New polysulfur-nitrogen heterocycles by thermolysis of 1, 3λ4δ2,2,4-benzodithiadiazines in the hydrocarbon and fluorocarbon series

Article abstract of DOI:10.1002/ejic.200500383

In contrast to thermolysis of 1,3λ⁴δ²,2, 4-benzodithiadiazine (1) and its 5,6,7,8-tetrafluoro derivative 2 in dilute (10^-3 M) hydrocarbon solutions, which leads to persistent 1,2,3-benzodithiazolyls in nearly quantitative

Full text of DOI:10.1002/ejic.200500383

FULL PAPER
New Polysulfur-Nitrogen Heterocycles by Thermolysis of 1,3λ4δ2,2,4-
Benzodithiadiazines in the Hydrocarbon and Fluorocarbon Series
Vladimir V. Zhivonitko,[a,b] Alexander Yu. Makarov,[a] Irina Yu. Bagryanskaya,[a]
Yuri V. Gatilov,[a] Makhmut M. Shakirov,[a] and Andrey V. Zibarev*[a,c]
Keywords: Fluorescence / Fluorine / Nitrogen heterocycles / Radicals / Sulfur heterocycles / Thermolysis
In contrast to thermolysis of 1,3λ4δ2,2,4-benzodithiadiazine
(1) and its 5,6,7,8-tetrafluoro derivative 2 in dilute (10–3
hydrocarbon solutions, which leads to persistent 1,2,3-benzo-
as the 6-7 (4) and 5-6 (16) bicyclic derivatives, confirmed by
X-ray diffraction. The crystal packing of 6 and 11–16 is dis-
cussed with special emphasis on π-stacking interactions. The
M)
dithiazolyls in nearly quantitative yields, the thermolysis of 1 fluorescent properties of the 5-6-6-6 systems synthesized are
and 2 (the 6-6 bicyclic system) in concentrated (0.5
M) solu-
reported. An alternative approach to the linear 5-6-6-6 sys-
tions at 150–170 °C results in complex mixtures of various
polysulfur-nitrogen heterocycles, in particular differently
fused 5-5-6, 5-6-7 and 5-6-6-6 polycyclic systems that were
previously unknown. The products were isolated by column
chromatography, and the structures of the 5-5-6 (11, 12), 5-
6-7 (5, 13), and 5-6-6-6 (6, 14, 15) polycyclic systems, as well
tem 15 based on self-condensation of an R–N=PPh3 precursor
(R
= 4,5,6,7-tetrafluoro-1,2,3-benzodithiazol-2-yl) is de-
scribed, and the free-radical character of this new reaction is
proved.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
(Herz salts). It should be emphasized that the thermolysis
of 1,3λ4δ2,2,4-benzodithiadiazines affords 1,2,3-benzodithi-
azolyls for which the corresponding 1,2,3-benzodithiazoli-
ums, for example fluoro-containing ones, are unknown.[8,9]
With dilute solutions of 1,3λ4δ2,2,4-benzodithiadiazines,
the yields of radicals estimated by means of ESR measure-
ments are nearly quantitative. It is therefore of obvious
interest to investigate whether the thermolysis of
1,3λ4δ2,2,4-benzodithiadiazines can be a preparative ap-
proach to 1,2,3-benzodithiazolyls.
The present article deals with further investigation of the
solution thermolysis of 1,3λ4δ2,2,4-benzodithiadiazines in
both hydrocarbon and fluorocarbon series with special em-
phasis on concentrated solutions. It will be shown that un-
der thermolysis conditions and in concentrated hydro-
carbon solutions all the aforementioned species are seem-
ingly involved in further transformations to give complex
mixtures of products including several new and unusual
polysulfur-nitrogen heterocyclic systems. Despite very low
yields, the latter were isolated and unambiguously charac-
terized by means of X-ray diffraction. Selected spectral
properties of the new polysulfur-nitrogen heterocycles syn-
thesized, including fluorescent properties, are also reported.
Introduction
Hyperelectronic (π- and σ-excessive) 1,3λ4δ2,2,4-benzodi-
thiadiazine[1] and its carbocyclic substituted derivatives[2–5]
(Scheme 1), including polyfluorinated versions, reveal some
features of weak 12π-electron antiaromaticity[5–7] combined
with moderate thermo- and photostability.[8–11] Mild ther-
molysis[8,9,11] or photolysis[10,11] of their dilute (10–3 ) hy-
drocarbon solutions results in persistent 1,2,3-benzodithi-
azolyls (Scheme 1), which are promising building blocks in
the design and synthesis of organic molecular magnets and/
or organic molecular conductors.[12,13] The key intermedi-
ates of this transformation are R–S–N: ↔ R–SϵN nitreno-
ids (R = 1,2,3-benzodithiazol-2-yl), which can be identified
under matrix isolation conditions.[10]
Scheme 1.
The traditional synthetic approach to 1,2,3-benzodithi-
azolyls is the reduction of 1,2,3-benzodithiazolium chlorides
[a] Institute of Organic Chemistry, Russian Academy of Sciences,
630090 Novosibirsk, Russia
Results and Discussion
Fax: +7-3832-309-752
E-mail: zibarev@nioch.nsc.ru
Thermal Transformations
[b] Department of Natural Sciences, Novosibirsk State University,
630090 Novosibirsk, Russia
Under argon, the thermolysis of 0.5  solutions of
1,3λ4δ2,2,4-benzodithiadiazine (1) and its 5,6,7,8-tetra-
[c] Department of Physics, Novosibirsk State University,
630090 Novosibirsk, Russia
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DOI: 10.1002/ejic.200500383
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A. V. Zibarev et al.
FULL PAPER
fluoro derivative 2 in hydrocarbons (squalane, decane) at assigned tentatively by comparison with isomeric 12). In
150–170 °C leads to complex mixtures of various polysul- contrast to the thermolysis of 1, evolution of acidic gases
fur-nitrogen heterocycles, including previously unknown was observed.
polycyclic systems (Schemes 2 and 3). In particular, the 6-6
In both cases the major isolated products are 2,1,3-
bicyclic system of 1 and 2 transforms into differently fused benzothiadiazoles 3 and 10 (Schemes 2 and 3) as transfor-
5-5-6, 5-6-7, and 5-6-6-6 polycyclic systems. The latter are mation of 12π-electron antiaromatic compounds 1 and 2
identified for the first time. Thus, compound 1 affords 2,1,3- into 10π-electron aromatic derivatives 3 and 10 is thermo-
benzothiadiazole (3), benzopentathiepine (4), [1,2,3]dithi- dynamically attractive.
azolo[5,4-g][2λ4δ2,4,1,3,5]benzodithiatriazepine (5), and
The thermal transformations of 1 also proceed in boiling
[1,2,3]dithiazolo[4,5-c]phenothiazine (6), which were iso- 1-butanol (which does not react nucleophilically with either
lated by column chromatography of the reaction mixtures; 1 or 2) at 117 °C, i.e. at much lower temperature than in the
1,2,3-benzothiadiazole (7), benzotrithiol (8), 1,2,4λ4δ2,3,5- hydrocarbons (Scheme 4). In this case only compound 6
benzotrithiadiazepine (9), and elemental sulfur were also was isolated from the reaction mixture, which also con-
1
identified in the reaction mixtures by GLC-MS and/or H tained also small amounts of compounds 3, 4, 7, 9 and
NMR techniques (Scheme 2), and NH3 was detected in the elemental S according to the GLC-MS data.
gas phase.
Scheme 4.
Scheme 2.
In the case of 2, di-n-butyl sulfite and 2,2Ј-diamino-
3,3Ј,4,4Ј,5,5Ј,6,6Ј-octafluorodiphenyl disulfide (18) were
isolated as major products along with minor compound 11
(Scheme 4). Formation of (nBuO)2S=O (not observed in the
case of 1) can be explained by an acid-catalyzed (traces of
HF) dehydration of nBuOH, 1:1 addition of released H2O
to 2,[14] and further reaction of the addition product with
nBuOH. Compound 18 can also be considered to be a hy-
drolysis product (see ref.[3]). Thus, in this case acid-initiated
hydrolysis seemingly dominates thermal transformations.
The structures of compounds 4–6 and 11–16 were con-
firmed by X-ray crystallography (see below).
Thus, the final products of the thermal transformations
of 1,3λ4δ2,2,4-benzodithiadiazines appear to depend
strongly upon the reaction conditions employed (this work
Scheme 3.
and refs.[8,9,11]).
The thermolysis of compound 2 gives 4,5,6,7-tetrafluoro-
Formation of the same 5-6-7 and 5-6-6-6 polycyclic sys-
2,1,3-benzothiadiazole (10), 7,8-difluorobenzo[1,2-c:3,4-cЈ]- tems in both the hydrocarbon (5, 6) and fluorocarbon (13,
bis[1,2,5]thiadiazole (11), 4,5-difluorobenzo[1,2-d:4,3-dЈ]- 14) series indicates that the required carbocyclic substitu-
bis[1,2,3]dithiazole
(12),
6,7-difluoro[1,2,3]dithiazolo- tion is not electrophilic or nucleophilic in character, as is
[5,4-g][2λ4δ2,4,1,3,5]benzodithiatriazepine (13), 4,5,7,8,9,10- typical of hydrocarbon and fluorocarbon aromatics, respec-
hexafluoro[1,2,3]dithiazolo[4,5-c]phenothiazine (14), tively. Rather, we are dealing with radical and nitrenoid pro-
4,6,7,8,9,11-hexafluoro[1,2,3]dithiazolo[5,4-b]phenothiazine cesses − a conclusion which is in agreement with previous
(15), and 4,5,7-trifluoro-6-oxo-1,2,3-benzodithiazole (16), observations.[8–11] Thus, tetracyclic compounds 6, 14, and
which were isolated by column chromatography (Scheme 3). 15 can formally be considered the products of condensation
Additionally, 4,8-difluorobenzo[1,2-d:4,5-dЈ]bis[1,2,3]dithi- of the corresponding 1,2,3-benzodithiazolyls accompanied
azole (17) was detected in the reaction mixture by 19F NMR by elimination of H2S or SF2 in the hydrocarbon and fluo-
spectroscopy and GLC-MS (Scheme 3; the structure was rocarbon series, respectively (Scheme 5).
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Polysulfur-Nitrogen Heterocycles by Thermolysis
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Scheme 5.
The formation of 2,1,3- (3, 10) and 1,2,3-benzothiadi-
azoles (7) can be explained by oxidative imination of the S
atoms of 1 and 2 by R–S–N: nitrenoids followed by splitting
of the initial adducts (cf. the ability of 1,3λ4δ2,2,4-benzodi-
thiadiazines to undergo oxidative imination with SII and
PIII derivatives).[4,15] Compound 7 is known to react with
elemental sulfur to give benzopentathiepine 4, which revers-
ibly eliminates S to afford benzotrithiol 8.[16] Compound
16 could be formed by reaction of 4,5,6,7-tetrafluoro-1,2,3-
benzodithiazolyl with dioxygen.
Crystal and Molecular Structures
According to the X-ray diffraction data (Tables 2–4 and
Figures 1, 2, and 3), the polysulfur-nitrogen heterocyclic
molecules 6 and 11–16 are perfectly planar in the crystal.
The standard deviations from the mean plane are 0.039,
0.014, 0.011, 0.023, 0.064, 0.064, and 0.018 Å for 6, 11, 12,
13, 14, 15, and 16, respectively.
Generally, the crystal packing of 6 and 11–16 demon-
strates numerous shortened contacts[17,18] between the he-
teroatoms of neighboring molecules, especially S···S (4, 12,
13, 16), S···N (6, 11–13), S···O (16), S···F (12–16), and F···F
(15) contacts.
Figure 1. Molecular structures of 6, 14, and 15. Selected bond
lengths [Å] and bond angles [°]: 6: C3a–N3 1.308(3), N3–S2
1.644(2), S2–S1 2.0934(9), S1–C11b 1.747(2), S11–C10a 1.752(2),
S11–C11a 1.740(2), N6–C5a 1.312(3), C4–C5 1.342(3), C11a–C11b
1.365(3); C3a–N3–S2 116.0(2); N3–S2–S1 98.56(8), S2–S1–C11b
91.39(8). 14: C3a–N3 1.303(4), N3–S2 1.627(3), S2–S1 2.0998(19),
S1–C11b 1.747(3), S11–C10a 1.749(3), S11–C11a 1.749(3), N6–C5a
1.308(4), C4–C5 1.328(4), C11a–C11b 1.366(4); C3a–N3–S2
115.9(2), N3–S2–S1 98.57(11), S2–S1–C11b 91.50(11). 15 (averaged
over four crystallographically independent molecules): C17–S1
1.73(2), S1–S2 2.114(7), S2–N3 1.66(2), N3–C4 1.32(2), N14–C13
1.42(2), N14–C15 1.27(2), S7–C8 1.766(7), S7–C6 1.73(2); C17–S1–
S2 91.3(6), S1–S2–N3 97.9(6), S2–N3–C4 115.5(12), C13–N14–C15
119.4(12), C6–S7–C8 101.5(6).
The crystal structures of 6, 13, and 15 reveal π-stacks
with a slipped-parallel arrangement of the neighboring
molecules. The molecules of 6 and 13 are arranged in a
The structure of 5, a non-fluorinated analog of 13, was
head-to-tail fashion, whilst those of 15 are packed in a reported earlier.[20] Previously, compound 5 was obtained in
head-to-head mode. The separation between the planes of ca. 1% yield from an unsuccessful attempt to prepare the
π-stacked molecules is 3.67, 3.33–3.37, and 3.44 Å for 6, 13, benzobis(1,3λ4δ2,2,4-dithiadiazine) system.[20] The crystal
and 15, respectively (see Figures 4, 5, and 6, respectively), packing, with a π-stacked head-to-tail arrangement of
whereas their inclination varies from 0° for 15 to 2.8° for 6. neighboring molecules, features an interplanar separation
The crystal packing of 15 reveals shortened intermolecular of 3.39 Å that is closely reminiscent of that of 13 (Figure 5).
F···F contacts of 2.74–2.79 Å.
In contrast to 6, the neighboring molecules in its fluori-
In the crystal lattice of 12 (Figure 7), one of two crystal- nated analog 14 are oriented in a head-to-head manner,
lographically independent molecules is involved in S···π in- whilst their enlarged offset leads to F···π interactions rather
teractions (S···ring centroid distance: 3.46 Å) leading to co- than normal π-stacking interactions (Figure 8). The dihe-
lumnar stacks, whilst another one is involved in π–π interac- dral angle between molecular planes is 6° and the F···π sep-
tions that form dimeric pairs (interplanar separation: aration is 3.44–3.53 Å (Figure 8). As above, the different
3.51 Å). Both stacks and pairs are arranged in a head-to- orientation of the molecules for 6 and 14 can be attributed
tail fashion. For the hydrocarbon analog of 12, a slipped π- to S···N interactions in the lattice of 6 (S···N contacts: 3.10
stack structure with a head-to-head orientation of neigh- and 3.06 Å) and to S···F interactions in that of 14 (S···F
boring molecules is observed.[19]
contacts: 3.07 and 2.90 Å).
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Figure 2. Molecular structures of 11–13 and 16. Selected bond
lengths [Å] and bond angles [°]: 11: C3a–N3 1.330(2), N3–S2
1.628(2), S2–N1 1.625(2); C3a–N3–S2 106.0(1), N3–S2–N1
100.10(8), S2–N1–C8b 106.5(1). 12 (two crystallographically inde-
pendent parts of molecule): C1–S1 1.743(2), 1.741(2), S1–S2
Figure 4. Orientation of neighboring molecules in the crystal lattice
2.0944(9), 2.083(1), S2–N3 1.643(2), 1.645(2), C3–N3 1.310(3), of 6.
1.307(3); C1–S1–S2 91.04(8), 90.81(8), S1–S2–N3 99.10(8),
99.46(8), S2–N3–C3 115.2(2), 114.8(2). 13: C6–N6 1.308(4), N6–
S7 1.576(3), S7–N8 1.621(3), S9–N8 1.568(3), S9–N10 1.539(3),
C10–N10 1.350(4), C1–S1 1.700(3), S1–S2 2.055(1), S2–N3
1.614(3), C3–N3 1.304(4); C6–N6–S7 137.0(2), N6–S7–N8
117.6(1), S7–N8–S9 130.3(2), N8–S9–N10 120.8(2), C10–N10–S9
135.6(2), C1–S1–S2 91.8(1), S1–S2–N3 99.0(1), S2–N3–C3
115.3(2). 16: S1–S2 2.064(1), S2–N3 1.617(2), N3–C3a 1.314(3),
S1–C7a 1.723(2), C6–O1 1.234(3); S1–S2–N3 99.19(8), S2–N3–C3a
115.7(2), S2–S1–C7a 92.07(9), S1–C7a–C3a 113.5(2), N3–C3a–C7a
119.6(2).
Figure 3. Molecular structure of 4. Selected bond lengths [Å] and
bond angles [°] (averaged over two crystallographically independent
molecules): C10–S1 1.806(9), S1–S2 2.044(4), S2–S3 2.050(4), S3–
S4 2.043(4), S4–S5 2.041(4), S5–C11 1.808(10); C11–C10–S1
123.2(8), C10–S1–S2 103.6(3), S1–S2–S3 104.1(1), S2–S3–S4
102.5(1), S3–S4–S5 104.3(2), S4–S5–C11 103.5(3), S5–C11–C10
122.7(7).
The crystal packing of 11 and 16 reveals a typical her-
ringbone pattern. In contrast to 11, columnar π-stacks and
molecular layers are formed in the crystal structure of its
non-fluorinated analog. Additionally, shortened S···N con-
tacts give rise to a ribbon-like quasi-polymeric structure.[21]
For compound 4, which was structurally defined pre-
viously[22] (see ref.[16] for derivatives), a new polymorph is
observed. The hetero rings of two crystallographically inde-
pendent molecules have the chair-twist-chair (TC) confor- of 13.
Figure 5. Orientation of neighboring molecules in the crystal lattice
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Figure 8. Orientation of neighboring molecules in the crystal lattice
of 14.
mation with C2 symmetry. The molecules are involved in π-
stacking interactions with a separation of 3.52–3.57 Å be-
tween neighboring benzene rings (Figure 9). Overall, the
stacks form a layered structure.
Figure 6. Orientation of neighboring molecules in the crystal lattice
of 15.
Figure 7. Orientation of neighboring molecules in the crystal lattice
of 12.
Figure 9. Orientation of neighboring molecules in the crystal lattice
of 4.
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In the previously observed crystal lattice,[22] π-stacked di- Alternative Approaches to 5-6-6-6 Systems
mers can be identified (separation of benzene rings: 3.41 Å)
Due to the potential of the 5-6-6-6 systems as fluorescent
dyes, rational approaches to their preparation are of inter-
est. These can probably be designed based on phenothiazine
systems in both the hydrocarbon and fluorocarbon series.
Meanwhile, it was found that compound 15, the most
interesting in the context of OLEDs, can be obtained in
moderate yield as the final product of a spontaneous trans-
formation of R–N=PPh3 (19; R = 4,5,6,7-tetrafluoro-1,2,3-
that are combined into stacks by S···π interactions (ring
centroid···S atom distance: 3.48 Å). Overall, the stacks form
a herringbone structure.[22]
Selected Spectral Properties
For 1 and its carbocyclic substituted derivatives, the max-
ima of the weak (log ε Ϸ 2.4–2.8) long-wavelength absorp-
tions in the UV/Vis spectra are in the range of ca. 610–
635 nm.[1–5] The 5-5-6 (12 and its hydrocarbon analog[19]),
5-6-7 (5, 13), and angular 5-6-6-6 (6, 14) systems reveal
strong (log ε Ϸ 3.9–4.2) absorptions in about the same
range of ca. 570–635 nm, whereas the linear 5-6-6-6 system
15 absorbs at shorter wavelengths (Table 1), with only a
weak dependence of the corresponding πǞπ* transitions
in extended polyheteroatom π-systems upon substitution of
fluorine for hydrogen. Additionally, the 5-6-6-6 systems (6,
14, 15) demonstrate strong fluorescence in the range of ca.
660–680 nm (Table 1). The Stokes shifts are very different
for angular (ca. 40–60 nm for 6, 14) and linear (ca. 140 nm
for 15) derivatives (Table 1). Taking into account the solu-
bility of the discussed compounds in organic solvents, their
thermal stability, and their stability towards moisture (in
sharp contrast to starting 1,3λ4δ2,2,4-benzodithiadiaz-
benzodithiazol-2-yl) in CHCl3 solution (Scheme 6). The 19
F
and 31P NMR spectra of the reaction mixture reveal forma-
19F
31P
tion of Ph3PF2 [δ = 121.9 ppm (d, JF,P = 660 Hz); δ
= –54.5 ppm (t, JP,F = 660 Hz); cf. ref.[24]] and, tentatively,
Ph3P=N–H [δ = 22.0 (s); cf. ref.[25]] as by-products. At
31P
[27]
the same time, Ph3P=S[26] and (SN)4 are not observed in
the 31P and 14N NMR spectra, respectively. The reaction is
solvent-dependent and does not proceed, for example, in
toluene.
Scheme 6.
We found by ESR spectroscopy that in CHCl3 solution
ines),[3,14] it is possible to believe that the polysulfur-nitro- (but not in toluene) and at ambient temperature, compound
gen heterocycles synthesized here can be considered as po- 19 spontaneously produces 1,2,3-benzodithiazolyl (20;
tential fluorescent dyes. Furthermore, the spectral proper- Scheme 7; see refs.[8,9] for the ESR spectrum), seemingly by
ties of compound 15 are very similar to those of novel non- reversible homolytic splitting of the exocyclic S–N bond. At
doping organic light-emitting diodes (OLEDs).[23]
the same time, the second product of such splitting − the
Table 1. Spectroscopic data for compounds 5, 6, and 11–16.
NMR, δ [ppm]
UV/Vis
λmax [nm] (log ε)
Fluorescence
λmax/λexit. [nm]
1H
19F[a]
13C
14N
5
6
7.60 (d)[b], 7.11 (d)[b]
625 (4.0), 582 (4.0)[20]
7.48 (d, 1 H), 7.41 (d,
1 H), 7.23 (m, 2 H),
7.18 (td, 1 H), 7.14
(ddd, 1 H)
610 (4.02), 579 (4.02), 337 (4.15),
253 (4.23)
667/330
11
12
13
14
15.8
148.2, 144.6, 142.3 334
149.6, 142.8, 123.7 295
315 (3.89; sh.), 286 (4.44)
17.9
589 (4.23), 340 (4.17), 234 (3.84)[c]
635 (3.95), 587 (4.02), 363 (4.09)
31.3, 0.8[d]
23.9, 20.7, 19.4,
17.3, 8.7, 4.8
148.8, 145.2,
144.9, 143.8,
143.5, 141.9,
140.1, 132.5,
126.3, 105.7, 103.4
615 (3.88; sh.), 585 (3.90), 394
(3.70), 349 (3.92), 255 (4.10)
657/340
675/335
15
16
42.0, 40.9, 18.8,
16.5, 7.4, 4.5
533 (4.68), 268 (4.70), 235 (4.49)
482 (3.97), 348 (3.80), 253 (3.47)
32.8, 20.6, 17.8[d]
[a] C6F6 as standard; the chemical shift of C6F6 with respect to CFCl3 is –162.2 ppm. [b] J = 10 Hz. [c] Cf. Hydrocarbon analog (in
CH2Cl2): 572 (4.2), 329 (4.0).[19] [d] In [D8]toluene.
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Ph3P=N· radical − was not observed, very likely due to fast
decay by hydrogen abstraction from the CHCl3 solvent.
Thus, the equilibrium shown in Scheme 7 might be shifted
towards radical 20 and an explanation of the self-condensa-
tion of 19 into 15 can be suggested, including the role of
the CHCl3 solvent (Scheme 7).
Experimental Section
General: Compounds 1[1] and 2[2] were prepared by known meth-
ods. Their thermolysis was carried out under argon in absolute sol-
vents, with stirring. The concentration of residual water in nBuOH
was controlled by gas chromatography to be 0.02 . The chromato-
graphic separations of the products were performed with silica col-
umns. The physical and analytical data for the compounds synthe-
sized are listed in Tables 4 and 5. Compound 19[15] was prepared
in 60% yield by an improved procedure, the details of which will
be given elsewhere.[30]
The 1H, 13C, 14N, and 31P NMR spectra were measured with a
Bruker DRX-500 spectrometer at frequencies of 500.13, 125.76,
36.13, and 202.46 MHz, respectively, with TMS, NH3 (liq.) and
85% H3PO4 as standards; the 19F NMR spectra were recorded with
a Bruker AC-200 machine at a frequency of 188.28 MHz with C6F6
as the standard; solutions in CDCl3 were used unless otherwise
indicated.
The high-resolution mass spectra (EI, 70 eV) were recorded with a
Finnigan MAT MS-8200 instrument.
The UV/Vis spectra were recorded on Specord M40 and Hewlett–
Packard 8453 spectrophotometers for solutions in CHCl3. The flu-
orescent spectra were measured with a Kontron SFM-25 spectro-
fluorimeter for MeCN solutions.
Scheme 7.
The GLC-MS determinations were performed with a Hewlett–
Packard G1800A GDC apparatus. The GC measurements were
carried out with a Hewlett–Packard 5890 instrument.
A postulated SN· by-product (Scheme 7) is very unstable
and undetectable by ESR spectroscopy in the condensed
phase due to strong g-anisotropy (see ref.[28] and references
therein).
The ESR measurements were carried out on a Bruker ESP-300
spectrometer (MW power: 265 mW; modulation frequency: 100
kHz; modulation amplitude: 0.005 mT) for a CHCl3 solution of 19.
The spectral integration and simulation were performed with the
Winsim 32 program.
Crystallographic Analysis: The single-crystal structure determi-
nations (Tables 2, 3, and 4) were carried out on Bruker P4 (4–6,
11–14, 16) and Syntex P21 (15) diffractometers with graphite-mo-
nochromated Mo-Kα (λ = 0.71073 Å) and Cu-Kα (λ = 1.54178 Å)
radiation, respectively. The structures were solved by direct meth-
ods by use of the SHELXS-97 program[31] and refined by the least-
squares method in the full-matrix anisotropic (isotropic for H
atoms) approximation by use of the SHELXL-97 program.[31] Hy-
drogen atoms were located geometrically. The structures obtained
were analyzed for shortened contacts between non-bonded atoms
with the PLATON program.[32,33]
For compounds 4 and 15, available single crystals were very small
(Tables 2 and 4) and reflections could only be measured to θ =
22.5° and θ = 57°, respectively. The structure of 15 was refined with
AFIX and EADP restraints applied to selected geometrical and
anisotropic parameters, respectively: the C6F4 moiety was re-
strained to be a right hexagon with all C–F bond distances of
1.35 Å, for each C–F bond of the molecule thermal parameters of
the F atom were fixed at corresponding values of the C atom.
CCDC-268796 (for 4), -268797 (for 6), -268798 (for 11), -268799
(for 12), -268800 (for 13), -268801 (for 14), -268802 (for 15), and
-268803 (for 16) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. For 5, the data obtained in this work are in full
agreement with those published previously.[20]
Conclusions
In contrast to thermolysis in dilute solutions, which leads
to persistent 1,2,3-benzodithiazolyls (which are promising
building blocks in the design and synthesis of organic mol-
ecular magnets and/or organic molecular conductors) in ne-
arly quantitative yields, the thermal transformations of
1,3λ4δ2,2,4-benzodithiadiazines 1 and 2 (the 6-6 bicyclic
system) in concentrated solutions results in complex mix-
tures of various polysulfur-nitrogen heterocycles, in particu-
lar differently fused 5-5-6, 5-6-7, and 5-6-6-6 polycyclic sys-
tems that were previously unknown. Despite very low
yields, the products were isolated and unambiguously iden-
tified by X-ray diffraction. The polycyclic π-functional
molecules prepared engage in anisotropic intermolecular in-
teractions in the solid state and are therefore of interest for
materials science.[29] In both hydrocarbon and fluorocarbon
series, the polycyclic systems synthesized demonstrate
strong long-wavelength absorption and fluorescence and
can be considered as potential fluorescent dyes. All the
aforementioned properties motivate the elaboration of ra-
tional approaches to the discussed compounds, and this can
be a direction for further investigations in this field. The
transformation of the R–N=PPh3 derivative 19 (R =
4,5,6,7-tetrafluoro-1,2,3-benzodithiazol-2-yl) into the 5-6-6-
6 system 15, which was discovered and explained in the
present work, can be considered promising in this context.
Identification of Known Compounds: The isolated compounds 3,[34]
5,[20] 10,[35] and 18,[3] described previously, were identified by com-
parison of reported m.p.’s, unit cell (XRD) and spectral (1H and
Eur. J. Inorg. Chem. 2005, 4099–4108
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A. V. Zibarev et al.
FULL PAPER
Table 2. Crystal data and structure refinement for compounds 4, 6, and 11.
Compound
4
6
11
Empirical formula
Formula mass
Temperature [K]
Crystal system
Space group
a [Å]
C6H4S5
236.39
298(2)
monoclinic
P21/c
7.729(1)
9.457(1)
25.453(3)
C12H6N2S3
274.37
296(2)
monoclinic
C2/c
12.9236(7)
12.8240(8)
15.214(1)
C6F2N4S2
230.22
296(2)
orthorhombic
Pnma
9.2356(6)
b [Å]
c [Å]
16.856(1)
5.1668(4)
β [°]
95.06(1)
1853.3(4)
8
1.694
1.179
0.20×0.15×0.05
2.30–22.50
–8 Յ h Յ 0
0 Յ k Յ 10
–27 Յ l Յ 27
2627
114.964(5)
2285.9(3)
8
1.594
0.622
0.70×0.20×0.15
2.35–25.00
0 Յ h Յ 15
–15 Յ k Յ 0
–18 Յ l Յ 16
2096
90
804.33(9)
4
1.901
0.654
0.80×0.34×0.05
2.42–30.00
–12 Յ h Յ 0
0 Յ k Յ 23
–7 Յ l Յ 0
1212
Volume [Å3]
Z
Dcalcd. [Mgm–3]
Absorption coefficient [mm–1]
Crystal size [mm3]
θ range for data collection [°]
Index ranges
Reflections collected
Independent reflections
Completeness to θ [%]
Absorption correction
Min. and max. transmission
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
2417 [R(int) = 0.0466]
99.8
empirical
0.73 and 0.88
2417/0/199
0.885
R1 = 0.0572, wR2 = 0.1319
R1 = 0.1163, wR2 = 0.1487
2017 [R(int) = 0.0205]
100.0
empirical
0.96 and 0.99
2017/0/154
1.062
R1 = 0.0329, wR2 = 0.0843
R1 = 0.0420, wR2 = 0.0894
1212 [R(int) = 0.0]
100.0
integration
0.78 and 0.97
1212/0/64
1.044
R1 = 0.0381, wR2 = 0.0923
R1 = 0.0616, wR2 = 0.1033
Table 3. Crystal data and structure refinement for compounds 12–14.
Compound
12
13
14
Empirical formula
Formula mass
Temperature [K]
Crystal system
Space group
a [Å]
C6F2N2S4
266.32
296(2)
monoclinic
C2/m
7.818(2)
C6F2N4S4
294.34
296(2)
monoclinic
P21/c
8.513(3)
C12F6N2S3
382.32
296(2)
monoclinic
P21/n
7.292(6)
b [Å]
23.204(5)
16.677(6)
4.700(4)
c [Å]
10.124(2)
102.45(1)
1793.4(6)
8
1.973
1.043
0.80×0.28×0.20
2.06–27.50
0 Յ h Յ 9
0 Յ k Յ 30
–13 Յ l Յ 12
2243
6.690(2)
97.71(1)
941.2(6)
4
2.077
1.011
0.70×0.34×0.10
2.41–27.51
–10 Յ h Յ 11
–21 Յ k Յ 0
–8 Յ l Յ 0
2337
37.29(3)
94.27(5)
1274.7(19)
4
1.992
β [°]
Volume [Å3]
Z
Dcalcd. [Mgm–3]
Absorption coefficient [mm–1]
Crystal size [mm3]
θ range for data collection [°]
Index ranges
0.653
0.90×0.44×0.02
2.19–25.00
0 Յ h Յ 8
0 Յ k Յ 5
–44 Յ l Յ 44
2421
Reflections collected
Independent reflections
Completeness to θ [%]
Absorption correction
Min. and max. transmission
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
2094 [R(int) = 0.0323]
98.7
integration
0.77 and 0.84
2094/0/128
1.036
2158 [R(int) = 0.0822]
99.9
integration
0.72 and 0.91
2158/0/145
1.049
2229 [R(int) = 0.0348]
98.8
integration
0.84 and 0.99
2229/0/208
1.038
R1 = 0.0383, wR2 = 0.1039
R1 = 0.0412, wR2 = 0.1061
R1 = 0.0546, wR2 = 0.1451
R1 = 0.0653, wR2 = 0.1551
R1 = 0.0383, wR2 = 0.0974
R1 = 0.0563, wR2 = 0.1068
19F NMR, UV/Vis, MS) parameters with those obtained in this
work. Di-n-butyl sulfite was identified by GLC-MS. Compounds
7,[34] 8,[16] and 9[36] were identified without isolation by means of
GLC-MS and 1H NMR techniques by comparison with the au-
thentic samples.
See Table 5 for spectroscopic data for compounds 5, 6, and 11–16.
Thermolysis of 1,3λ4δ2,2,4-Benzodithiadiazine (1) in Squalane. For-
mation of Compounds 3–6: A solution of 0.34 g (2 mmol) of 1 in
3 mL of squalane was stirred at 150–160 °C for 3 h, cooled to
4106
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2005, 4099–4108

Polysulfur-Nitrogen Heterocycles by Thermolysis
FULL PAPER
Table 4. Crystal data and structure refinement for compounds 15 and 16.
Compound
15
16
Empirical formula
Formula mass
Temperature [K]
Crystal system
Space group
a [Å]
C12F6N2S3
382.32
296(2)
monoclinic
Cc
11.310(2)
11.311(2)
39.884(8)
97.97(2)
5052.7(18)
16
C6F3NOS2
223.19
296(2)
monoclinic
P21/n
5.1828(7)
9.706(1)
14.298(2)
95.85(1)
715.5(2)
4
b [Å]
c [Å]
β [°]
Volume [Å3]
Z
Dcalcd. [Mgm–3]
Absorption coefficient [mm–1]
Crystal size [mm3]
θ range for data collection [°]
Index ranges
2.010
6.119
2.072
0.749
0.13×0.13×0.03
2.24–57.43
0 Յ h Յ 12
0 Յ k Յ 12
–43 Յ l Յ 43
4151
0.80×0.20×0.08
2.54–24.99
–6 Յ h Յ 0
0 Յ k Յ 11
–16 Յ l Յ 16
1398
Reflections collected
Independent reflections
Completeness to θ [%]
Absorption correction
Min. and max. transmission
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
3688 [R(int) = 0.1374]
100.0
empirical
0.46 and 0.82
3688/38/544
1.051
R1 = 0.0739, wR2 = 0.1679
R1 = 0.1311, wR2 = 0.2071
1250 [R(int) = 0.0186]
99.9
empirical
0.87 and 0.98
1250/0/118
1.065
R1 = 0.0329, wR2 = 0.0939
R1 = 0.0387, wR2 = 0.0980
pound 10[35] (36 mg; 5%) was obtained as colorless crystals. The
reaction precipitate was sublimed at 170 °C/2 mm and the subli-
mate chromatographed. Elution with toluene gave blue and red
zones. Sublimation of the product from the blue zone at 110 °C/
2 mm gave a mixture of 12, 14, and 17. Compound 14 (6 mg) was
obtained as black crystals by further chromatography of this mix-
ture (1:1 hexane/toluene) followed by crystallization from hexane.
Compound 12 (3 mg) was obtained as black crystals by crystalli-
zation of its mixture with isomeric 17 from 4:1 hexane/toluene. The
mother liquor contained residual 12 (GLC-MS: m/z = 226 [M+];
19F NMR: δ = 17.9 ppm) and 17 (GLC-MS: m/z = 226 [M+]; 19F
NMR: δ = 40.7 ppm; the structure was assigned tentatively).
Crystallization (toluene) of the non-volatile residue from sublima-
tion gave 13 (3 mg) as black crystals. Sublimation of the product
from the red zone at 120 °C/2 mm gave 15 (1 mg) as black crystals.
Elution with 10:1 toluene/ethyl acetate gave 11 and 16, which were
purified by sublimation at 120 °C/2 mm. Compound 11 (12 mg)
Table 5. Characterization of compounds 5, 6, and 11–16.
MS: M+ (m/z) measured (calcu-
lated)
M.p. [°C] Formula
5
269–271
206–208
C6H4N4S4 257.9154 (257.9162)
C12H6N2S3 273.9724 (273.9693)
6
11
12
13
14
15[b]
16
175–176[a] C6F2N4S2
230–232[a] C6F2N2S4
280–282[a] C6F2N4S4
229.9542 (229.9533)
265.8918 (265.8912)
293.8972 (293.8974)
216–217
234–236
210–212
C12F6N2S3 381.9133 (381.9128)
C12F6N2S3 381.9152 (381.9128)
C6F3NOS2 222.9371 (222.9374)
[a] In a sealed capillary. [b] Correct elemental analyses for C, F, N,
S.
20 °C, filtered and chromatographed. Elution with hexane gave
1
50 mg of a red oil consisting (GLC-MS, H NMR) of compounds
9 (33%), 4 (31%), 8 (13%), 3 (3%), 7 (1.5%), elemental S (0.6%), was obtained as colorless crystals and compound 16 (6 mg) as
and squalane (5%). Compound 4 (5 mg) was isolated by low-tem-
perature crystallization from hexane as pale-yellow crystals (m.p.
55–56 °C). Elution with toluene gave 30 mg (10% yield) of com-
pound 3[34] as colorless crystals. Elution with 1:1 CH2Cl2/ethyl ace-
tate followed by crystallization of the product from 10:1 hexane/
toluene gave compound 6 (4 mg) as black crystals. The reaction
precipitate was refluxed in toluene and the solution formed was
chromatographed. Elution with toluene followed by recrystalli-
zation of the product from the same solvent gave compound 5
(2 mg) as black crystals. The gases evolved during the thermolysis
were absorbed by dilute HCl. Photometrical analysis with Nessler’s
reagent revealed NH3 in 3% yield.
black crystals.
Thermolysis of Compound 1 in 1-Butanol. Formation of Compound
6: A solution of 0.17 g (1 mmol) of 1 in 1 mL of nBuOH was re-
fluxed for 3.5 h, cooled to 20 °C and chromatographed. Elution
with CH2Cl2 gave ca. 4 mg of a mixture (GLC-MS data) of com-
pounds 3 (20%), 4 (traces), 7 (40%), 9 (20%), and elemental S
(20%). Elution with 10:1 CH2Cl2/ethyl acetate gave compound 6.
The latter was repeatedly chromatographed under the same condi-
tions and recrystallized from 10:1 hexane/toluene to give black
crystals (1 mg).
Thermolysis of Compound 2 in 1-Butanol. Formation of Compounds
11 and 18: A solution of 0.48 g (2 mmol) of 2 in 2 mL of nBuOH
was refluxed for 4 h, cooled to 20 °C, and chromatographed (hex-
ane) to give ca. 0.17 g of di-n-butyl sulfite, compound 11, and com-
pound 18. Compound 11 (4 mg) was obtained as colorless crystals
Thermolysis of 5,6,7,8-Tetrafluoro-1,3λ4δ2,2,4-benzodithiadiazine
(2) in Decane. Formation of Compounds 10–16: A solution of 0.96 g
(4 mmol) of 2 in 8 mL of decane was stirred at 160–170 °C for 6 h,
cooled to 20 °C, filtered and chromatographed (hexane). Com-
Eur. J. Inorg. Chem. 2005, 4099–4108
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A. V. Zibarev et al.
FULL PAPER
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by sublimation at 120 °C/2 mm followed by recrystallyzation from
hexane. Compound 18[3] (54 mg) was obtained as yellow crystals
by sublimation at 130 °C/2 mm followed by recrystallization from
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Received: April 29, 2005
Published Online: September 8, 2005
4108
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2005, 4099–4108