Generation and selected reactions of chlorinated thiocarbonyl S-imides*

Article abstract of DOI:10.1080/17415993.2017.1325892

N-Aryl-1,1,1-trichloromethanesulfenamides ArNH-SCCl₃ easily undergo dehydrochlorination upon treatment with potassium hydroxide in ethanolic solution. The intermediate thiocarbonyl S-imides formed thereby behave differently depending on the typ

Full text of DOI:10.1080/17415993.2017.1325892

Journal of Sulfur Chemistry
ISSN: 1741-5993 (Print) 1741-6000 (Online) Journal homepage: http://www.tandfonline.com/loi/gsrp20
Generation and selected reactions of chlorinated
thiocarbonyl S-imides
Grzegorz Mlostoń, Paulina Pipiak, Jürgen Voss, Dirk Buddensiek & Alexander
Senning
To cite this article: Grzegorz Mlostoń, Paulina Pipiak, Jürgen Voss, Dirk Buddensiek & Alexander
Senning (2017): Generation and selected reactions of chlorinated thiocarbonyl S-imides, Journal of
Sulfur Chemistry, DOI: 10.1080/17415993.2017.1325892
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Date: 20 May 2017, At: 00:41

JOURNAL OF SULFUR CHEMISTRY, 2017
https://doi.org/10.1080/17415993.2017.1325892
Generation and selected reactions of chlorinated
thiocarbonyl S-imides∗
Grzegorz Mlostońa, Paulina Pipiaka, Jürgen Vossb, Dirk Buddensiekb and
Alexander Senningc†
aDepartment of Organic and Applied Chemistry, University of Łódź, Łódź, Poland; bDepartment of Chemistry,
University of Hamburg, Hamburg, Germany; cDepartment of Chemistry, Technical University of Denmark,
Lyngby, Denmark
ABSTRACT
ARTICLE HISTORY
Received 15 February 2017
Accepted 27 April 2017
N-Aryl-1,1,1-trichloromethanesulfenamidesArNH-SCCl3 easilyundergo
dehydrochlorination upon treatment with potassium hydroxide in
ethanolic solution. The intermediate thiocarbonyl S-imides formed
thereby behave differently depending on the type of the N-
aryl group. The sterically crowded N-(2,6-dimethylphenyl)- and -
N-(2,4,6-trimethylphenyl)-1,1,1-trichloromethanesulfenamides yield
the corresponding sulfur N,Nꢀ-diaryldiimides via a multi-step reac-
tion, whereas the less crowded 2-methylphenyl and 4-methylphenyl
derivatives undergo a regioselective ‘head-to-head’ dimerization
leading to 5,5,6,6-tetrachloro-1,4,2,3-dithiadiazinanes in high yields.
An identical reaction course is observed in the case of the 4-methoxy-
and 4-bromoaniline derivatives. A diradical mechanism is postulated
to explain the ‘head-to-head’ dimerization pathway.
KEYWORDS
Thiocarbonyl compounds;
reactive intermediates;
thiocarbonyl S-imides;
chlorinated organic
compounds; head-to-head
dimerization
Me
Me
S
Me
Cl
Cl
R = Me
N
N
S
S
Me
R = H
Cl2C
Cl2C
N
N
C
S
2
N
Me
Me
- C2Cl4S
Me
R
thiocarbonyl S-imide
1. Introduction
Thiocarbonyl S-imides 1 belong to the class of so-called ‘S-centered’ 1,3-dipoles (struc-
tures 1A–B), which can also be presented either as mesomeric nonlinear heterocumulenes
1C or as diradicals 1D (Figure 1) [1]. They are known to react with dipolarophiles yield-
ing the expected five-membered cycloadducts or with 1,3-dienes to give six-membered
=
hetero-Diels-Alder products, formed upon the involvement of the C S bond as the hetero-
dienophile [2,3]. In the absence of a suitable dipolarophile or 1,3-diene, they undergo either
CONTACT Grzegorz Mlostoń
gmloston@uni.lodz.pl
Department of Organic and Applied Chemistry, University
of Łódź, Tamka 12, PL-91-403 Łódź, Poland
*Dedicated to Professor Heinz Heimgartner on the occasion of his 75th birthday.
‡Retired.
© 2017 Informa UK Limited, trading as Taylor & Francis Group

2
G. MLOSTOŃ ET AL.
R1
R2
R1
R1
R2
R1
R2
C
S
C
S
C
S
C
S
NR3
R2
NR3
NR3
NR3
1A
1B
1C
1D
Figure 1. Mesomeric structural formulae of thiocarbonyl S-imides 1.
Scheme 1. Synthesis of thiocarbonyl S-imides 1.
1,3-dipolar electrocyclization yielding thiaziridines, or alternatively undergo dimerization
to give six-membered dithiadiazinanes. These dimerizations could occur either as head-
to-head (1,4,2,3-dithiadiazinane) or as head-to-tail (1,4,2,5-dithiadiazinane) processes
[2–4].
The most important methods applied for the preparation of isolable 1 are imination
of thiocarbonyl compounds 2 or dehydrochlorination of α-chloroalkanesulfenamides 3
(Scheme 1) [2,3]. In addition, thiocarbonyl S-imides 1 can be generated in situ as reac-
tive intermediates in reactions of thioketones 4 with organic azides as well as in some
instances, via dehydrochlorination of suitable sulfenamides 3, for example in the case of
2
N-substituted trichloromethanesulfenamides 3 (R1
R
Cl) [3,4].
=
=
First experiments aimed at the dehydrochlorination of N-arylsulfenamides 3 have been
already reported in 1886 by Rathke, who suggested the structure of a thiaziridine derivative
for the isolated products [5]. In another report, the same products were suggested to pos-
sess the structure of a 1,4,2,5-dithiadiazinane formed via head-to-tail dimerization of the
intermediate 1 [6]. Finally, the correct structure of the product 7a, that is the head-to-head
dimer, was reported by Potts, who elucidated it by means of an X-ray diffraction analy-
sis [7]. The mechanism of the head-to-head versus head-to-tail dimerization has recently
been investigated by a computational study [8].
The aim of the present study was to examine the reactivity of thiocarbonyl S-arylimides,
such as thiophosgene S-imides 6a–d and trichlorothioacetyl chlorideS-imides 6e–f includ-
ing sterically crowded thiocarbonyl S-arylimides with 2,6-disubstituted aryl groups. An
important question was if the expected dimerization occurs with complete or partial

JOURNAL OF SULFUR CHEMISTRY
3
1
−
=
Scheme 2. Synthesis of sulfenamides 3a k from sulfenyl chlorides (R Cl or CCl3) and primary amines
5a–h.
−
Table 1. Synthesis of sulfenamides 3a k from sulfenyl chlorides and primary amines 5a–h.
3
R1
R2
Yield [%]
Ref.
a
b
c
d
e
f
g
h
ia
j
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
4-MeC6H4
2-MeC6H4
4-BrC6H4
4-MeOC6H4
2,6-Me2C6H3
2,4,6-Me3C6H2
i-Pr
93
87
90
87
73
88
50
90
–
[6,7]
[5]
[9]
[6]
−
−
[10]
[11]
−
t-Bu
Cl
CCl3
CCl3
2,4,6-t-Bu3C6H2
4-MeC6H4
2,4,6-Me3C6H2
80
95
−
k
−
aCould not be obtained.
regioselectivity leading either to only one head-to-head or alternatively, head-to-tail, dimer
or rather to a mixture of both products. In addition, the postulated formation of an
aryl isothiocyanate via the dehydrochlorination of sterically crowded 2,6-dimethylphenyl
substituted sulfenamide 3e, followed by steam distillation, should be reexamined [6].
2. Results and discussion
The starting sulfenamides 3 were prepared by the treatment of the corresponding pri-
mary amines 5a–i with trichloromethanesulfenyl chloride or pentachloroethanesulfenyl
chloride, respectively (see Scheme 2 and Table 1). Only in the case of the extremely
crowded 2,4,6-tri(tert-butyl)aniline (5i), no reaction was observed even after 24 h at room
temperature.
Solutions of the sulfenamides 3 in ether were treated with ethanolic potassium hydrox-
ide solution at room temperature to achieve the required dehydrochlorination. The crude
reaction products of 3 were examined by 1H NMR spectroscopy. The characteristic NH
−
signals of 3a f at ca. 6 ppm disappeared during all reactions. The crystalline compounds
7a–d were isolated from the product mixtures obtained by dehydrochlorination of 3a d
(Scheme 3).
−
The presence of only one compound in the crude product was evidenced by the obser-
vation of only one set of the expected NMR signals. The products were purified by column
chromatography and the structures of type 7 were elucidated by 1H and 13C NMR spec-
troscopy. For example, 7a exhibited one 1H signal at 2.34 ppm which was attributed to the
two equivalent methyl groups. The corresponding 13C signal appeared at 20.5 ppm and

4
G. MLOSTOŃ ET AL.
−
Scheme 3. Formation of 1,4,2,3-dithiadiazinanes 7a–d by dehydrochlorination of sulfenamides 3a d.
Figure 2. ORTEP plots of the molecular structures of 7a (left) and 7c (right) drawn with 50% probability
displacement ellipsoids.
the signal for two CCl2 groups was found at 93.3 ppm. The melting point of 7a was in
agreement with the one reported by Potts [7].
Since Potts’s X-ray diffraction analysis is not well documented [7] we raised doubts
−
in our previous publication [8] on his reported C C bond length of 177.1 pm in the
1,4,2,3-dithiadiazinane 7a. Therefore, we performed a new low-temperature X-ray struc-
ture analysis of this compound. The result is shown in Figure 2 and compiled in Table 2.
−
Expectedly, we found d(C5 C6) to be 155.0 pm in perfect agreement with our MO the-
oretical value of 155.3 pm. Furthermore, the C Cl bond lengths turned out to be ca. 178
−
pm as we had suspected [8].
The structure of the head-to-head dimer was also established for 7c based on another
X-ray diffraction analysis (Figure 2). Interestingly, in the case of the 4-methoxyphenyl
derivative 7d, the initially isolated colorless crystalline material, expected to be the analo-
gous head-to-head dimer, underwent slow decomposition in CDCl3 solution and changed
the color to deep red. The 1H NMR spectrum registered after 24 h at room temperature
evidenced the presence of a complex mixture of non-identifiable products. In our opinion,
7d may undergo a slow decomposition, likely via the monomeric thiocarbonyl S-imide 6d,
which is expected to be an orange-red species [1]. Dehydrochlorination of 3b led to the
expected head-to-head dimer 7b. Its structure was confirmed by the 13C NMR data, that
is comparison of the chemical shifts of the CCl2 signals of 7a (93.3 ppm), 7b (94.1 ppm),
7c (92.9 ppm), and 7d (93.0 ppm), respectively. The 1,4,2,3-dithiadiazinanes 7a–c are sta-
ble compounds with no tendency to undergo decomposition in CDCl3 solution at room
temperature.

JOURNAL OF SULFUR CHEMISTRY
5
=
=
Table 2. Bond lengths (pm), bond angles (°), and torsion angles (°) of 7a (R Me) and 7c (R Br).
X-ray (7a) [7]
PM7 (7a) [8]
X-ray (7a)
DFT (7a)a
X-ray (7c)
Bond lengths
−
N2 N3
141.3
170.3
168.6
183.3
177.1
182.1
139
179
179
186
151
186
140.8
170.0
169.7
183.0
155.0
182.4
177.5
178.1
178.1
177.3
135.7
170.7
174.6
185.3
155.3
183.8
178.7
179.2
179.1
179.1
141.0
169.8
169.6
183.0
155.6
183.1
177.4
177.9
177.0
177.2
189.7
190.1
−
S1 N2
−
N3 S4
−
S1 C6
−
C5 C6
−
S4 C5
−
C5 Cl51
−
C5 Cl52
−
C6 Cl61
−
C6 Cl62
−
C24 Br
−
C34 Br
Bond angles
−
−
N2 S1 C6
101.2
114.9
110.5
110.5
114.7
102.7
102.9
113.8
111.9
111.9
113.9
102.8
101.7
115.2
110.8
110.2
114.9
101.9
101.0
113.3
114.0
111.8
116.5
101.9
101.7
114.8
110.4
110.2
115.6
101.5
−
−
N2 N3 S4
−
−
S4 C5 C6
−
−
S1 C6 C5
−
−
S1 N2 N3
−
−
N3 S4 C5
Torsion angles
−
− −
N2 S1 C6 C5
58.0
−62.2
57.6
−18.8
61.3
−40.3
−27.2
79.1
−
− −
S1 C6 C5 S4
−
− −
C6 C5 S4 N3
−
−
−
C5 S4 N3 N2
−59.8
−
−
−
S4 N3 N2 S1
68.6
−
− −
N3 N2 S1 C6
−60.4
−52.6
−
−
−
C
N3 N2
C
117.3
aB3LYP1-D with dispersion correction.
A different pathway of the dehydrochlorination was observed when the sterically
2
crowded sulfenamides 3e (R2 2,6-Me2C6H3) and 3f (R 2,4,6-Me3C6H2) were used as
precursors of the expected thiocarbonyl S-imides 6. Thus, in the case of 3e, the only prod-
uct isolated as orange crystals after chromatographic work up did not show the expected
signal of the CCl2 groups in the 13C NMR spectrum. Instead, the signals of Me groups
located at 18.9 ppm, CHarom at 124.8 ppm, and 127.4 ppm, as well as Cq,arom at 128.4 and
142.4 ppm, evidenced the presence of the 2,6-dimethylphenyl group. The elemental analy-
sis confirmed the molecular formula C16H18N2S. In addition, the IR spectrum showed two
strong absorption bands located at 1280 and 1242 cm−1, respectively. Based on these data,
the structure of the product was formulated as sulfur N,Nꢀ-bis(2,6-dimethylphenyl)diimide
(8a) (Scheme 4) which we finally confirmed by an X-ray structure analysis (see Table 1
and Figure 4). It turned out that previously Zibarev et al. [12] had prepared 8a by treat-
ment of 5e with sulfur tetrafluoride SF4 and our X-ray structure analysis is identical with
=
=

6
G. MLOSTOŃ ET AL.
ꢀ
−
Scheme 3. FormationofsulfurN,N -diaryldiimides8a–bviadehydrochlorinationofsulfenamides3e f.
Scheme 4. ORTEP Plot of the molecular structure of 8a, drawn with 50% probability displacement
ellipsoids.
the reported result. Interestingly, product 8a, like other sulfur N,Nꢀ-diaryldiimides bearing
bulky substituents [12], exhibits the sterically crowded Z,Z-configuration. The arene rings
are arranged parallel to each other and perpendicular to the NSN plane, which according
to Zibarev [12] is due to stabilization by σ,π orbital interaction. This peculiarity observed
in the structure of sulfur N,Nꢀ-diaryldiimides requires further investigation. By compari-
son of the NMR spectra also the dehydrochlorination product of 3f was identified as the
corresponding sulfur N,Nꢀ-bis(2,4,6-trimethylphenyl)diimide 8b which is also described
in the literature [13,14].
It is worth mentioning that the dehydrochlorination of 3e has been reported in an old
publication. After steam distillation, a yellow oil was isolated which was claimed to be the
corresponding aryl isothiocyanate [6]. However, the authors made no attempts to iden-
tify the initial product and for that reason the reported result cannot be considered as a
conclusive investigation.
−
In extension of the study with N-aryl-1,1,1-trichloromethanesulfenamides 3a f, the
two N-alkyl-1,1,1-trichloromethanesulfenamides 3g h were also tested in the dehy-
−
drochlorination reaction. In both cases the complete conversion of the starting material

JOURNAL OF SULFUR CHEMISTRY
7
Scheme 5. Elimination of chlorine from N-(p-tolyl)-1,1,2,2,2-pentachloroethanesulfenamide (3j).
was observed. However, in both cases, the analysis of the crude material evidenced dras-
tic reduction in the mass and the formation of mixtures of non-identified decomposition
products. These results show that the presence of an N-aryl substituent is of crucial
importance for the formation and further reactions of the in situ-generated, intermediate
thiocarbonyl S-imides 1.
−
The pentachloroethanesulfenamides 3j k have never been used as precursors of the
corresponding thiocarbonyl S-imides via the dehydrochlorination method. Treatment of
3j with ethanolic potassium hydroxide solution led to the formation of an oily material
which was isolated after a reaction time of 10 min at room temperature (TLC control).
After purification, the product exhibited 13C NMR signals at 142.9 ppm and 131.1 ppm,
attributed to two Carom, as well as two other strong signals at 129.8 and 115.5 ppm, respec-
tively, attributed to two CHarom. However, no signals were found between 100 and 110 ppm
which are characteristic for CCl3 groups. Instead, two intense signals appeared at 132.4
and 116.0 ppm which are due to ethylenic carbon atoms. The elemental analysis led to
the molecular formula C9H8Cl3NS, which corresponds to a product formed from 3j by
elimination of two chlorine atoms. Based on these data, the structure of the product was
established as N-(p-tolyl)-1,2,2-trichloroethenesulfenamide 9 (Scheme 5). An analogous
attempt to perform the dehydrochlorination of the sterically crowded 3k was unsuccess-
ful. After 10 min, the starting material was completely consumed but only a complex
mixture of non-identifiable decomposition products was formed. Moreover, the expected
dechlorination product analogous to 9 could not be detected in this case, either.
Some in situ-generated thiocarbonyl S-imides, for example from the reaction of 2,2,4,4-
tetramethyl-3-thioxocyclobutanone with aryl azides (see Scheme 1), undergo a [3 + 2]-
=
cycloaddition with the C S bond as dipolarophile, yielding the corresponding 1,4,2-
dithiazolidine derivatives [15]. Based on this observation, a trapping experiment with 3a
2
and thiobenzophenone (4a) (R1
R
Ph) was performed under typical conditions. In that
=
=
case, 6a was generated in the presence of 4a. After the addition of an equimolar amount
of 3a, the blue color of thioketone 4a disappeared completely. Chromatographic work-
up gave a yellow oil. Its 1H NMR spectrum confirmed the presence of phenyl and p-tolyl
13
=
groups. In the C NMR spectrum, the characteristic signal of the C N carbon atoms
was found at 167.8 ppm. Its presence was confirmed by a strong IR absorption located
at 1660 cm−1. These data fit well with those reported for N-p-tolylbenzophenone imine
(10a) [16] (Scheme 6). An analogous reaction course was observed with di(thiophen-2-yl)
thioketone (4b) and with di(selenophen-2-yl) thioketone (4c). In both cases the expected
imines 10b–c were obtained in 89% and 88% yield, respectively.
The results show that the course of the reaction of sulfenamides 3 with potassium
hydroxide and the type of products formed under these conditions strongly depends on the

8
G. MLOSTOŃ ET AL.
Scheme 6. Reactions of the intermediate thiocarbonyl S-imide 6a, generated from sulfenamide 3a with
aromatic thioketones 4a–c.
type of the N-substituent and the perchloroalkyl residue. The in situ formation of the corre-
sponding thiocarbonyl S-imide 1 is observed in the case of less sterically hindered N-aryl
substituents. In these cases, the elusive thiocarbonyl S-imides 1 regioselectively undergo
head-to-head dimerization leading to 1,4,2,3-dithiadiazinanes 7a–d. In a recent publica-
tion [8], some of us presented results of a computational study, which showed that the
dimerization process of the N-aryl substituted 1 is kinetically controlled when the pro-
cess occurs as the head-to-head reaction. On the other hand, the head-to-tail dimerization
would be thermodynamically controlled if it would occur in the studied system. It seems
possible that in analogy to thiocarbonyl S-methanides [17], which also belong to the class
of ‘S-centered’ 1,3-dipoles, the head-to-head dimerization of chlorinated S-imides 6 can
follow a stepwise diradical mechanism (Scheme 7).
In that case, the initial step of the reaction would be the formation of resonance
stabilized diradicals of type 11.
In the systems with steric hindrance, which apparently reduces the stabilizing effect of
the N-aryl groups, a competitive reaction path leading to the formation of sulfur N,Nꢀ-
diaryldiimides 8 instead of dithiadiazinanes 7 occurs. The following reaction mechanism
is proposed (Scheme 7) – the intermediate di-radical 11 resulting from dimerization of the
transient thiocarbonyl S-imide 6 cyclizes by N,N-coupling to form the dithiadiazinanes
7a–d.
In the case of steric hindrance, diradical 11 may react by S,S-coupling yielding the
labile intermediate 1,2-dithietane derivative 12 which subsequently undergoes [2 + 2]-
cycloreversion to give tetrachloroethene and the corresponding disulfur diimide 13. The
latter compounds are known to eliminate sulfur and convert thereby into the sulfur
diimides 8a–b as final products [18]. Alternatively, the S,N-coupling of 11 may lead to
the formation of a 1,3,2-dithiazoline S-imide 14, which after [3 + 2]-cycloreversion, would
end up with 8a–b, too.
The dechlorination observed in the case of pentachloroethanesulfenamide 3j is obvi-
ously favored over the expected dehydrochlorination (Scheme 8). Analogous elimination
of chlorine from pentachloroethyl groups in the presence of a base [19] or an acid [20]
is a known process. The base-catalyzed dechlorination is expected to proceed as an E2
elimination, which is outlined in Scheme 8.
The formation of imines 10 from the in situ-generated thiocarbonyl S-imide 6a and
aryl/hetaryl thioketones 4a–c can be rationalized by the pathway presented in Scheme 9.

JOURNAL OF SULFUR CHEMISTRY
9
Scheme 7. Proposed mechanism for the formation of 1,4,2,3-dithiadiazinanes 7a–d and sulfur diimides
8a–b via the intermediate diradicals 11.
Scheme 8. Proposed mechanism for the base-catalyzed dechlorination of pentachloroethanesulfe-
namide 3j.
=
The intermediate 6a is assumed to be trapped by the C S double bond. The corresponding
5,5-dichloro-1,4,2-dithiazolidines of type 15 are formed as unstable [3 + 2]-cycloadducts.
It seems likely that after subsequent elimination of thiophosgene they undergo conver-
sion into unstable thiaziridines 16. Next, a spontaneous elimination of sulfur leads to the
isolated imines 10a–c. Thiaziridines were postulated as precursors of the corresponding
imines in reactions of aromatic thioketones with organic azides [21].

10
G. MLOSTOŃ ET AL.
Scheme 9. Proposed mechanism of the attempted [3 + 2]-cycloaddition reaction of chlorinated thio-
carbonyl S-imide 6a with thioketones 4a–c.
3. Conclusions
The present study shows that the chlorinated thiocarbonyl S-imides 1 bearing an N-
aryl ring smoothly undergo a regioselective head-to-head dimerization yielding 1,4,2,3-
dithiadiazinanes 7 as exclusive products in good yields. However, in the case of the
4-methoxyphenyl derivative 7d, a slow decomposition reaction during the storage in the
CDCl3 solution at room temperature was observed. The presence of an N-aryl substituent
without simultaneous steric hindrance at C-2 and C-6 is necessary to generate thiocar-
bonyl S-imides, which are able to undergo the dimerization reaction. On the other hand,
steric hindrance such as in 2,6-dimethylphenyl or 2,4,6-trimethylphenyl derivatives mod-
ifies the reactivity of the intermediate species, which in a multi-step reaction is converted
into sulfur N,Nꢀ-diaryldiimides. To the best of our knowledge, this is the first case of the
synthesis of their symmetrical representatives from easily available N-aryl sulfenamides via
the intermediate thiocarbonyl S-imides. The attempted trapping of a chlorinated thiocar-
bonyl S-imide with ‘superdipolarophilic’ aryl/hetaryl thioketones [22] unexpectedly led to
N-arylketimines derived from the corresponding aryl/hetaryl ketones. They are proposed
to be formed via an initial [3 + 2]-cycloaddition followed by the extrusion of thiophos-
gene from the unstable five-membered cycloadduct. The precursor of the isolated imine is
an intermediate thiaziridine which spontaneously extrudes the sulfur atom. The observed
reaction pathway results from the fact that the initially formed thiocarbonylS-imide under-
goes the [3 + 2]-cycloaddition faster than the competitive head-to-head dimerization. This
reaction sequence is only observed if the S-imide is generated in the presence of excess
thioketone.
−
In contrast to N-aryl-1,1,1-trichloromethanesulfenamides 3a f, an attempted dehy-
drochlorination of N-(p-tolyl)-1,1,2,2,2-pentachloroethanesulfenamide (3j), aimed at the
generation of trichlorothioacetyl chloride S-imides, ended with the elimination of chlorine
and formation of N-(p-tolyl)-1,2,2-trichloroethenesulfenamide (9) as the only product.
In summary, the presented results open new opportunities for the exploration of chlori-
nated thiocarbonyl S-imides in organic synthesis. The unexpected formation of sterically

JOURNAL OF SULFUR CHEMISTRY
11
crowded symmetrical sulfur N,Nꢀ-diaryldiimides of type 8, which are of interest for further
applications, for example in coordination and materials chemistry, is of special impor-
=
tance. Due to the Z,Z-configuration of both S N bonds they are also of interest for further
conformational studies.
4. Experimental design
4.1. General
Melting points (mp.) were determined in capillaries using a MEL-TEMP II apparatus
(Aldrich) and are uncorrected. IR spectra were recorded with an FT-IR NEXUS spec-
trophotometer as KBr pellets or as film; absorptions (ν) in cm−1. 1H and 13C NMR spectra
were measured on a Bruker Avance III instrument (1H: 600 MHz, 13C: 150 MHz) in CDCl3;
and chemical shifts δ are given in ppm, coupling constants J in Hz. The multiplicity of the
13C signals was deduced from DEPT, supported by 1H-13C HMQC spectra. 1H NMR data
are presented as follows: chemical shift, multiplicity (br = broad, s = singlet, d = doublet,
t = triplet, q = quartet, and m = multiplet), coupling constant, and integration. The mass
spectra were recorded on a Finnigan MAT-95 (ESI). HRMS (ESI) were registered in the
Laboratory of the Polish Academy of Sciences (CBMiM) in Łódź. Elemental analyses were
performed in the Microanalytical Laboratory of the Chemistry Faculty in Lodz. The pri-
mary amines 5a–i and trichloromethanesulfenyl chloride were obtained from commercial
sources and used as received. Pentachloroethanesulfenyl chloride was prepared according
to a literature procedure [23].
4.1.1. X-ray structure analyses
The crystal data and a summary of experimental details are reported in Table 3. Data
collection was performed with a Bruker APEX-II CCD diffractometer with graphite-
monochromated Mo-Kα radiation (λ = 0.71073 Å) in the rotation θ scan mode. Structures
were solved by use of the Shelxs-2013 program and refined by use of the Shelxl-2013
program [24].
Full crystallographic details have been deposited with the Cambridge Crystallographic
Data Centre. These data may be obtained, on request, from the CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK. Tel.: + 44 1223 336408, fax + 44 1223 336033; e-mail
http://deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk. Deposition numbers:
CCDC 1482081 (7a), 1482082 (7c), and 1482083 (8a).
−
4.2. Synthesis of sulfonamides (3a k)
The corresponding amine 5a–h (10 mmol) was dissolved in freshly distilled, anhydrous
Et2O (3–4 mL). The solution was cooled to 0°C (ice bath) and treated with small por-
tions of trichloromethanesulfenyl chloride (0.94 g, 0.55 mL) in Et2O (1.4 mL, 5 mmol) or
pentachloroethanesulfenyl chloride (1.34 g in ca. 1 mL Et2O, 5 mmol). Formation of a pre-
cipitate was observed. The reaction was continued at room temp. (15 min; TLC control,
CHCl3). For the aliphatic sulfenamides 3g, 3h, the reaction was continued at room temp.
for ca. 12 h. The reaction mixture was washed with water and the remaining ether phase
dried. After removal of the solvent under vacuum, the residue was subjected to 1H NMR

12
G. MLOSTOŃ ET AL.
Table 3. Crystal data and structure refinement for 7a, 7c, and 8a.
7a
7c
8a
Molecular formula
Molecular weight (g mol−1
Temperature (K)
Crystal system
Space group
a (pm)
C16H14Cl4N2S2
440.21
100
orthorhombic
Pna21
2922.1(3)
1056.47(12)
594.10(7)
90.00
1834.1(4)
4
C14H8Br2Cl4N2S2
569.96
100
orthorhombic
Pna21
2937.62(12)
1074.27(4)
591.45(2)
90.00
1866.50(12)
4
C16H18N2S
270.38
100
monoclinic
C2/c
1923.05(6)
758.63(3)
1137.31(4)
122.924(1)
1392.72(9)
4
)
b (pm)
c (pm)
β (°)
V (106 pm3)
Z (molecules per cell)
Dcalcd (g cm−3
)
1.594
0.874
896
2.028
5.139
1104
1.290
0.220
576
Absorption coefficient (mm−1
F (000)
)
Crystal size (mm)
θ Range for data collection (°)
Index ranges
0.32 × 0.08 × 0.05
1.39–32.50
−44 ≤ h ≤ 44,
−15 ≤ k ≤ 15,
−8 ≤ l ≤ 8
6604
0.22 × 0.07 × 0.03
1.39–32.50
−44 ≤ h ≤ 44,
−16 ≤ k ≤ 16,
−8 ≤ l ≤ 8
6720
0.18 × 0.12 × 0.10
2.52–32.50
−28 ≤ h ≤ 28,
−11 ≤ k ≤ 11,
−17 ≤ l ≤ 17
2527
Reflections collected
Reflections with [I > 2 (I)]
Function minimized
Restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2 (I)]
6158
6380
2391 ꢀ
2
2
2
2
2
=
w = 1/[ s (Fo ) + (0.0262P) + 0.9258P] where P (Fo + 2Fc )/3
1/219
1.024
1/218
1.077
0/89
1.084
R1 = 0.0876
wR2 = 0.0862
R1 = 0.0305
wR2 = 0.0292
R1 = 0.0662
wR2 = 0.0647
R1 = 0.0339
wR2 = 0.0302
−0.06(2)
R1 = 0.0488
wR2 = 0.0482
R1 = 0.0265
wR2 = 0.0236
0.269(5)
R indices (all data)
Absolute structure parameter
−
analysis in the CDCl3 solution. The crude products 3a h were used for the next step.
The crude pentachloroethanesulfenamides 3j–k were purified by column chromatography
(CHCl3).
4.2.1. N-(4-Methylphenyl)-1,1,1-trichloromethanesulfenamide (3a) [6,25]
Colorless crystals: mp. 64–65°C – crude product (lit. [25]: mp. 74–75°C); yield: 1.19 g
(93%). 1H NMR (600 MHz, CDCl3): 2.31 (s, CH3), 6.00 (br.s, NH), 7.08–7.11(m, 4H). 13
C
NMR (150 MHz, CDCl3): 20.5 (CH3), 102.4 (CCl3), 115.6, 129.7 (for 4 CH), 131.6, 142.2
(2 Carom). IR (KBr): 3338s, 1609w, 1508s, 1274w, 1220m, 1179w, 913w, 812m, 793w, 751m.
4.2.2. N-(2-Methylphenyl)-1,1,1-trichloromethanesulfenamide (3b) [5,25]
Yellow oil that crystallized and darkens in the refrigerator; mp. 36–37°C – crude product;
yield: 1.108 g (87%). 1H NMR (600 MHz, CDCl3): 2.38 (s, CH3), 6.02 (br. s, NH), 6.95 (t,
J = 7.2 Hz, 1H), 7.17 (d, J = 7.2 Hz, 1H), 7.23 (t, J = 7.8 Hz, 1H), 7.57 (d, J = 7.8 Hz, 1H).
13C NMR (150 MHz, CDCl3): 17.3 (CH3), 102.4 (CCl3), 115.1, 121.9, 127.0, 130.7 (4 CH),
124.1, 142.6 (2 C). IR (KBr): 3398m, 1603m, 1584m, 1486s, 1467m, 1401w, 1277m, 1236s,
1112m, 1049w, 922m, 786s, 748s, 723s.
4.2.3. N-(4-Bromophenyl)-1,1,1-trichloromethanesulfenamide (3c) [9]
Yellow crystals; mp. 53–54°C (crude product; lit. [9]: mp. 57–58°C); yield: 1.46 g (90%).
1H NMR (600 MHz, CDCl3): 6.08 (br., s, NH), 7.10, 7.39 (AB, J = 9.0 Hz, 4H). 13C NMR

JOURNAL OF SULFUR CHEMISTRY
13
(150 MHz, CDCl3): 102.0 (CCl3), 114.3 (1 C), 132.1, 117.2 (for 4 CH), 143.8 (1 C). IR (KBr):
3370m, 1587m, 1486s, 1442m, 1372w, 1274m, 1226m, 1173w, 1119w, 1074m, 1005m, 932w,
815s, 745s. Anal. calcd for C7H5BrCl3NS (321.45): C 26.15, H 1.57, N 4.36, S 9.98; found:
C 26.22, H 1.65, N 4.14, S 9.88.
4.2.4. N-(4-Methoxyphenyl)-1,1,1-trichloromethanesulfenamide (3d) [6]
Dark red oil; yield: 1.2 g (87%). 1H NMR (600 MHz, CDCl3): 3.80 (s, 3H, OCH3), 5.94 (br.s,
1H, NH), 6.85, 7.15 (AB, J = 9.0 Hz, 4H). 13C NMR (150 MHz, CDCl3): 55.6 (OCH3),
102.4 (CCl3), 114.5, 117.0 (for 4 CH), 138.1, 155.2 (2 C). IR (KBr): 2933w, 2828w, 1622w,
1600w, 1508s, 1255m, 1223m, 1033m, 827m, 793w, 751w. HRMS (ESI): m/z calcd. for
C8H8NOSCl3 (270.939450); found (270.939221).
4.2.5. N-(2,6-Dimethylphenyl)-1,1,1-trichloromethanesulfenamide (3e)
Yellow oil; yield: 1.0 g (73%). 1H NMR (600 MHz, CDCl3): 2.49 (br., s, 2 CH3), 5.71 (s, NH),
6.96–6.99 (m, 1 H), 7.04–7.06 (m, 2 H). 13C NMR (150 MHz, CDCl3): 19.2 (for 2 CH3),
102.5 (CCl3), 124.5, 129.1 (for 3 CH), 130.5, 141.5 (2 C). IR (KBr): 3389m, 2955m, 1597m,
1464s, 1439m, 1372m, 1264m, 1201s, 1093m, 789s, 774s, 742s. HRMS (ESI): m/z calcd for
C9H10NSCl3 [M]+ (268.959040); found (268.959956).
4.2.6. N-(2,4,6-Trimethylphenyl)-1,1,1-trichloromethanesulfenamide (3f)
1
Yellow oil; yield: 1.264 g (88%). H NMR (600 MHz, CDCl3): 2.27 (s, CH3), 2.44 (s, for
2 CH3), 5.61 (br. s, NH), 6.86 (s, 2 H). 13C NMR (150 MHz, CDCl3): 19.0, 20.6 (for 3
CH3), 102.6 (CCl3), 129.7 (for 2 CH), 139.0, 133.9, 130.6 (for 4 C). IR (KBr): 3386m,
2923m, 2854w, 1477s, 1375w, 1214s, 1154m, 853m, 783s, 758s. HRMS (ESI): m/z calcd
for C10H12NSCl3 (282.975890); found (282.975606).
4.2.7. N-Isopropyl-1,1,1-trichloromethanesulfenamide (3g) [10]
Pale yellow oil; yield: 515 mg (50%). 1H NMR (600 MHz, CDCl3): 1.25 (d, JH,H = 6.6 Hz,
2 CH3), 3.73–3.75 (m, CH), 3.96 (br.s, NH). 13C NMR (150 MHz, CDCl3): 23.4 (2 CH3),
51.7 (CH), 103.6 (CCl3).
4.2.8. N-tert-Butyl-1,1,1-trichloromethanesulfenamide (3h) [11]
Pale yellow oil; yield: 1.0 g (90%).1H NMR (600 MHz, CDCl3): 1.32 (s, t-Bu), 4.04 (br.s,
NH). 13C NMR (150 MHz, CDCl3): 30.5 (3 CH3), 55.4 (C(CH3)3), 103.7 (CCl3).
4.2.9. N-(4-Methylphenyl)-1,1,2,2,2-pentachloroethanesulfenamide (3j)
1
Yellow crystals; mp. 54–56°C; yield: 1.36 g (80%). H NMR (600 MHz, CDCl3): 3.33 (s,
CH3), 5.67 (br.s, NH), 7.05, 7.10 (AB, J = 8.4 Hz, 4H). 13C NMR (150 MHz, CDCl3): 20.5
(CH3), 104.5 (CCl2CCl3), 115.6, 129.7 (for 4 CH), 131.4, 142.6 (2 C). IR (KBr): 3341m,
1603m, 1505s, 1458w, 1435w, 1375w, 1277m, 1223m, 1176m, 1119w, 938w, 903w, 815s,
777s, 739s. Anal. calcd for C9H8NSCl5 (339.50): C 31.84, H 2.38, N 4.13, S 9.44; found: C
31.57, H 2.62, N 3.91, S 9.64.
4.2.10. N-(2,4,6-Trimethylphenyl)-1,1,2,2,2-pentachloroethanesulfenamide (3k)
Yellow oil; yield: 1.75 g (95%). 1H NMR (600 MHz, CDCl3): 2.27 (s, CH3), 2.44 (s, 2 CH3),
5.44 (br.s, NH), 6.84 (s, 2H). 13C NMR (150 MHz, CDCl3): 19.4, 20.5 (for 3 CH3), 104.1,

14
G. MLOSTOŃ ET AL.
106.0 (CCl2CCl3), 129.8, 129.9 (2 CH), 133.4, 139.3 (for 3 Carom). IR (KBr): 3389m, 2917m,
2857w, 1477s, 1439m, 1378w, 1220m, 1150w, 1030w, 859w, 834w, 738m. Anal. calcd for
C11H12NSCl5 (367.55): C 35.95, H 3.29, N 3.81, S 8.72; found: C 36.01, H 3.14, N 3.61, S
8.89.
−
−
4.3. Elimination of HCl from the sulfonamides 3a h and 3j k
The sulfenamide (1 mmol) was dissolved in freshly distilled, anhydrous Et2O (3 mL) and
the solution was cooled to 0°C (ice bath). Then, the mixture was treated with small portions
of KOH (3 mmol) in 1 mL absolute EtOH (dropwise). After each added portion of base, a
red color of the solution was observed which disappeared after few seconds. Formation of
a precipitate was also observed. After complete addition of the base, the reaction was con-
tinued at room temperature for 10 min. The precipitate of KCl was filtered off and washed
with CH2Cl2. The solvent was evaporated under reduced pressure. The crude products
were purified by column chromatography and crystallization.
In experiments with 3g−h and 3k drastic reduction in the mass and the formation of
non-identified decomposition products was observed.
4.3.1. 2,3-Bis(4-methylphenyl)-5,5,6,6-tetrachloro-1,4,2,3-dithiadiazinane (7a) [6,7]
Colorless crystals; mp 131–132°C (142°C lit. [6]); crystallization EtOH/CH2Cl2; yield:
159 mg (72%); chromatographic purification (petroleum ether:chloroform 8:2). 1H NMR
(600 MHz, CDCl3): 2.34 (s, 2 CH3), 7.16, 7.19 (AB, J = 9 Hz, 8H). 13C NMR (150 MHz,
CDCl3): 20.5 (for 2 CH3), 93.3 (for 2 CCl2), 114.9, 129.8 (for 8 CH), 132.4, 144.2 (for 4
C). IR (KBr): 2914w, 1603w, 1502s, 1236w, 1220m, 828w, 808m, 780m, 748w, 675m, 539w.
Anal. calcd for C16H14Cl4N2S2 (440.24): C 43.65, H 3.21, N 6.36, S 14.57; found: C 43.38,
H 3.25, N 6.18, S 14.41.
4.3.2. 2,3-Bis(2-methylphenyl)-5,5,6,6-tetrachloro-1,4,2,3-dithiadiazinane (7b) [25]
Colorless crystals; decompose in solution, mp. 115–117°C; yield: 115 mg (52%), purifica-
tion by repeated treatment with small portions of MeOH. 1H NMR (600 MHz, CDCl3):
2.28 (s, 2 CH3), 7.09–7.14 (m, 4H), 7.23 (t, J = 8.4 Hz, 2H), 8.15 (d, J = 7.8 Hz, 2H). 13
C
NMR (150 MHz, CDCl3): 19.2 (for 2 CH3), 94.1 (for 2 CCl2), 121.2, 126.1, 126.2, 131.2
(for 8 CH), 130.0, 149.2 (for 4 C). IR (KBr): 2971w, 2942w, 1600w, 1575w, 1483s, 1461m,
1375m, 1236m, 1188m, 1109m, 1052m, 1030m, 979m, 780s, 758s, 726s, 675s. Anal. calcd
for C16H14Cl4N2S2 (440.24): C 43.65, H 3.21, N 6.36, S 14.57; found: C 43.88, H 3.36, N
6.09, S 14.77.
4.3.3. 2,3-Bis(4-bromophenyl)-5,5,6,6-tetrachloro-1,4,2,3-dithiadiazinane (7c)
Colorless crystals; mp 154–155°C; crystallization EtOH/CH2Cl2; yield: 179 mg (63%);
1
chromatographic purification (petroleum ether:chloroform 6:4). H NMR (600 MHz,
CDCl3): 7.15, 7.46 (AB, J = 9.0 Hz, 8H). 13C NMR (150 MHz, CDCl3): 92.9 (for 2 CCl2),
115.9 (for 2 Carom), 132.3, 116.8 (for 8 CHarom), 145.4 (for 2 Carom). IR (KBr): 2923w,
1575w, 1480s, 1397w, 1239m, 1226m, 1078m, 1002m, 818s, 761m, 675s. Anal. calcd for
C14H8Br2Cl4N2S2 (569.98): C 29.50, H 1.41, N 4.91, S 11.25; found: C 29.67, H 1.27, N
4.66, S 11.02.

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15
4.3.4. 2,3-Bis(4-methoxyphenyl)-5,5,6,6-tetrachloro-1,4,2,3-dithiadiazinane (7d) [6]
Reddish solid which decomposes in the CDCl3 solution; mp. 101–102°C (after chromatog-
raphy; lit. [6]: mp. 113°C); yield: 153 mg (65%); chromatographic purification (petroleum
1
ether/CHCl3 1:1). H NMR (600 MHz, CDCl3): 3.82 (s, 6H, OCH3), 6.89, 7.23 (AB,
J = 9.0 Hz, 8H). 13C NMR (150 MHz, CDCl3): 55.6 (for 2 OCH3), 93.0 (for 2 CCl2), 114.5,
116.3 (for 8 CHarom), 140.1, 155.6 (for 4 Carom). IR (KBr): 2832w, 1499s, 1461w, 1442w,
1252m, 1040m, 821m, 777w, 672m. Anal. calcd. for C16H14Cl4N2O2S2 (472.24): C 40.69,
H 2.99, N 5.93, S 13.58; found: C 40.42, H 3.16, N 5.73, S 13.63.
4.3.5. Sulfur N,Nꢀ-bis(2,6-dimethylphenyl)diimide (8a) [12,13]
Orange crystals, mp. 57–59°C (after chromatography; lit. [12]: mp. 63–64°C); yield: 119 mg
(88%); chromatographic purification (petroleum ether/CHCl3, 6:4), 1H NMR (600 MHz,
CDCl3): 2.14 (s, 12H, CH3), 6.84–6.88 (m, 6H). 13C NMR (150 MHz, CDCl3): 18.9 (for 4
CH3), 124.8, 127.4 (for 6 CHarom), 128.4, 142.4 (for 6 Carom). IR (KBr): 2914w, 1461m,
1378m, 1280s, 1242s, 1163w, 1109m, 1097m, 1036w, 764s, 732m, 647w. MS (ESI): m/z
(%) = 271 (60, [M + H]+), 293 (100, [M + Na]+). Anal. calcd. for C16H18N2S (270.39): C
71.07, H 6.71, N 10.36, S 11.86; found: C 70.97, H 6.69, N 10.14, S 11.79.
4.3.6. Sulfur N,Nꢀ-Bis(2,4,6-trimethylphenyl)diimde (8b) [13,14]
Red-orange oil; yield: 99 mg (66%); chromatographic purification (petroleum ether:chloroform,
6:4). 1H NMR (600 MHz, CDCl3): 2.15 (s, 4 CH3), 2.25 (s, 2 CH3), 6.75 (s, 4H). 13C NMR
(150 MHz, CDCl3): 18.9, 20.6 (for 6 CH3), 128.11 (for 4 CHarom), 128.2, 134.2, 140.1 (for
8 Carom). IR (KBr): 2917m, 2860m, 1613w, 1470s, 1375w, 1312m, 1252s, 1163w, 1068w,
1040w, 856s, 729m. MS (ESI): m/z (%) = 299 (100, [M + H]+).
4.3.7. N-(4-Methylphenyl)-1,2,2-trichloroethene-1-sulfenamide (9)
Colorless oil; yield: 184 mg (68%). 1H NMR (600 MHz, CDCl3): 3.32 (s, CH3), 5.23 (br.s,
NH), 6.88, 7.03 (AB, J = 8.4 Hz, 4H). 13C NMR (150 MHz, CDCl3): 20.5 (CH3), 115.5,
129.8 (for 4 CHarom), 116.0, 131.1, 132.4, 142.9 (2 Carom and 2 Cq). IR (film): 3360s, 3037m,
3015m, 2920m, 2863m, 1609s, 1511s, 1461m, 1375m, 1280s, 1226s, 1182m, 1119m, 976m,
875s, 812s, 748s. Anal. calcd for C9H8NSCl3 (268.59): C 40.25, H 3.00, N 5.21, S 11.94;
found: C 40.45, H 3.19, N 5.41, S 11.74.
4.4. Trapping reaction of 3a with thioketones 4a–c
The corresponding thioketone 4 (1 mmol) was dissolved in freshly distilled, anhydrous
Et2O (3 mL). Then, a solution of KOH (128 mg, 2.3 mmol) in 1 mL absolute EtOH was
added. The solution was cooled to 0°C (ice bath). The mixture was treated with small por-
tions of 3a (256 mg, 1 mmol) in 1.5 mL Et2O (dropwise). Formation of a precipitate was
observed. When the addition of 3a was complete, the reaction was continued at room tem-
perature for 30 min under TLC control (petroleum ether/CHCl3 8:2). The reaction mixture
was washed with water and the remaining ether phase was dried. After removal of the sol-
vent under vacuum, the residue was subjected to 1H NMR analysis in the CDCl3 solution.
The crude products were purified by column chromatography (CHCl3/petroleum ether
4:6).

16
G. MLOSTOŃ ET AL.
4.4.1. N-(Diphenylmethylene)-4-methylaniline (10a) [26]
1
Yellow oil (lit. [26]: mp. 45–46°C); yield: 145 mg (75%). H NMR (600 MHz, CDCl3):
2.23 (s, CH3), 6.94, 6.63 (AB, J = 7.8 Hz, 4H), 7.12 (d, J = 7.8 Hz, 2H), 7.25–7.28 (m,
3H), 7.38–7.48 (m, 3H), 7.74 (d, J = 8.4 Hz, 2H), in agreement with lit. [26]. 13C NMR
(150 MHz, CDCl3): 20.8 (CH3), 121.0, 127.9, 128.1, 128.4, 129.0, 129.2, 129.5, 130.5 (for
=
14 CHarom), 132.5, 136.5, 140.0, 148.6 (4 Carom), 167.8 (C N), in agreement with lit. [26].
IR (film): 3056m, 3028m, 2920m, 1660m (C N), 1613s, 1505s, 1454s, 1321s, 1277s, 1223m,
1147m, 964m, 821m, 698s.
=
4.4.2. N-[Di(thien-2-yl)methylene]-4-methylaniline (10b)
1
Yellow oil; yield: 252 mg (89%). H NMR (600 MHz, CDCl3): 2.30 (s, CH3), 6.71 (dd,
J = 8.4, 2H), 6.99 (dd, J = 3.6 Hz, J = 4.8 Hz, 1H), 7.04 (d, J = 7.8 Hz, 2H), 7.09 (dd,
J = 3.6 Hz, J = 4.8 Hz, 1H), 7.14 (dd, J = 1.2 Hz, J = 3.6 Hz, 1H), 7.38–7.39 (m, 2H), 7.52
(dd, J = 1.2 Hz, J = 5.4 Hz, 1H).13C NMR (150 MHz, CDCl3): 20.9 (CH3), 120.7, 126.2,
127.3, 128.5, 129.2, 130.4, 131.1, 131.4 (for 10CHarom), 133.3, 135.2, 146.5, 147.9 (4Carom),
=
154.8 (C N). IR (KBr): ν = 3072w, 2920w, 1730m, 1584s, 1499m, 1426s, 1290m, 1264m,
1201m, 1116m, 1049m, 897m, 856s, 713s. MS (ESI): m/z (%) = 284 (100, [M + H]+), 306
(100, [M + Na]+). Anal. calcd for C16H13NS2 (283.41): C 67.81, H 4.62, N 4.94, S 22.63;
found: C 67.74, H 4.80, N 4.70, S 22.75.
4.4.3. N-[Di(selen-2-yl)methylene]-4-methylaniline (10c)
1
Orange viscous oil; yield: 240 mg (88%). H NMR (600 MHz, CDCl3): 2.32 (s, 3H,
CH3), 6.72, 7.03 (AB, J = 7.8 Hz, 4H), 7.25 (t, J = 4.8 Hz, 1H), 7.36 (t, J = 4.8 Hz, 1H),
7.42 (d, J = 3.6 Hz, 1H), 8.14 (d, J = 5.4 Hz, 1H), 8.19 (d, J = 3.6 Hz, 1H). 13C NMR
(150 MHz, CDCl3): 20.9 (CH3), 120.8, 128.5, 129.3, 130.1, 133.4, 133.6, 135.0, 135.8 (for 10
CHarom), 139.8, 147.9, 153.3 (for 4 Carom), 158.1 (C = N). IR (KBr): 2914w, 2851w, 1578s,
1502m, 1426m, 1800m, 1201m, 1100m, 1027m, 865m, 818m, 767m, 698s. Anal. calcd. for
C16H13NSe2 (377.20): C 50.95, H 3.47, N 3.71; found: C 51.13, H 3.66, N 3.66.
4.4.4. Computational methods
Semi-empirical PM7-type MO calculations were performed by use of the program package
Mopac 2012 [27,28]. DFT-based geometry optimizations were performed by the B3LYP
method [29,30] with 6–31G(p,d) basis sets. Dispersion correction was included [31].
The Firefly program [32] was used for the DFT calculations. All computations were
performed on a conventional PC (Pentium Dual Core CPU E5200, 2.5 GHz; 3.25 GB
RAM).
Acknowledgements
Prof. U. Behrens, Univ. Hamburg, Germany, is acknowledged for advice and support (X-ray struc-
tures). Skillful performance of microanalyses by Ms Hanna Jatczak and Ms Agnieszka Cieślińska
(University of Łódź) is gratefully acknowledged.
Disclosure statement
No potential conflict of interest was reported by the authors.

JOURNAL OF SULFUR CHEMISTRY
17
Funding
G. M. and P. P. thank the National Science Center (Cracow, Poland) for generous financial sup-
port (Grant Maestro-3 (Dec-2012/06/A/ST5/00219). A. S. thanks the Kemisk Forenings Rejsefond
(Danish Chemical Society’s Travel Fund) for a travel grant.
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