Structure and Reactivity of 3,3-Disubstituted 1-(5-Nitro-2,1-benzisothiazol-3-yl)triazenes

Article abstract of DOI:10.1002/ejoc.200300370

The reaction between 5-nitro-2,1-benzisothiazole-3-diazonium species and N-substituted anilines produces the 1-(5-nitro-2,1-benzisothiazol-3-yl)-3,3-disubstituted triazenes 1. These triazenes are highly stable, and even in strongly acidic medium (0.5 molL ^-1 H₂SO₄) they are only slowly decomposed back to the diazonium ion and substituted anilinium ion (for the N-ethyl derivative in 0.5 mol·L^-1 H₂SO₄ at 25 °C, t_1/2 ≈ 7 h). A series of six triazenes were characterised by their ¹H and ¹³C NMR spectra and mass spectra. Two of the triazenes were also identified by X-ray crystallography. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.

Full text of DOI:10.1002/ejoc.200300370

FULL PAPER
Structure and Reactivity of 3,3-Disubstituted 1-(5-Nitro-2,1-benzisothiazol-
3
-yl)triazenes
[a]
[b]
[c]
[d]
Josef P rˇ ikryl,* Anton ´ı n Ly cˇ ka, Valerio Bertolasi, Michal Hol cˇ apek, and
Vladim ´ı r Mach a´ cˇ ek[
e]
Keywords: Azo compounds / Nitrogen heterocycles / Synthetic methods
ium ion (for the N-ethyl derivative in 0.5 mol·L−
1
H
2
SO
4
at
The reaction between 5-nitro-2,1-benzisothiazole-3-di-
azonium species and N-substituted anilines produces the 1- 25 °C, t1/2 ഠ 7 h). A series of six triazenes were characterised
1
13
(
1
5-nitro-2,1-benzisothiazol-3-yl)-3,3-disubstituted triazenes
by their H and C NMR spectra and mass spectra. Two of
the triazenes were also identified by X-ray crystallography.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2003)
. These triazenes are highly stable, and even in strongly
−
1
acidic medium (0.5 molL
composed back to the diazonium ion and substituted anilin-
2 4
H SO ) they are only slowly de-
Introduction
We have found that azo coupling reactions between 5-
nitro-2,1-benzisothiazole-3-diazonium species and second-
ary aliphatic/aromatic amines and diphenylamine in acidic
media produces triazenes that are surprisingly stable in such
media and are split only very slowly. The structures of these
substances are dealt with in this paper. The synthetic appli-
cations and mechanistic aspects of the reactions of triazenes
1,3-Diaryltriazenes, derivatives of the hypothetical triaz-
ene HNϭNϪNH , are formed through substitution of a
2
proton by a diazonium ion in anilines or N-substituted ani-
lines. Anilines and N-alkylanilines are ambident nucleo-
[
1]
philes and can react with the electrophilic diazonium ion
at nitrogen or in the aromatic nucleus. The azo coupling
reaction at nitrogen takes place in neutral to weakly alka-
[5,6]
are summarised in refs.
[
2]
line media. In acidic media, the azo coupling reaction at
nitrogen is reversible, and so the triazenes are not stable in
Results and Discussion
acids. They are protonated by acids at the amino group and
decompose back to the aniline and diazonium ion.[
2Ϫ4]
This
An attempt to prepare 5-nitro-3-(4-ethylaminophenyl)-
azo-2,1-benzisothiazole (2) through an azo coupling reac-
tion between 5-nitro-2,1-benzisothiazole-3-diazonium ion
and N-ethylaniline by a procedure analogous to that re-
cleavage may be followed by azo coupling reaction in the
nucleus of the aniline formed (Scheme 1).
[
7]
ported in ref. did not produce the expected blue azo com-
pound 2 but instead a high yield of an isomeric orange sub-
1
13
Scheme 1
stance, identified by H and C NMR spectroscopy as 1-(5-
nitro-2,1-benzisothiazol-3-yl)-3-ethyl-3-phenyltriazene (1b).
[
[
[
a]
b]
c]
Institute of Polymeric Materials, University of Pardubice,
ˇ
N a´ m. Cs. Legi ´ı 565, 53210 Pardubice, Czech Republic
E-mail: josef.prikryl@upce.cz
Research Institute for Organic Syntheses,
5
3218 Pardubice-Rybitv ´ı , Czech Republic
E-mail: antonin.lycka@vuosas.cz
Dipartimento di Chimica and Centro di Strutturistica
Diffrattometrica, Universit a` di Ferrara
Via L. Borsari 46, 4100 Ferrara, Italy
The expected blue azo dyestuff 2, the product of an azo
coupling reaction in the aromatic nucleus, was only formed
in traces and could not be obtained by a direct coupling
reaction. We found out that 5-nitro-2,1-benzisothiazole-3-
diazonium also reacts similarly with other N-alkylanilines
and diphenylamine (Table 1).
E-mail: v.bertolasi@unife.it
[
[
d]
e]
Department of Analytical Chemistry, University of Pardubice
ˇ
N a´ m. Cs. Legi ´ı 565, 53210 Pardubice, Czech Republic
E-mail: michal.holcapek@upce.cz
Department of Organic Chemistry, University of Pardubice
ˇ
N a´ m. Cs. Legi ´ı 565, 53210 Pardubice, Czech Republic
E-mail: vladimir.machacek@upce.cz
Eur. J. Org. Chem. 2003, 4413Ϫ4421
DOI: 10.1002/ejoc.200300370
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4413

J. P rˇ ikryl, A. Ly cˇ ka, V. Bertolasi, M. Hol cˇ apek, V. Mach a´ cˇ ek
FULL PAPER
Table 1. Yields, melting points and elemental analyses of the prepared 3-substituted 1-(5-nitro-2,1-benzisothiazol-3-yl)-3-phenyltriazenes
aϪf and azo dyestuff 2
1
Compound
Yield
%
M.p.
°C
Empirical formula
Mass
Elemental analysis data (calcd./found)
% C
% H
% N
% S
% Cl
1
a
76
84
31
66
52
61
84
217Ϫ218
170Ϫ171
181Ϫ182
120Ϫ121
185Ϫ187
191Ϫ192
228Ϫ230
C
313.33
C
327.36
C
375.40
C
369.44
14
H
11
N
N
N
N
N
5
5
5
5
6
O
O
O
O
O
2
2
2
2
2
S
S
S
S
S
53.32
53.37
55.04
55.09
60.79
60.99
58.52
58.59
55.73
56.18
47.69
47.95
55.04
55.04
4.15
3.94
4.00
3.94
3.49
3.53
5.18
5.11
3.85
3.85
3.20
3.18
4.00
3.96
22.21
22.35
21.39
21.43
18.66
18.83
18.96
18.96
22.94
23.16
18.54
18.68
21.39
21.14
10.17
10.23
9.79
9.92
8.54
8.42
8.68
8.64
8.75
8.33
8.49
8.40
9.79
9.87
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
9.38
9.54
Ϫ
1
2
R ϭ CH
3
, R ϭ H
1b
15
H
13
1
2
R ϭ C
2
H
5
, R ϭ H
1c
19
H
13
1
2
R ϭ Ph, R ϭ H
1
d
18
H
19
1
2
R ϭ nBu, R ϭ CH
3
1
e
C
17
H
14
1
2
R ϭ C
2
H
4
4
CN, R ϭ CH
3
366.40
12ClN
377.81
1
f
C
15
H
5
O
3
S
1
2
R ϭ C
2
H
OH, R ϭ Cl
2
15 13 5 2
C H N O S
327.36
1
2
R ϭ CH
2
CH
3
, R ϭ H
Ϫ
Azo compound 2 was prepared by means of a coupling
reaction with the tertiary amine produced by temporary
blocking of the NH group in N-ethylaniline with the labile
CH SO Na group and subsequent removal of this group
2
3
after the completed azo coupling reaction.
The prepared triazenes 1 are characterised by their sta-
bilities in acid medium, which is unusual for triazene deriva-
[
8]
tives. They are cleaved only very slowly in acid media.
Ϫ1
Thus, in 0.5 mol·L H SO in aqueous acetic acid (1:1, v/v;
2
4
this mixture was used because of the complete insolu-
bility of triazene 1b in aqueous sulfuric acid) at 25 °C, it
was possible to observe only a very slow decrease in the
absorbance of the absorption band at λmax. ϭ 477 nm. In
order to verify that the decrease in the absorbance of the
triazene is due to its reverse decomposition to the di-
azonium ion and N-ethylanilinium, the same experiment
was carried out in the presence of 4,5-dihydroxynaphtha- mol·L H SO in aqueous acetic acid 1:1 (v/v) in the presence of
lene-2,7-disulfonic acid at a concentration 80 times that of
the triazene. 4,5-Dihydroxynaphthalene-2,7-disulfonic acid
Figure 1. Spectral record of the decomposition of triazene 1b in 0.5
Ϫ1
2
4
Ϫ3
Ϫ1
4
,5-dihydroxynaphthalene-2,7-disulfonic acid (2.5 ϫ 10 mol·L )
at 25 °C; the spectral recordings No. 1Ϫ8 were obtained at time
intervals of 0, 2, 4, 8.5, 24, 27, 30 and 33 h from the moment of
can act as a scavenger for the diazonium ion even in very mixing of the solutions. Absorbance-time dependence X(t) ϭ [A(0)
strongly acidic solution, in which it does not react as a
naphtholate but as a non-dissociated naphthol. We have
found that the decrease in absorbance at the triazene λmax. (decomposition half-life t1/2 ϭ ln2·k ϭ 417 min); spectrum No. 9
Ϫ A(ϱ)]·[1 Ϫ exp(Ϫk·t)] at 477 nm; the parameters found for the
initial absorbance A(0) ϭ 0.8836 by non-linear regression are as
Ϫ3
Ϫ1
follows: A(ϱ) ϭ 0.28311, rate constant k ϭ 1.66 ϫ 10 min
Ϫ1
is of the azo coupling product obtained from 5-nitro-2,1-benziso-
thiazole-3-diazonium and 4,5-dihydroxynaphthalene-2,7-disulfonic
(477 nm) is accompanied by an increase in absorbance at
5
79 nm, the spectra intersecting at an isosbestic point (Fig- acid in the same medium
ure 1). The solution of azo coupling product prepared from
-nitro-2,1-benzisothiazole-3-diazonium and 4,5-dihydroxy-
5
Ϫ1
naphthalene-2,7-disulfonic acid in 0.5 mol·L H SO in since the coupling component is present at a very low con-
2
4
aqueous acetic acid (1:1, v/v) shows the same spectral centration and, moreover, in its non-reactive protonated
characteristics as observed after the decomposition of triaz- form.
ene towards the end of the reaction (Figure 1, spectrum 9).
The behaviour of 5-nitro-2,1-benzisothiazole-3-di-
The decomposition of 3-ethyl-1-(5-nitro-2,1-benzisothiazol- azonium in its azo coupling reaction with N-ethylaniline in
Ϫ1
3
-yl)-3-phenyltriazene (1b) in 0.5 mol·L H SO in aque- acid medium is consistent with the general mechanism of
2 4
[
1]
ous acetic acid (1:1, v/v) obeys first order kinetics (Fig- azo coupling reactions of anilines; that is, the primary re-
ure 1), the reaction half-life determined from the decrease in versible attack of nitrogen by the electrophile is followed
the triazene absorbance being t1/2 ϭ 417 min. A very slow by an irreversible coupling reaction in the aromatic nucleus
decomposition of triazene 1b was also observed in a solu- (Scheme 1). In the case of triazene 1b, the acid-catalysed
tion of the triazene in trifluoroacetic acid. In this case, how- splitting is very slow, and the N-ethylanilinium formed does
ever, only a small amount of azo compound 2 is formed, not undergo coupling in the strongly acid medium. How-
4414
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 4413Ϫ4421

3,3-Disubstituted 1-(5-Nitro-2,1-benzisothiazol-3-yl)triazenes
FULL PAPER
The λmax. and εmax. values of the prepared triazenes 1
(Table 1) in the visible region and the same parameters of
azo dyestuff 2 are given in Table 2, together with APCI
mass spectra. The electronic spectra of compounds 1b and
2
measured in methanol are presented in Figure 2. Triaz-
enes 1 exhibit absorption maxima at the wavelengths
57Ϫ468 nm with absorption coefficients 23000 to 25500
Figure 2. Electron spectra of triazene 1b and azo compound 2 L/mol·cm, which makes them efficient chromophores. Al-
4
Ϫ5
Ϫ1
in methanol at concentrations of 2.45 ϫ 10 mol·L
though their colour strength does not reach that of azo
chromophores, it is nevertheless higher than that of anthra-
quinone chromophores.
Azo compound 2, a constitutional isomer of triazene 1b,
is a brilliant blue with the absorption maximum bathoch-
romically shifted to 590 nm and a more intense colour
strength, with εmax. ഠ 70% higher than that of triazenes 1.
ever, the formation of diazonium ion was established by its
coupling reaction with 4,5-dihydroxynaphthalene-2,7-disul-
fonic acid.
The low cleavage rates of 3-alkyl-1-(5-nitro-2,1-benziso-
thiazol-3-yl)-3-phenyltriazenes 1 in acidic media can be ex-
plained by a difference in the protonation site, as compared
NMR Spectroscopy
Protons C(4)-H, C(6)-H and C(7)-H of compounds 1 res-
with common triazenes. Triazenes are usually protonated at onate at the highest frequencies, due to the presence of a
the nitrogen atom adjacent to the azo group, and then split nitro group in the vicinity, giving a typical splitting pattern:
4
off the diazonium ion (Scheme 1). In the case of 3-alkyl-1- proton C(4)-H is split into a doublet with J
ഠ 2 Hz,
H,H
3
(
5-nitro-2,1-benzisothiazol-3-yl)-3-phenyltriazenes 1, the C(7)-H into a doublet with JH,H ഠ 10 Hz, and C(6)-H is
basicity of the nitrogen atom in the NRPh group is lowered split into a doublet of doublets with JH,H ഠ 2 and 10 Hz.
by conjugation with the nitrobenzisothiazole residue, while A typical splitting pattern was also observed for the mono-
on the other hand the protonation at the heterocyclic nitro- substituted benzene ring. ProtonϪproton connectivities in
gen is facilitated by the formation of the energetically compounds 1dϪf, possessing phenyl groups substituted by
favourable benzene system. The protonation at the hetero- methyl or chlorine in position 3Ј, were determined by gs-
cyclic nitrogen atom, however, does not allow the di- COSY.
azonium ion to split off (Scheme 2).
Proton-bearing carbon atoms were assigned unambigu-
It was impossible to determine the pK values of the con- ously from gs-HSQC spectra and quaternary carbon atoms
a
jugated acids formed by protonation at the heterocyclic and by analysis of data from gs-HMBC spectra. In the latter
the tert-amine nitrogen atoms experimentally, but the in- type of NMR spectra, the signal resonating at the highest
crease in the basicity of the heterocyclic nitrogen N(1) is frequency correlates with C(4)-H and so is C(3), the signal
indicated by the formation of an intermolecular N···HϪO at δ ഠ 161 ppm gave appropriate cross-peaks with protons
hydrogen bond, which was verified by X-ray analysis of C(4)-H and C(6)-H and so belongs to C(7a), the ipso car-
compound 1f.
bon of the phenyl group C(1Ј) correlates with the protons
Scheme 2
Eur. J. Org. Chem. 2003, 4413Ϫ4421
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4415

J. P rˇ ikryl, A. Ly cˇ ka, V. Bertolasi, M. Hol cˇ apek, V. Mach a´ cˇ ek
Table 2. Electron spectra in methanol and APCI mass spectra of triazenes 1aϪf and azo dyestuff 2
FULL PAPER
Compound
Electron spectra
APCI mass spectra
Positive ion
λ
max.
10Ϫ4·εmax.
Negative ion
(nm)
(L/mol·cm)
ϩ
Ϫ
1
a
14
461
463
467
468
457
458
2.36
2.48
2.50
2.35
2.55
2.30
[M ϩ H] (m/z ϭ 314, 100%)
M· (m/z ϭ 313, 43%)
ϩ
Ϫ
C
H
11
N
5
O
2
2
2
2
2
3
S
[M ϩ H Ϫ NO] (284)
[M ϩ H Ϫ NO Ϫ N
[M Ϫ CH
[M Ϫ CH
3
] (298)
Ϫ
ϩ
Mw ϭ 313
2
]
(256)
3
Ϫ N
2
]
(270)
S] (179,100%)
M· (m/z ϭ 327, 50%)
Ϫ
[C H O N
7 3 2 2
ϩ
Ϫ
1
C
b
15
[M ϩ H] (m/z ϭ 328, 100%)
ϩ
Ϫ
H
13
N
5
O
S
[M ϩ H Ϫ NO] (298)
[M ϩ H Ϫ NO Ϫ N
[M Ϫ CH
[M Ϫ CH
3
CH
CH
2
] (298)
Ϫ
ϩ
Mw ϭ 327
2
]
(270)
3
2
Ϫ
Ϫ N
S] (179, 100%)
2
]
(270)
[C
7
H O
3
2
N
2
ϩ
Ϫ
1
C
c
19
[M ϩ H] (m/z ϭ 376, 100%)
ϩ
M· (m/z ϭ 375, 1%)
[M Ϫ N
Ϫ
H
13
N
5
O
S
[M ϩ H Ϫ N
[M ϩ H Ϫ NO
M ϩ H Ϫ N Ϫ NO] (318)
2
]
(348)
2
] (347)
Ϫ
ϩ
Mw ϭ 375
2
]
(330)
7 3 2 2
[C H O N S] (179, 100%)
ϩ
[
2
ϩ
Ϫ
1
d
[M ϩ H] (m/z ϭ 370, 100%)
M· (m/z ϭ 369, 95%)
ϩ
Ϫ
C
18
H
19
N
5
O
S
[M ϩ H Ϫ NO] (340)
[M ϩ H Ϫ NO Ϫ N
[M Ϫ CH
[M Ϫ CH
3
CH
CH
2
CH
CH
2
CH
CH
2
] (312)
Ϫ
ϩ
Mw ϭ 369
2
]
(312)
3
N
2
Ϫ
2
2
2
Ϫ N ] (284)
[C
7
H O
3
2
2
S] (179, 100%)
ϩ
Ϫ
1
C
e
17
[M ϩ H] (m/z ϭ 367, 100%)
M· (m/z ϭ 366, 37%)
ϩ
Ϫ
H
14
N
6
O
S
[M ϩ H Ϫ NO] (337)
[M ϩ H Ϫ NO Ϫ N
[M Ϫ CH
[M Ϫ CH
2
CH
CH
2
CN] (312)
Ϫ
ϩ
Mw ϭ 366
2
]
(309)
2
N
2
Ϫ
CN Ϫ N
S] (179, 100%)
2
]
(284)
(304)
[C
7
H O
3
2
2
ϩ
Ϫ
1
C
f
15
[M ϩ H] (m/z ϭ 378, 100%)
M· (m/z ϭ 377, 39%)
[M Ϫ N
ϩ
Ϫ
H
12
N
5
O
SCl
[M ϩ H Ϫ NO] (348)
[M ϩ H Ϫ NO Ϫ N
2
]· (349)
ϩ
Ϫ
Mw ϭ 377
2
]
(320)
[M Ϫ CH
M Ϫ CH
2
CH
CH
2
OH] (332)
Ϫ
[
[
2
2
Ϫ
OH Ϫ N
2
]
C H O N S] (179, 100%)
7 3 2 2
ϩ
Ϫ
2
C
590
3.96
[M ϩ H] (m/z ϭ 328)
M· (m/z ϭ 327)
15
H
13
N
5
O
2
S
Mw ϭ 327
of the R group, etc. Both the H and the 13C signals of two [C(6Ј)], ∆δ( C) ϭ 12.8 ppm, ref. } It is presumed that the
phenyl groups in compound 1c are broadened, probably by NϪN bond order in the molecule of azo compound 2 is
restricted rotation. The NMR spectroscopic data are col- lowered due to the resonance (Scheme 4), and that, on the
1
1
13
[9]
lected in Table 3.
other hand, the NϪC(Ar) bond order is increased. This
1
The subspectra of the heterocyclic systems in both the H also produces a partial hindrance to rotation around the
1
3
and the C NMR spectra of triazenes 1 and azo compound NϪC(Ar) bond, although the restriction of rotation is not
are almost identical and all the proton and carbon signals as strong as it is in the solid phase, and only makes itself
2
are sharp. The phenyl group protons in triazenes 1 give felt in a broadening of the signals of the C(3Ј) and C(5Ј)
broadened signals. This broadening can probably be ex- carbon atoms and a large broadening of the signals of the
plained by partially hindered rotation around the C(2Ј) and C(6Ј) carbon atoms. The 13C NMR spectrum of
N(2)ϪN(3) bond, the magnitude of which is increased by a azo compound 2 at 330 K, unlike that determined at room
contribution of the polar resonance structure to the reson- temp., shows a distinct narrowing of the originally broad
ance hybrid of the molecule. Simultaneously, the bond or- signals, greater narrowing being observed with the signals
der of azo group N(1)ϭN(2) is lowered (Scheme 3).
of carbon atoms C(3Ј)and C(5Ј) (δC ؍ 112.8 ppm) than
The same effect is also manifested in the 3C NMR spec- with those of C(2Ј) and C(6Ј) (δ ؍ 128.2 ppm). This means
1
C
trum of azo compound 2. While the carbon atoms of the that even room temp. is higher than the coalescence tem-
heterocyclic skeleton and carbon atoms C(1Ј) and C(4Ј) give perature Tc.
sharp signals at room temp., the signals of carbon atoms
C(3Ј), C(5Ј) and particularly C(2Ј) and C(6Ј) are so broad
that they only could be identified in the spectrum after very
Atmospheric Pressure Chemical Ionization Mass
Spectrometry
long accumulation (δC ؍ 113 ppm and 128 ppm). In the
The positive-ion APCI mass spectra (Table 2) enabled
molecule of azobenzene in the solid phase, the rotation of unambiguous molecular weight determination due to the
ϩ
the phenyl group around the NϪC bond is hindered. The presence of protonated molecules [M ϩ H] , which are the
anisotropy of the azo group makes itself felt, which causes base peaks of the spectra for all compounds studied. Fur-
considerable anisochronism of the chemical shifts of the thermore, the presence of the nitro group is characterized
carbon atoms in the ortho positions {for azobenzene: δ ϭ by low-abundance loss of neutral NO molecules typical of
C
130.7 ppm [C(2Ј), C(3Ј) and C(5Ј)] and δC ϭ 117.9 ppm compounds containing nitro groups. The neutral loss of NO
4416
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org Eur. J. Org. Chem. 2003, 4413Ϫ4421

3,3-Disubstituted 1-(5-Nitro-2,1-benzisothiazol-3-yl)triazenes
FULL PAPER
Table 3. H and 13C shifts of compounds 1aϪf in [D
1
]DMSO
6
Pos.
No.
1a
1b
1c
1d
1e
1f
δ
H
δ
C
δ
H
δ
C
δ
H
δ
C
δ
H
δ
C
δ
H
δ
C
δ
H
δ
C
3
Ϫ
Ϫ
178.62
124.84
119.48
143.20
122.79
122.92
161.55
143.20
119.20
129.75
126.86
129.75
119.20
Ϫ
Ϫ
Ϫ
178.68
124.82
119.39
143.16
122.77
122.90
161.54
142.05
118.99
129.91
126.82
129.91
118.99
Ϫ
Ϫ
Ϫ
177.53
125.15
119.10
143.48
122.90
122.90
161.44
Ϫ
Ϫ
8.86
Ϫ
8.17
Ϫ
Ϫ
8.86
Ϫ
8.17
7.79
Ϫ
178.56
124.71
119.51
143.17
122.72
178.56
124.71
119.51
143.17
122.72
122.85
161.49
142.28
119.29
139.51
127.56
129.66
116.33
21.24
Ϫ
Ϫ
9.01
Ϫ
8.18
Ϫ
Ϫ
9.01
Ϫ
8.18
7.81
Ϫ
Ϫ
7.55
Ϫ
7.24
7.47
7.52
2.46
4.87
3.22
Ϫ
177.49
125.19
119.71
143.53
122.90
177.49
125.19
119.71
143.53
122.90
122.75
161.50
142.08
119.63
139.47
127.60
129.62
116.41
21.22
Ϫ
Ϫ
8.86
Ϫ
8.17
Ϫ
Ϫ
8.86
Ϫ
8.17
7.80
Ϫ
Ϫ
7.79
Ϫ
7.41
7.58
7.70
Ϫ
4.66
3.91
5.20(OH)
177.64
124.99
119.10
143.34
122.67
177.64
124.99
119.10
143.34
122.67
122.75
161.35
144.46
119.10
133.87
126.02
131.00
117.94
Ϫ
3
4
5
6
7
7
1
2
3
4
5
6
a
8.97
Ϫ
8.21
7.84
Ϫ
8.91
Ϫ
8.19
7.82
Ϫ
8.36
Ϫ
8.16
7.82
Ϫ
a
Ј
Ј
Ј
Ј
Ј
Ј
[a]
Ϫ
Ϫ
Ϫ
[
[
[
[
[
a]
a]
a]
a]
a]
[a]
[a]
[a]
[a]
[a]
7.72
7.61
7.43
7.61
7.72
Ϫ
7.71
7.60
7.42
7.60
7.71
Ϫ
Ϫ
7.51
Ϫ
2
R
R
Ϫ
[a]
Ϫ
[a]
1[b]
4.01
35.61
4.65
42.56
11.12
[
[
[
a]
a]
a]
[a]
[a]
[a]
1.42
7.23
7.44
7.49
2.45
4.60
1.80
1.47
1.02
46.76
27.65
19.84
13.65
42.81
14.60
118.77
50.51
56.44
Ϫ
[
a]
Phenyl groups are not equivalent and provide a complicated pattern both in H and 13C NMR spectra. [b] Arranged according to the
1
increasing distance from nitrogen atom.
X-ray Structure Determinations
ORTEP[10] views of compounds 1c and 1f are shown in
Figures 3 and 4, respectively. In both compounds the triaz-
ene group adopts the CϪNϭNϪN trans configuration and
is almost coplanar both with the 5-nitro-2,1-benzisothiazol-
Scheme 3
3-yl moiety and with the C8ϪC13 phenyl ring (for number-
ing see Figures 3 and 4). The interplanar dihedral angles in
triazene and benzothiazole derivative are 8.6(1)° and
6.3(1)°, while those between the triazene and the C8ϪC13
phenyl ring are 12.0(1)° and 15.6(1)° in 1c and 1f, respec-
tively. This arrangement allows an extended conjugation
within both molecules, with a significant contribution of
the polar resonance structure, shown in Scheme 3, to the
fundamental molecular state. The lengthening of the N3ϭ
Scheme 4
˚
N4 double bond lengths, at 1.282(2) and 1.286(3) A, relative
˚
[11]
to the standard NϭN distance of 1.24 A (ref. ), and the
shortening of the N4ϪN5 distances, at 1.331(2) and
˚
2
3
1
.326(3) A, relative to the N(sp )ϪN(sp ) single bond of
is followed by the loss of N from the azo group. Surpris- 1.40 A (ref. ), are attributable to the resonance inherent
˚
[11]
2
ingly enough, the negative-ion APCI mass spectra of all in the triazene moiety. Table 4 shows a comparison of
Ϫ
compounds exhibit the radical anion M· instead of the bond lengths in the current compounds and those in other
Ϫ
usual deprotonated molecule [M Ϫ H] . The observed frag- structures
of
1,3-diaryltriazenes
and
1-aryl-3,3-
[
12Ϫ18]
mentation paths can easily be correlated with the structure dimethyltriazenes.
All compounds display close de-
and permits the identification of functionality on the ter- localizations within the triazene moieties, and structures 1c
tiary nitrogen atom (see Exp. Sect.). The typical feature of and 1f display C1ϪN3 bond lengths of 1.379(2) and
˚
negative-ion APCI mass spectra is the stabilization of cyclic 1.390(3) A, much shorter than the standard C(aryl)ϪN sin-
Ϫ
˚
[11]
fragment ion [O NC H NSC] , producing the base peaks gle bond (1.44 A, ref. ). These data, together with the res-
2
6
3
of all the spectra.
onance within the C1ϭC2ϪC7ϭN1 atomic chain, provide
Eur. J. Org. Chem. 2003, 4413Ϫ4421
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4417

J. P rˇ ikryl, A. Ly cˇ ka, V. Bertolasi, M. Hol cˇ apek, V. Mach a´ cˇ ek
FULL PAPER
Figure 4. ORTEP view of compound 1f showing the thermal ellip-
˚
Figure 3. ORTEP view of compound 1c showing the thermal ellip-
soids at 40% probability; selected bond lengths (A) and angles (°):
˚
soids at 40% probability; selected bond lengths (A) and angles (°): S1ϪN1 1.651(2), S1ϪC1 1.706(2), N1ϪC7 1.345(3), C1ϪN3
S1ϪN1 1.643(2), S1ϪC1 1.705(2), N1ϪC7 1.338(2), C1ϪN3 1.390(3), C1ϪC2 1.395(3), C2ϪC3 1.415(3), C2ϪC7 1.434(3),
1
.379(2), C1ϪC2 1.397(2), C2ϪC3 1.407(2), C2ϪC7 1.427(2), C3ϪC4 1.354(4), C4ϪC5 1.423(4), C5ϪC6 1.349(4), C6ϪC7
C3ϪC4 1.358(2), C4ϪC5 1.410(3), C5ϪC6 1.352(3), C6ϪC7 1.424(4), N3ϪN4 1.286(3), N4ϪN5 1.326(3), N5ϪC8 1.421(3),
1.425(3), N3ϪN4 1.282(2), N4ϪN5 1.331(2), N5ϪC8 1.426(2),
N5ϪC14 1.472(3); N1ϪS1ϪC1 96.1(1), S1ϪN1ϪC7 109.2(2),
N5ϪC14 1.448(2); N1ϪS1ϪC1 96.7(1), S1ϪN1ϪC7 108.8(1), S1ϪC1ϪC2 108.9(2). S1ϪC1ϪN3 126.5(2), N3ϪC1ϪC2 124.6(2),
S1ϪC1ϪC2 108.2(1), S1ϪC1ϪN3 128.3(1), N3ϪC1ϪC2 123.5(1), C1ϪC2ϪC7 109.8(2), N1ϪC7ϪC2 115.9(2), C1ϪN3ϪN4
C1ϪC2ϪC7 109.9(1), N1ϪC7ϪC2 116.4(2), C1ϪN3ϪN4 109.9(2),
N3ϪN4ϪN5
114.6(2),
N4ϪN5ϪC8
115.4(2),
1
11.5(1),
N3ϪN4ϪN5
113.3(1),
N4ϪN5ϪC8
117.1(1), N4ϪN5ϪC14 121.6(2), C8ϪN5ϪC14 123.0(2)
N4ϪN5ϪC14 121.7(1), C8ϪN5ϪC14 120.9(1)
Table 4. Comparison of bond lengths in compounds 1c and 1f with
those in 1,3-diaryltriazenes (compounds 3Ϫ7: X ϭ Ar, Y ϭ Ar,
Z ϭ H) and 1-aryl-3,3-dimethyltriazenes (compounds 8Ϫ10: X ϭ
Ar, Y ϭ Me, Z ϭ Me)
evidence that the benzothiazole ring takes part significantly
in the triazene π-conjugation. Furthermore, compounds 1c
and 1f each display a shortening of the N5ϪC8 bond
˚
(
1.426(2) and 1.421(3) A), with respect to the standard
3
2
˚
[11]
N(sp )ϪC(sp ) distance of 1.44 A (ref. ), attributable to a
small extension of triazene delocalization to the N5ϪC8
bond, where C8 belongs to the phenyl group almost co-
planar with triazene moiety. Accordingly, the analogue Compound
1
1
2
2
3
3
3
N ϪX N ϭN
N ϪN N ϪY
N ϪZ
˚
N5ϪC14 bond length of 1.448(2) A in 1c is significantly
1
1
3
4
c
1.379(2) 1.282(2) 1.331(2) 1.426(2) 1.448(2)
1.390(3) 1.286(3) 1.326(3) 1.421(3) 1.472(3)
1.415(4) 1.267(4) 1.329(3) 1.389(4)
1.420(8) 1.260(10) 1.339(7) 1.397(11)
1.426(2) 1.261(2) 1.326(2) 1.393(2)
1.422(7) 1.267(7) 1.332(7) 1.388(8)
1.422(4) 1.274(3) 1.338(3) 1.391(4)
1.415(2) 1.282(2) 1.307(2) 1.438(2) 1.454(2)
1.433(8) 1.282(8) 1.312(8) 1.470(9) 1.466(8)
1.418(1) 1.270(1) 1.316(1) 1.445(2) 1.446(2)
longer, because C14 belongs to the C14ϪC19 phenyl ring
rotated by 78.34(5)° with respect to the triazene plane. In
f
, see ref.[
, see ref.
12]
1
1
,3-diaryltriazenes 3Ϫ7, these NϪC(aryl) distances, in the
[12]
[13]
˚
.39Ϫ1.40 A range (Table 4), indicate greater involvement 5, see ref.[
14]
15]
16]
of the 3-phenyl ring in the triazene π-conjugation.
The molecules of 1f form dimers linked by O3ϪH···N1
hydrogen bonds around centres of symmetry, as shown in
Figure 5.
6, see ref.
[
7
8
9
1
, see ref.
, see ref.[
[17]
, see ref.
0, see ref.
[18]
Experimental Section
with hot 3% ammonia, then with hot water until neutral, and dried
at 105 °C. HPLC of the product did not reveal any side products.
The substance does not melt up to 300 °C and decomposes above
3-Amino-5-nitro-2,1-benzisothiazole: Technical grade (Synthesia,
[19]
1
a.s. Pardubice), was freed of traces of 2-amino-5-nitrobenzonitrile 300 °C, in accordance with ref.
H NMR (500.13 MHz,
H,H ϭ 2.2 Hz, 1 H, C(4)-H],
10 °C for 30 min. The solution was then diluted with water and 7.96 [dd, JH,H ϭ 9.7 Hz, and JH,H ϭ 2.2 Hz, 1 H, C(6)-H], 7.32
4
and 2-cyano-5-nitrobenzamide by heating in 85% sulfuric acid at
1
6
[D ]DMSO, 298 K): δ ϭ 9.11 [d, J
3
4
3
alkalised to pH 10 by addition of aqueous ammonia. The obtained
suspension was heated to boiling, hot filtered, washed on the filter
2
[d, JH,H ϭ 9.7 Hz, 1 H, C(7)-H], 8.79 (broad s, 2 H, NH ) ppm.
1
3
C NMR (125.77 MHz, [D
6
]DMSO): δ ϭ 178.85 [C(3)], 117.61
4418
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 4413Ϫ4421

3,3-Disubstituted 1-(5-Nitro-2,1-benzisothiazol-3-yl)triazenes
FULL PAPER
Preparation of Compound 1c: Diphenylamine (8.88 g, 0.0525 mol)
was dissolved in glacial acetic acid (25 mL, 0.43 mol); emulsifier Ϫ
sodium C12-C13 alkyltriethoxysulfate (4 g) Ϫ was added, and the
solution was poured into a stirred mixture of CH
3 2
COONa·3H O
(
127 g, 0.94 mol), water (100 mL) and ice (500 g). The obtained
emulsion of diphenylamine was treated with the diazonium salt
solution (0.05 mol) (see above).
Preparation of Compound 2: Compound 2 was prepared by an azo
coupling reaction between 5-nitro-2,1-benzisothiazole-3-diazonium
and sodium N-ethyl-N-phenylaminomethanesulfonate and sub-
sequent hydrolysis of the CH SO Na group. The sodium N-ethyl-
2 3
N-phenylaminomethanesulfonate was prepared by treatment of N-
ethylaniline with formaldehyde and sodium hydrogensulfite by a
procedure analogous to that used in the preparation of other so-
dium α-aminoalkanesulfonates:[
20,21]
a solution of disodium disulf-
ite (96 g, 0.505 mol) in water (350 mL) was stirred at room temp.
and treated with aqueous formaldehyde (36%, 75 mL, 0.97 mol).
The reaction mixture was kept at 65Ϫ70 °C for 1 h, the pH value
of 7Ϫ8 being maintained by small additions of sodium carbonate
or dilute sulfuric acid. With stirring, distilled N-ethylaniline (113 g,
Figure 5. A perspective view of a dimer formed by the molecules
0.93 mol) was gradually added, the pH value being maintained at
of compound 1f linked by O3ϪH···N1 hydrogen bonds. Hydrogen
˚
bond lengths (A) and angles (°): O3ϪH 0.90(5), H···N1 2.08(5),
6Ϫ8.
O3···N1 (1 Ϫ x, Ϫy, 1 Ϫ z) 2.927(3), O3ϪH···N1 158(4)
The reaction mixture was stirred at 65Ϫ70 °C for 3 h, then heated
to 95 °C, and treated at this temperature with NaCl (60 g) (salting
out of product). The reaction mixture was then left to cool to room
temp. and stirred overnight (15 h). The separated sodium N-ethyl-
N-phenylaminomethanesulfonate was collected by suction. The ob-
tained product paste was mixed with ethanol (300 mL) on filter,
vacuum filtered, again washed with ethanol (150 mL) and again
vacuum filtered to remove the unchanged N-ethylaniline, and the
filter cake was dried at 40 °C. Yield 148.5 g product containing
[
1
C(3a) ], 121.90 [C(4)], 138.27 [C(5)], 122.56 [C(6)], 120.68 [C(7)],
60.50 [C(7a)] ppm.
N-Substituted Anilines: These coupling components were commer-
cial products (Lachema, Fluka, or SigmaϪAldrich).
Preparation of Compound 1b
78.7% sodium N-ethyl-N-phenylaminomethanesulfonate (nitro-
sation titration), i.e. yield 52.8% th. calculated on N-ethylaniline.
Diazotization of 3-Amino-5-nitro-2,1-benzisothiazole in Nitrosyl-
sulfuric Acid: Sulfuric acid (96%, 25 mL, 0.45 mol) was cooled and
stirred, and NaNO (3.48 g, 0.05 mol) was added in small portions
2
The diazonium salt solution was prepared in the way described
above. Dry sodium N-ethyl-N-phenylaminomethanesulfonate (16 g,
at such a rate as to avoid evolution of nitrous gases. The solution
was stirred and slowly heated to 70 °C until complete dissolution
of the salts. The solution of nitrosylsulfuric acid thus obtained was
stirred and cooled to 25Ϫ30 °C, and 3-amino-5-nitro-2,1-benziso-
thiazole (9.77 g, 0.05 mol) was added, after which the reaction mix-
ture was stirred at 25Ϫ30 °C for 3 h.
0.053 mol) was dissolved in water (70 mL) and treated with stirring
with CH COONa·3H O (68 g, 0.5 mol) and ice (450 g). The di-
3
2
azonium salt solution (0.05 mol) was then added drop by drop, and
the reaction mixture was stirred at room temp. for 3 h. After ad-
dition of HCl (36%, 100 mL, 1.16 mol) the reaction mixture was
heated to 85Ϫ90 °C and stirred for ca 90 min. The hydrolysis
course was monitored chromatographically (TLC: Alufol, n-hexane/
acetone, 5:3). After completion of hydrolysis, the reaction mixture
was allowed to cool to room temp., diluted with water (500 mL),
Azo Coupling Reaction of 5-Nitro-2,1-benzisothiazole-3-diazonium
with N-Ethylaniline: N-Ethylaniline (6.36 g, 0.0525 mol) was dis-
Ϫ1
solved in aqueous HCl (concd. 1 mol·L , 60 mL, 0.06 mol). The
solution was treated with charcoal (0.25 g) and Kieselguhr (0.25 g),
and after 10 min stirring the solution was filtered. The filtrate, N-
ethylanilinium chloride solution, was treated with emulsifier Ϫ so-
3
and partially neutralised by addition of NaHCO (110 g, 1.3 mol).
The precipitated azo dyestuff 2 was collected by suction, and the
filter cake was washed with water (500 mL) and dried. The yield of
crude product 2 was (15.6 g, 95% th.). After repeated recrystallis-
3 2
dium C12-C13 alkyltriethoxysulfate (2 g) and CH COONa·3H O
1
(68 g, 0.5 mol) Ϫ with stirring. The obtained emulsion of N-ethyl-
ation (3 ϫ) from ethanol m.p. 228Ϫ230 °C. H NMR (500.13 MHz,
4
aniline was mixed with finely crushed ice (450 g), and the di-
azonium salt solution (0.05 mol) was then added with stirring. The
reaction mixture was stirred for 3 h, after which the separated
orange-brown precipitate of triazene 1b was collected by suction.
[D
6
]DMSO, 298 K): δ ϭ 9.01 [ d, JH,H ϭ 2.4 Hz, 1 H, C(4)-H ],
3
4
8.20 [dd, JH,H ϭ 9.8 Hz, and JH,H ϭ 2.4 Hz, 1 H, C(6)-H], 7.83
[d, JH,H ϭ 9.8 Hz, 1 H, C(7)-H], 8.79 (triplet, JH,H ϭ 5.5 Hz, 1
H, NH), 7.92 [part of AAЈBBЈ system of 1,4-disubstituted benzene,
3
3
The filter cake was washed with distilled water (500 mL) and dried 2 H, C(2Ј)-H, C(6Ј)-H], 6.82 [part of AAЈBBЈ system of 1,4-disub-
at 80 °C. Yield of raw product (12.4 g, 76% th.). The crude product
was purified by repeated (3 ϫ) recrystallisation from acetone; m.p.
stituted benzene, 2 H, C(3Ј)-H, C(5Ј)-H], 3.34 [doublet of quad-
ruplet JH,H ϭ 5.5 Hz and 7.2 Hz, 2 H, NCH ], 1.28 (triplet,
) ppm. C NMR (125.77 MHz,
]DMSO, 298 K): δ ϭ 181.06 [C(3)], 126.36 [C(3a)), 119.39
2
3
13
170Ϫ171 °C.
JH,H ϭ 7.2 Hz, 3 H, CH
3
[D
6
The other triazenes 1, except for triazene 1c, were prepared in the
same way. The yields, melting points and elemental analyses are
given in Table 1.
[C(4)], 143.65 [C(5)], 122.87 [C(6)], 122.92 [C(7)], 161.98 [C(7a)),
143.37 [C(1Ј)], 128 [very broad signal, C(2Ј), C(6Ј)], 113 [broad sig-
nal, C(3Ј), C(5Ј)], 155.39 [C(4Ј)], 37.46 (NCH
2
), 14.11 (CH
3
) ppm.
Eur. J. Org. Chem. 2003, 4413Ϫ4421
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4419

J. P rˇ ikryl, A. Ly cˇ ka, V. Bertolasi, M. Hol cˇ apek, V. Mach a´ cˇ ek
X-ray structure determinations: X-ray diffraction data for 1c and
FULL PAPER
The electronic spectra were measured with a HewlettϪPackard
8
453 diode array spectrophotometer. The molar absorption coef- 1f were collected with a NoniusϪKappa CCD diffractometer with
Ϫ5
Ϫ1
˚
α
radiation (λ ϭ 0.7107 A). Data
ficients were determined on ca 5 ϫ 10 mol·L solutions of the
substances in methanol (Table 2). The stability of triazene 1b in
acid medium was measured by use of a ca 3 ϫ 10 mol·L solu-
graphite-monochromated Mo-K
sets were integrated by use of the Denzo-SMN package.
[
22]
The
and refined
by full-matrix, least-squares with anisotropic
Ϫ5
Ϫ1
[23]
structures were solved by direct methods (SIR97)
Ϫ1
[24]
tion of the substance in 0.5 mol·L
H
2
SO
4
in aqueous acetic acid
(SHELXL-97)
(
1:1, v/v) at 25 °C. A similar experiment was carried out in the
non-H and isotropic hydrogen atoms. All other calculations were
performed by use of PARST.[ Crystal data are given in Table 5;
selected bond lengths and angles are given in Figure 3Ϫ5.
25]
presence of 4,5-dihydroxynaphthalene-2,7-disulfonic acid of 2.5 ϫ
1
Ϫ3
Ϫ1
0
mol·L concentration.
1
13
CCDC-207356 and -207357 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the
Cambridge Crystallographic Data Centre, 12, Union Road, Cam-
bridge CB2 1EZ, UK; Fax: (internat.) ϩ44Ϫ1223/336Ϫ033;
E-mail: deposit@ccdc.cam.ac.uk].
The H and C NMR spectra were recorded with a Bruker Avance
1
13
6
spectrometer at 500.13 ( H) and 125.77 MHz ( C) in [D ]DMSO.
1
13
The H and C chemical shifts (Table 3) were referenced to the
central peaks of solvent (δ ϭ 2.55 and 39.60 ppm, respectively). All
2
D experiments (gradient-selected gs-COSY, gs-HSQC, gs-HMBC)
were performed with the aid of the manufacturerЈs software
XWIN NMR 3.1). ProtonϪproton connectivities were found by
(
gs-COSY. Protonated carbon atoms were assigned by gs-HSQC
and quaternary carbon atoms by gs-HMBC spectra.
Acknowledgments
The authors (J. P. and V. M.) are indebted to the Ministry of Edu-
cation, Youth and Sports of the Czech Republic for financial sup-
port (Research project CIMSM 253 100001). One of us (M. H.)
acknowledges the support of grant project No. 253100002 spon-
sored by the Ministry of Education, Youth, and Sports of the
Czech Republic.
Atmospheric pressure chemical ionization (APCI) mass spec-
trometry (Table 2): individual samples were dissolved in 80% aque-
ous acetonitrile and injected into the same liquid and analysed on a
quadrupole mass spectrometer Platform (Micromass, Manchester,
UK) by use of both positive-ion and negative-ion atmospheric
pressure chemical ionization (APCI) mass spectrometry under the
following conditions: the ion source temperature was 100 °C, the
APCI probe temperature was 300 °C, the cone voltage was 10 V for
positive-ion APCI and 20 V for negative-ion APCI measurements.
[1]
H. Zollinger, Diazo Chemistry I, Aromatic and Heteroaromatic
Compounds, Wiley VCH, Weinheim, 1994, chapter 13.2.,
3
91Ϫ444.
[
2]
K. Clusius, H. R. Weisser, Helv. Chim. Acta 1952, 35,
1
524Ϫ1527.
Table 5. Crystal data
[3]
H. J. Shine, MTP Int. Rev. Science. Organic Chemistry, Series
One, (Ed.: H. Zollinger), Vol. 3, Butterworth, London, 1973,
p. 83.
Structure
1c
1f
[
[
4]
5]
K. H. Saunders, R. M. L. Allen, Aromatic Diazo Compounds,
3rd Ed., Arnold, London, 1985.
D. B. Kimball, M. M. Haley, Angew. Chem. Int. Ed. 2002, 41,
3338Ϫ3351.
D. B. Kimball, T. J. R. Weakley, R. Herges, M. M. Haley, J.
Am. Chem. Soc. 2002, 124, 13463Ϫ13473.
J. Kraska, J. Sokolowska-Gajda, Pol. Pat. 133 732 1985, Chem.
Abstr. 1990, 112, 22338.
J. Bene sˇ , V. Ber a´ nek, J. Zimprich, P. Vete sˇ n ´ı k, Collect. Czech,
Chem. Commun. 1977, 42, 702Ϫ710.
Empirical formula
Molecular mass
Crystal system
Space group
C
375.40
triclinic
P1
6.9659(2)
8.2357(2)
16.2357(6)
91.835(1)
92.671(1)
108.590(1)
880.98(5)
2
19
H
13
N
5
O
2
S
15 3 3
C H12ClN O S
377.81
triclinic
¯
¯
[6]
[7]
P1
˚
a/ A
7.0275(3)
9.9995(5)
11.4618(6)
88.700(2)
88.866(2)
89.026(3)
804.96(7)
2
˚
b/ A
˚
c/ A
[
[
8]
9]
α /°
β /°
γ /°
A. M. Chippendale, A. Mathias, R. K. Harris, K. J. Packer, B.
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˚
3
V /A
[
[
[
[
[
[
[
10]
11]
12]
13]
14]
15]
16]
Z
D
calcd. /g cmϪ3
1.415
1.559
F(000)
µ /cm
388
2.092
388
3.939
Ϫ1
Temperature /K
Crystal form, colour
Crystal size /mm
295
prism, red
0.07 ϫ 0.24 ϫ 0.36 0.03 ϫ 0.12 ϫ 0.35
3.0Ϫ27.5
6677
295
plate, red
θ
min.Ϫθmax.
2.9Ϫ27.5
5964
Measured reflections
Range of h,k,l
Ϫ9,9; Ϫ10,10;
Ϫ20,20
3956
Ϫ9,9; Ϫ12,12;
Ϫ14,14
3535
Unique reflections
R
int
0.026
3087
0.031
2898
Obsd. reflections
2
2
[17]
[
F Ͼ2σ(F )]
2
R(F ) (obsd. reflections) 0.0441
0.0483
0.1296
274
2
wR(F ) all reflections
No. parameters
GOF
0.1254
296
1.069
[
[
18]
19]
1.126
∆ρ
max., ∆ρmin.
0.23; Ϫ0.22
0.34, Ϫ0.42
4420
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 4413Ϫ4421

3
,3-Disubstituted 1-(5-Nitro-2,1-benzisothiazol-3-yl)triazenes
FULL PAPER
A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C.
Giacovazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori, R.
Spagna, J. Appl. Crystallogr. 1999, 32, 115Ϫ119.
[
[
[
20]
[23]
[24]
L. Neelakantan, W. H. Hartung, J. Org. Chem. 1959, 25,
1
943Ϫ1948.
21]
22]
M. Bockmuhl, K. Windisch, (Hoechst), US Pat. 1,426,348,
922.
1
G. M. Sheldrick, SHELXL-97, Program for Refinement of
Crystal Structures, University of Göttingen, Germany, 1997.
Z. Otwinowski, W. Minor, in Methods in Enzymology, Macrom-
olecular Crystallography, Part A, (Eds.: C. W. Carter, Jr., R.
M. Sweets), Vol. 276, Academic Press, San Diego, CA, 1997,
p. 307.
[25]
M. Nardelli, J. Appl. Crystallogr. 1995, 28, 659Ϫ659.
Received June 19, 2003
Eur. J. Org. Chem. 2003, 4413Ϫ4421
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4421