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mines. The crystal and molecular structure of N-methyl-N,4-
dinitroaniline (1) is known (Anulewicz et al., 1993), therefore,
we have prepared its primary counterpart N,4-dinitroaniline
Table 2
Bond lengths in N,4-dinitroaniline and in its complex with sulfolane.
Nitramine (2) Nitramine±sulfolane complex
(
2).
Bond length ( AÊ )
(2a)
(2b)
(2a)
(2b)
C1ÐC2
C2ÐC3
C3ÐC4
C4ÐC5
C5ÐC6
C6ÐC1
C1ÐN7
N7ÐN8
N8ÐO9
N8ÐO10
C4ÐN11
N11ÐO12
N11ÐO13
1.398 (2)
1.381 (2)
1.387 (2)
1.389 (2)
1.381 (2)
1.396 (2)
1.408 (2)
1.366 (1)
1.221 (1)
1.229 (1)
1.457 (2)
1.241 (1)
1.222 (1)
1.400 (2)
1.380 (2)
1.382 (2)
1.388 (2)
1.381 (2)
1.398 (2)
1.401 (2)
1.358 (1)
1.222 (1)
1.232 (1)
1.458 (8)
1.224 (1)
1.236 (1)
1.398 (5)
1.378 (5)
1.381 (5)
1.381 (5)
1.390 (5)
1.394 (5)
1.409 (4)
1.345 (4)
1.229 (4)
1.232 (4)
1.466 (4)
1.225 (4)
1.232 (4)
1.398 (5)
1.374 (5)
1.392 (5)
1.383 (5)
1.379 (5)
1.399 (5)
1.405 (4)
1.354 (4)
1.230 (4)
1.230 (4)
1.461 (4)
1.226 (4)
1.234 (4)
2. Experimental
2
.1. Synthesis
with an Oxford cryosystem cooler (dry nitrogen gas stream,
temperature stability +/� 0.1 K. Selected crystallographic data
N,4-Dinitroaniline: to a solution of 4-nitroaniline (2.76 g,
.02 mol) in sulfolane (20 ml), absolute nitric acid (1.0 ml,
.024 mol) dissolved in acetic anhydride (4.0 ml) was added.
The mixture was maintained for 1 h at room temperature and
poured on ice and water (600 g). The solution was extracted
with ethyl ether (2 Â 50 ml), and the extract was diluted with
an equal volume of n-hexane and dried over anhydrous
magnesium sulfate. The product was adsorbed on silica gel
0
0
1
are shown in Table 1. The re¯ection intensities were collected
�
1
using the !±ꢄ scan technique (scan speed 0.3±0.15 s , scan
ꢁ
width 1 ). Two control re¯ections measured after an interval
of 50 re¯ections showed that the intensity variation was
negligible. Lorentz±polarization corrections were applied. The
SHELXTL (Sheldrick, 1990) set of programs was used for
structure solution (direct methods) and re®nement (full-
matrix least-squares method), whereas the SHELXL (Shel-
drick, 1997) program was used for drawings.
(
Kieselgel 60, E. Merck) and chromatographed on a column
using the benzene±n-hexane mixture as the eluent to remove
the excess sulfolane. The main product was eluted with
benzene and the solution was concentrated and cooled. The
nitramine±sulfolane 2:1 complex was obtained as yellow
crystals (m.p. 350±351 K) suitable for X-ray diffraction studies.
3
. Results and discussion
�
1
IR (KBr): 3242, 3218, 3159, 3138 cm (nitramide proton);
520 (asymmetric stretch of nitro groups); 1315, 1293 (envel-
opes including stretching vibrations of the nitro and sulfonyl
The synthesis was carried out according to the procedure
employed previously in N-nitration of 5-nitroindazole
1
(Zaleski et al., 1998). Sulfolane was used as an inert solvent to
1
groups); 1254 (symmetric stretch of SO group). H NMR
2
prevent acetylation with the nitric acid±acetic anhydride
mixture. To our surprise, we have obtained a molecular 2:1
complex of the nitramine and the solvent. Nitramines display a
tendency to form some complexes with solvents like acetone,
dioxane or N,N-dimethylformamide (Cobbledick & Small,
3
DMSO-d ): 8.32, d, 2H and 7.70, d, J = 9.4 Hz, 2H (aromatic
(
6
protons); 3.01±3.09, m, 4H and 2.02±2.17, m, 4H (sulfolane
ring).
Repeated crystallization from methylene chloride gave N-
(
4-nitrophenyl)nitramine free of sulfolane; m.p. 384±385 K.
1
973), but in this case it should be expected that the binding
The same compound was obtained in 58% yield when nitra-
tion with mixed anhydride was carried out in nitromethane.
Crystals suitable for X-ray diffraction studies were grown from
force is of a different nature. The nitramine free of sulfolane
was obtained by crystallization from methylene chloride or by
nitration in nitromethane solution.
methylene chloride solutions by slow cooling. MS, m/z (int):
1
In both crystals, there are two N,4-dinitroaniline molecules
in an independent part of the unit cell (Fig. 1). The differences
in bond lengths, aromatic rings and functional groups are not
large. Valence angles are more sensitive to the intermolecular
interactions in the crystal lattice, but the most signi®cant
variations are observed in the values of torsion angles (see
Tables 2±4). Three bonds of the amide nitrogen N7 are
arranged in a plane, as in typical secondary nitramines, indi-
cating trigonal hybridization of this atom. The whole nitra-
mino group in (1) is almost planar; the torsion angle along the
+
83 (M , 6), 137 (100), 121 (6), 107 (7), 91 (30), 79 (15), 64 (65),
�
1
3 (73). IR (KBr): 3331, 3272, 3184, 3120 cm (nitramide
6
proton); 1511, 1494, 1457, 1392, 1329 and 1292 cm (strong
�
1
bands in the region of the nitro group stretching vibrations).
1
H NMR (acetone-d ): 13.06, s (broad), 1H (proton on
6
3
heteroatom); 8.34, d, 2H (3,5 aromatic protons); 7.80, d, J =
1
.4 Hz, 2H (2,6-aromatic protons). C NMR (DMSO-d6):
3
9
1
44.2 (C4); 141.6 (C1); 124.9 (C3); 119.9 (C2).
ꢁ
2
.2. X-ray data collection
N7ÐN8 bond being ꢃ2 only (Anulewicz et al., 1993), while in
Data for structure determination were collected on a Kuma
Ê
1
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: LC0040). Services for accessing these data are described
at the back of the journal.
KM4 diffractometer with Mo Kꢁ radiation (ꢈ = 0.71073 A,
graphite monochromator). The diffractometer was equipped
ꢀ
Acta Cryst. (2002). B58, 109±115
Zaleski et al.
Structure of N,4-dinitroaniline 111