂ p)]1/2
(n, number of reflections and p, number of parameters). Final
shifts/esd were less than 0.000 in the last cycle (with conver-
2
2
2
New J. Chem., 2002, 26, 1308–1313
1313