Synthesis, structural and spectral features of CH-Acids: Amides of 2,4-dinitrophenylcyanoacetic acid and their ammonium salts

Article abstract of DOI:10.1134/S1070363213050137

New N-methylmorpholinium and triethylammonium salts of 2,4- dinitrophenylcyanoacetic acid were obtained. Their electronic and spatial structure was studied by IR, NMR spectroscopy (including two-dimensional correlation spectra HMQC and HMBC), as well as b

Full text of DOI:10.1134/S1070363213050137

ISSN 1070-3632, Russian Journal of General Chemistry, 2013, Vol. 83, No. 5, pp. 959–968. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © Yu.G. Gololobov, I.R. Golding, S.V. Barabanov, V.N. Khrustalev, I.A. Garbuzova, A.S. Peregudov, 2013, published in Zhurnal
Obshchei Khimii, 2013, Vol. 83, No. 5, pp. 823–833.
To the 100th anniversary of A.A. Petrov
Synthesis, Structural and Spectral Features of CH-Acids:
Amides of 2,4-Dinitrophenylcyanoacetic Acid
and Their Ammonium Salts
Yu. G. Gololobov, I. R. Golding, S. V. Barabanov, V. N. Khrustalev,
I. A. Garbuzova, and A. S. Peregudov
Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences,
ul. Vavilova 28, Moscow, 119334 Russia
e-mail: Yugol@ineos.ac.ru
Received February 28, 2013
Abstract―New N-methylmorpholinium and triethylammonium salts of 2,4-dinitrophenylcyanoacetic acid
were obtained. Their electronic and spatial structure was studied by IR, NMR spectroscopy (including two-
dimensional correlation spectra HMQC and HMBC), as well as by XRD analysis.
DOI: 10.1134/S1070363213050137
Cyanoacetamides are promising reagents for the
synthesis of functionalized linear and heterocyclic
compounds, including biologically active substances
[1]. Cyanoacetamides undergo readily C-arylation with
2,4-di-nitrochlorobenzene in a MeCN–K2CO3 medium
[2]. The introduction of nitrophenyl substituent to the
active methylene group increases their CH-acidity by
6–8 orders of magnitude [3]. In the case of cyano-
acetamides this provides formation of stable ammo-
nium salts with triethylamine and N-methylmorpholine
[2].
compounds and discussed the peculiarities of their
structure. The structural differences of CH-acids I and
the salts II and III were examined in detail using an X-
ray diffraction analysis.
Compounds I–III used in this study were
synthesized as described in [2] by reacting the cor-
responding cyanoacetic acid amides with 2,4-dinitro-
chlorobenzene in acetonitrile in the presence of
potassium carbonate. The obtained CH-acids I react
with triethylamine or N-methylmorpholine to form
salts II or III. The structure and composition of CH-
acids I and salts II, III were confirmed by elemental
In continuation of research on the structural and
spectral characteristics of organic salts of 2,4-
dinitrophenylcyanoacetic acid and the corresponding
CH-acids we obtained new specimens of these
1
analysis data, IR, H and 13C NMR spectroscopy.
Yields, melting points, and elemental analysis data of
the compounds obtained are listed in Table 1.
10CN
8
7
2,4-NO2ClC6H3
B:
6
RHNC1(O)C2
BH+
_
RHNC(O)CH(CN)
RHNC(O)CH2CN
NO2
NO2
3
5
4
O2N
O2N
II, III
R = methyl (а), allyl (b), cyclohexyl (c); В: = Et3N (II), N-methylmorpholine (III).
I
As in other similar cases [2], in the IR spectra the
absorption bands ν(CN), ν(CO), and ν(NO2) are shifted
to the low-frequency region by 100–50 cm–1 on
passing from I to II and III, and the intensity of ν(CN)
band increases strongly (Table 2). Previously, this
phenomenon was observed for the salts of amides of
959

960
GOLOLOBOV et al.
Table 1. Yields, melting points, and elemental analysis data of compounds I–III
Found, %
Calculated, %
Comp.
Yield, %
mp, °С
Formula
no.
C
H
N
C
H
N
84
70
68
67
82
72
105–106
116–118
49.26
54.96
52.31
54.29
58.07
55.21
5.21
6.29
5.44
4.92
7.24
6.38
19.26
17.74
17.94
16.95
16.11
16.09
C15H19N5O6
C18H25N5O5
C17H21N5O6
C15H16N4O5
C21H31N5O5
C20H27N5O6
49.31
55.23
52.17
54.21
58.18
55.42
5.24
6.44
5.41
4.85
7.21
6.28
19.17
17.89
17.89
16.86
16.15
16.16
IIIа
IIb
IIIb
Ic
108–109
160–162
146–148 (decomp.)
140–142 (decomp.)
IIc
IIIc
Table 2. IR spectral parameters (ν, cm–1) of compounds I–III
Comp. no.
С≡N
C=O
1599
NO2
NH
NH+
Other
2159
1294, 1276
3413
3335
3341
3289
3318
3348
2615
2683
2724
IIIа
2163
2158
2240
2152
2156
1608
1603
1664
1606
1601
1304, 1274
1304, 1281
1531, 1346
1299, 1269
1309, 1279
1642 (C=C, allyl )
1635 (C=C, allyl )
1601 (aromatic ring)
IIb
IIIb
Ic
2673
2682
IIc
IIIc
the functionally substituted cyanoacetic acid [4], as
well as for the salts of 2,4-dinitrocyanoacetates [5].
The signals of the ring protons in the H NMR spectra
The effect of an anisotropic C(CN)CONHMe sub-
stituent close to the ortho-proton H8 averages as the
rotation accelerates. Note also that in the EXSY
spectrum of IIa there is a slow in the NMR time scale
hydrogen exchange between H8 and HDO from
DMSO-d6. At higher temperatures the remaining
signals in the 1H NMR spectrum undergo only a minor
change in the chemical shifts values.
1
are shifted upfield indicating the participation of the
ring protons in the delocalization of the charge, and it
is consistent with the data of [2]. The NMR spectra of
anionic salts II and III (Table 3, 4) are almost
independent of the substituents in the amide group. In
the COSY spectrum of compound IIa in DMSO-d6 a
doublet at 2.58 ppm gives a correlation signal with a
quartet at 6.87 ppm, confirming the assignment to the
protons of NCH3 and NHC(O) groups. At 295 K there
are weak cross-peaks between the protons H5 and H7,
and there is no correlation between the proton H7
signals and broadened signal at 7.30 ppm. When the
temperature rises to 343 K, this signal is narrowed,
shifted downfield (7.49 ppm), and appears as a doublet
with J 8.5 Hz, which gives a cross-peak with a doublet
of doublets of H5 atom. This allows the attribution of a
broad signal to the protons H8. The broadening of H8
protons signal at 295 K is apparently due to the
presence of a hindered in the NMR time scale rotation
around the probable double С1–N and С2–С3 bonds.
The assignment of the signals in the 13C NMR
spectrum was carried out on the basis of the correlation
of two-dimensional HMQC and HMBC spectra of the
same pair of model compounds Ia/IIa and compound
Ic (Table 4). In the HMQC spectrum of compound IIa
three from four closely arranged signals of the 13C
nuclei at 124.8–123.4 ppm have the correlation peaks
with three CH-protons of the ring, whereas the
remaining signal of lower intensity at 124.1 ppm
belongs to the CN-group. In the HMBC spectra the
signals at 133.3 (Ia) and 133.6 ppm (Ib) have intensive
correlation peaks with a singlet of H2 that can be
attributed to the C2 atom. The signal at 143.3 ppm in
the spectrum of salt IIa has an intensive correlation
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SYNTHESIS, STRUCTURAL AND SPECTRAL FEATURES OF CH-ACIDS
Table 3. 1Н NMR spectral parameters [δ, ppm (J, Hz)] of compounds I–IIIа
961
№
Н5
H7
H8
7.33 br.s
NH
8.24 d (1H, J 2.5)
7.79 d. d (1H, J 2.5, 9.5 )
6.85 q (1H, J 4.2)
IIIа
8.25 d (1H, J 2.5)
8.25 d (1H, J 2.6)
8.80 d (1H, J 2.3)
8.26 d (1H, J 2.3)
8.25 d (1H, J 2.3)
7.80 d. d (1H, J 2.5, 9.3)
7.81 d. d (1H, J 2.6, 9.5)
8.63 m (2Н, H7+NH)
7.35 br.s
6.97 t (1H, J 5.3)
IIb
IIIb
Ic
7.35 br.s
6.96 br.s
8.03 d (1H, J 8.7)
7.30 br.s
7.78 d. d (1H, J 2.3, 9.4)
7.76 d. d (1H, J 2.3, 9.3)
6.50 d (1H, J 7.7)
6.51 d (1H, J 7.7)
IIc
7.31 br.s
IIIc
a
Other signals, δ, ppm (J, Hz): allyl: IIb, 3.69 t (2Н, СН2, J 5.3), 5.01 d (1H, cis-H, J 10.3), 5.11 d (1H, trans-H, J 17.3), 5.80 m (1Н,
СН=); IIIb, 3.76 br.s (2Н, СН2), 5.00 d (1H, cis-H, J 10.0), 5.11 d (1H, trans-H, J 17.6), 5.80 m (1Н, СН=); cyclohexyl: Ic, 1.16–1.77
m (10Н), 3.54 br.s (1Н); IIc, IIIc, 1.17 m (5Н), 1.56 m (1Н), 1.70 m (4Н), 3.12 br.s (1Н); morpholine fragment: IIIа, 3.10 br.s (4Н),
3.75 br.s (4Н); IIIb, 3.11 br.s (4Н), 3.69 br.s (4Н); IIIc, 3.12 br.s (4Н), 3.71 br.s (4Н); СН3N: IIIа, 2.73 s (3Н); IIIb, 2.74 s (3Н); IIIc,
2.73 s (3Н); CH3C(O): IIIа, 2.59 d (3Н, J 4.2); СН3СН2: IIb, 1.19 t (9Н, CH3, J 7.3), 3.09 q (6Н, CH2, J 7.3); IIc, 1.17 t (9Н, CH3,
J 7.3), 3.08 q (6Н, CH2, J 7.3); Н2: Ic, 5.75 s (1Н).
Table 4. 13C NMR spectral parameters [δC, ppm (J, Hz)] of compounds I–IIIа
Comp. no.
С1
С2
С3
С4
С5
С6
С7
С8
С10
162.6
41.5
133.3
148.22
121.4
148.12
128.9
133.9
115.9
Iа
166.9
166.9
162.0
165.9
161.3
70.8
69.6
41.2
69.3
49.3
143.2
143.0
133.0
142.8
133.6
139.0
138.9
147.9
138.8
148.2
123.4
123.2
120.9
123.7
121.1
133.3
133.1
148.0
133.2
148.0
124.4
124.3
128.7
124.2
128.8
124.8
124.7
133.6
124.4
133.5
124.1
124.0
116.7
122.9
117.0
IIа
IIIа
Ib
IIIb
Ic
a
Other signals, δC, ppm (J, Hz): Iа, 26.6 (СН3NH); IIa, 26.5 (CH3NH), 8.9 (CH3), 46.2 (CH2, Et3NH+); IIIa, 26.5 (CH3NH), 43.1 (CH3,
N-methylmorpholinium); Ib, 41.1 (CH3NH), 115.8 (CH2=), 134.3 (CH=); IIIb, 41.3 (CH2NH), 42.9 (CH3, N-methylmorpholinium), 52.9
and 65.7 (CH2, morpholine), 114.4 (СН2=), 136.8 (СН=); Ic, 24.6, 24.7, 25.5, 32.2, 32.4. 41.7 (cyclohexyl).
peak with the doublet of doublets of the H7 atom and
corresponds to the C3 atom. The signal at 133.3 ppm in
the spectrum of salt IIa gives two weak correlation
peaks with the signals of H5 and H7 protons, and
therefore it refers to the atom C6. According to the data
of Table 4, on passing from CH-acids I to their ammo-
nium salts II and III the signals of С4, С6, С7, and С8
atoms in the 13C NMR spectra undergo diamagnetic
shift and the signals of C1, С2, С3, and С10 atoms,
paramagnetic shift.
The structure of compounds Ia, IIIa, IIIb was also
confirmed by X-ray diffraction (Figs. 1–3). The main
crystallographic and geometric parameters are shown
in Tables 5 and 6.
Compound Ia is a chiral CH-acid containing
asymmetric C2 carbon atom and crystallizing in a
chiral monoclinic space group P21. However, in this
case the determination of its absolute configuration by
the X-ray diffraction analysis is not possible due to the
lack of elements with Z > Si in their structure. Some
structural features of the molecule Ia worth
mentioning are elongated ordinary C–C bonds
involving the central carbon atom (Table 6) compared
with the average values of the lengths of appropriate
bonds C3sp–C2sp (1.50 Å), C3sp–CAr (1.51 Å) and C3sp–Csp
(1.47 Å). Apparently, this is due to the strong σ-
The spectral data show significant differences in the
electronic structure of CH-acids I and their depro-
tonated forms in ammonium salts II and III due to the
delocalization of the negative charge in the anionic
part of the salt. These structural differences were
studied in detail using the X-ray diffraction analysis.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 5 2013

962
GOLOLOBOV et al.
Fig. 1. The molecular structure of compound Ia in the non-hydrogen atoms presentation with 50% probability ellipsoids of
anisotropic displacement. The dashed line shows the intramolecular hydrogen bond.
Fig. 2. The crystal structure of compound IIIIa in the non-hydrogen atoms presentation with 40% probability ellipsoids of
anisotropic displacement. The dashed line shows the intramolecular hydrogen bond.
electron-withdrawing substituents at the C2 atom. For
the same reason, the hydrogen atom H2A at the same
carbon atom possesses sufficient acidic character and
participates in the formation of intramolecular
hydrogen bond C2–H2A···O2 (Table 7, Fig. 1) with such
a weak proton-acceptor as nitro group. In this case the
ortho-nitro group involved into the above-described
intramolecular hydrogen bond deviates slightly from
the coplanar location with the plane of the benzene
ring (the angle between the planes is 16.2°), while the
para-nitro group is materially coplanar with this ring
(interplanar angle equal to 3.2°).
dependent on the substituent type, i. e., σ-electron-
donating substituents tend to reduce, and σ-electron-
withdrawing, on the contrary, to increase the values of
the endocyclic bond angles at the carbon atoms at
positions 1,3,5 in comparison with an ideal value of
120° [7, 8]. The distribution of the values of the
endocyclic bond angles in the benzene moiety of the
molecule Ia is consistent with this principle (Table 6).
Among the exocyclic angles the angle C2C3C4 can be
distinguished, whose value is increased due to the
steric effects.
The lengths of the C–C bonds in the benzene ring
are nearly equal and close to the average value of 1.39 Å,
although it is possible to note some of their
It is known that the values of the endocyclic bond
angles in the 1-substituted benzene are largely
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 5 2013

SYNTHESIS, STRUCTURAL AND SPECTRAL FEATURES OF CH-ACIDS
963
differentiation [the bonds C4–C5, C5–C6, and C6–C7 are
slightly shorter than the bonds C3–C4, C3–C8, and
C7–C8 (Table 6)] which is more pronounced in the
anions of the compounds IIIa and IIIb. The bond
lengths of C4–N2 and C6–N3 are very close to each
other despite of the varying degrees of conjugation of
two nitro groups with the aromatic ring.
Table 5. Main crystallographic data and refinement param-
eters for compounds Iа, IIIа, IIIb
Parameter
Ia
IIIa
IIIb
Emptrical formula
M
C10H8N4O5
264.20
100
C15H19N5O6 C17H21N5O6
365.35
293
391.39
120
In the crystal, the molecules of Ia form an H-linked
chains along the b axis through weak intermolecular
hydrogen bonds N1–H1N···N4 (Table 7, Fig. 4). The
formation of intermolecular hydrogen bond between an
amine proton and cyano group is somewhat surprising,
since the structure contains a free carbonyl group,
which clearly is a stronger proton-acceptor.
T, K
Crystal system
Space group
Monoclinic
P21
Monoclinic
P21/n
Triclinic
P-1
a, Å
b, Å
c, Å
6.8232(8) 9.8404(8)
7.9897(11)
15.093(2)
15.949(2)
88.225(3)
84.711(3)
79.703(3)
1884.0(4)
4
Comparing the structure of the neutral Ia with that
of its deprotonated form in the salt IIIa (Fig. 2) and the
related anion of salt IIIb (Fig. 3) leads to some
interesting observations. It should be said that
7.8680(9)
10.3606(11)
90
15.8427(13)
11.1728(9)
90
compound IIIb crystallizes in the triclinic space group
–
α, deg
β, deg
γ, deg
V, Å3
Z
P1with two crystallographically independent structural
units per unit cell, which differ only in the conforma-
tions of the allyl fragments in the amide substituents of
anions [torsion angles C1N1C9C10, N1C9C10C11 and
C18N6C26C7, N6C26C27C28 equal –111.9(4) –120.0(4),
and –81.5(4), –1.0(6)°, respectively (Fig. 3)]. There-
fore, average values of the geometric parameters of the
two crystallographically independent structural units of
compound IIIb will be discussed below.
102.062(2)
90
93.424(2)
90
543.93(11)
2
1738.7(2)
4
d
calc, g cm–3
1.613
272
1.396
768
1.380
Due to the deprotonation the central carbon atom
C2 is carbenoid and acquires a negative charge, which
is delocalized on the long chain of the conjugated
double bonds. In accordance with this, the length of
the ordinary C–C bonds with the carbon atom C2 is
considerably shortened (Table 6). Noteworthy is the
fact that the C2–C3 bond in the anions of compounds
IIIa and IIIb is intermediate between the ordinary and
double bonds. Due to the delocalization of the negative
charge there is of redistribution of values of the bond
lengths in the dinitrophenyl substituent (Table 6).
Thus, the bond lengths of C4–C5, C5–C6 and C6–C7 are
the same, whereas the bonds C3–C4 and C3–C8 are
significantly lengthened, and C7–C8 bond is con-
siderably shortened compared with the same bonds in
the neutral CH-acid Ia. Moreover, the bond lengths of
C4–N2 and C6–N3 are different: the bond C4–N2 is
lengthened, and the bond C6–N3 is shortened. As in the
case of neutral CH-acid Ia, para-nitro group in the
salts IIIa and IIIb deviates from the coplanar position
with the plane of the benzene ring to a lesser extent
F(000)
824
μ, mm–1
2θmax, deg
0.133
56
0.110
56
0.106
54
Reflections
collected
6013
17559
17957
Independent
reflections
1384
1147
4186
2447
8203
3573
Reflections with
I > 2σ(I)
Refined parameters
173
237
507
R1 [I > 2σ(I)]
wR2 (all data)
GOF
0.0411
0.1112
1.004
0.0534
0.1593
1.000
0.0632
0.2060
1.003
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 5 2013

964
GOLOLOBOV et al.
Table 6. Some geometric parameters of compounds Iа, IIIа, IIIbа
Bond
d, Å
Angle
ω, deg
Bond
d, Å
Angle
ω, deg
Compound Ia
O1–C1
N1–C1
N2–C4
N3–C6
N4–C10
C1–C2
C2–C3
1.216(2)
1.332(2)
1.474(3)
1.468(2)
1.137(3)
1.550(3)
1.523(2)
C1C2C3
C1C2C10
C3C2C10
C2C3C4
C4C3C8
C3C4C5
C4C5C6
110.6(2)
108.0(2)
110.8(2)
123.7(2)
117.2(2)
123.0(2)
117.1(2)
C2–C10
C3–C4
C3–C8
C4–C5
C5–C6
C6–C7
C7–C8
1.493(3)
1.394(3)
1.397(3)
1.389(3)
1.384(3)
1.382(3)
1.396(3)
C5C6C7
C6C7C8
C3C8C7
123.0(2)
118.0(2)
121.7(2)
Compound IIIa
O1–C1
N1–C1
N2–C4
N3–C6
N4–C10
C1–C2
C2–C3
1.255(2)
1.352(3)
1.470(2)
1.444(3)
1.154(3)
1.440(3)
1.411(3)
C1C2C3
C1C2C10
C3C2C10
C2C3C4
C4C3C8
C3C4C5
C4C5C6
123.1(2)
117.7(2)
118.7(2)
125.6(2)
114.4(2)
123.2(2)
119.0(2)
C2–C10
C3–C4
C3–C8
C4–C5
C5–C6
C6–C7
C7–C8
1.432(3)
1.410(3)
1.421(3)
1.380(3)
1.379(3)
1.383(3)
1.363(3)
C5C6C7
C6C7C8
C3C8C7
120.5(2)
119.7(2)
123.0(2)
Compound IIIb
O1–C1
N1–C1
N2–C4
N3–C6
N4–C12
C1–C2
C2–C3
1.254(4)
1.350(4)
1.460(4)
1.449(5)
1.159(4)
1.450(5)
1.429(5)
C1C2C3
C1C2C12
C6C7C8
C3C8C7
C4C3C8
C3C4C5
C4C5C6
124.8(3)
117.1(3)
119.5(4)
123.1(4)
114.4(3)
122.9(3)
118.8(3)
C2–C12
C3–C4
C3–C8
C4–C5
C5–C6
C6–C7
C7–C8
1.411(5)
1.419(5)
1.416(5)
1.390(5)
1.380(5)
1.393(5)
1.366(5)
C5C6C7
C3C2C12
C2C3C4
120.5(3)
117.4(3)
125.6(3)
a For IIIb average values for two crystallographically independent anions are given.
[interplanar angles are 10.6 (IIIa) and 7.1° (IIIb)] than
the ortho-nitro groups [interplanar angles are 39.0
(IIIa) and 35.9° (IIIb)]. Importantly, due to the
absence of hydrogen atom at the carbenoid carbon
atom C2 and the impossibility of formation of an
intramolecular hydrogen bond with the ortho-nitro
group the repulsive interaction between these moieties
in the salts IIIa and IIIb leads both to a substantial
increase in the angle of rotation of the ortho-nitro
group relative to the ring and to a significant deviation
of its nitrogen atom from the plane of phenyl
substituent [0.257 (IIIa) and 0.327 Å (IIIb)]. In this
case, the flat conformation of the ring is slightly
distorted in the direction of a boat conformation. The
carbon atoms C3 and C6 are out of the mean square
plane passing through the remaining ring atoms [at
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 5 2013

SYNTHESIS, STRUCTURAL AND SPECTRAL FEATURES OF CH-ACIDS
Table 7. Parameters of hydrogen bonds (Å, deg) in compounds Iа, IIIа, IIIbа
965
Bond
D–H
H···A
D···A
∠(D–H···A)
Compound Ia
C2–H2A···O2
1.00
2.45
2.61
2.666(2)
3.297(2)
104
131
N1–H1N···N4 [–x, ½ + y, –z]
0.94
Compound IIIa
0.96
N5–H5N···O1
N1–H1N···O5 [x – ½, –y + ½, z + ½]
1.78
2.51
2.744(2)
3.295(3)
177
143
0.92
Compound IIIb
0.91
N1–H1N···N4 [–x + 1, –y + 1, –z]
N5–H5N···O1 [–x, –y + 1, –z + 1]
N6–H6N···N9 [–x, –y, –z + 1]
2.24
1.78
2.07
1.68
3.058(4)
2.700(4)
2.924(4)
2.650(4)
150
157
156
172
0.97
0.91
N10–H10N···O7 [–x + 1, –y + 1, –z + 1]
0.98
a D is proton-donor; A is proton-acceptor.
Fig. 3. The crystal structure of compound IIIb in the non-hydrogen atoms presentation with 50% probability ellipsoids of
anisotropic displacement. Two crystallographically independent units are presented. The dashed lines show the intramolecular
hydrogen bonds.
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966
GOLOLOBOV et al.
Fig. 4. Crystal packing of the molecules of Ia along the a axis. Only hydrogen atoms involved into the hydrogen bonding are
represented. The dashed lines show the intermolecular hydrogen bonds.
0.044 and 0.020 Å (IIIa) and 0.093 and 0.042 Å
(IIIb), respectively]. Furthermore, the value of the
endocyclic angle C4C3C8 in the ring is still more
reduced, while the values of the endocyclic angles
C4C5C6, C5C6C7, and C6C7C8 are leveled and close to
120° (Table 6). Thus, the observed structural features
of compounds IIIa and IIIb suggest clearly the
existence of their anions as two main resonance forms.
Apparently, larger value of the bond length of C4–C5
compared with the bond length of C7–C8 in the anions
IIIa and IIIb is caused by the influence of electronic
and steric effects of the ortho-nitro group at the carbon
atom C4. Cyano and amido substituents are also
involved into delocalization of the negative charge
which is manifested in the lengthening bonds C≡N,
C=O, and C–N(H) (Table 6) and shifting the absorp-
tion bands of C≡N and C=O groups to the in low-
frequency region by 50–100 cm–1 in the IR spectra.
CN
CN
R
_
R
O2N
_
O2N
NH
NH
NO2 O
NO2 O
N-Methylmorpholinium cations and anions in the
structures IIIa and IIIb form the ion pairs by strong
hydrogen bonds N+–H···O=C (Table 7, Figs 2, 3). In
the crystal of IIIa the described ion pairs form infinite
chains along direction [101] due to intermolecular
hydrogen bonds between the amide proton and the
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SYNTHESIS, STRUCTURAL AND SPECTRAL FEATURES OF CH-ACIDS
967
Fig. 5. Crystal packing of the molecules of IIIa along the b axis. Only hydrogen atoms involved into the hydrogen bonding are
represented. The dashed lines show the intermolecular hydrogen bonds.
oxygen atom of para-nitro group N–H···O (p-NO2)
(Table 7, Fig. 5). In the crystal of IIIb they form
separate centrosymmetric dimers by intermolecular
hydrogen bonds between the amide proton and the
nitrogen atom of the cyano group N–H···N≡C, which
are packed into stacks along the a axis (Table 7,
Fig. 6). Probably, a choice of proton acceptors between
the amino and cyano groups to form a three-
dimensional structure of compounds IIIa and IIIb is
dictated by the steric features of anions in ionic pairs,
i. e., by the presence of methyl or allyl groups in the
amide substituent.
EXPERIMENTAL
The NMR spectra were obtained on a spectrometer
AvanceTM-400 [400.1 (1H), 100.6 (13C) MHz]. The IR
spectra were recorded on a Magna-IR-750 Nicolet
FTIR spectrometer.
Reactions were performed under dry nitrogen
atmosphere.
Synthesis of compounds Ia, Ib, and IIa is described
in [2]. Some characteristics of the new compounds are
shown in Tables 1–4.
N-Cyclohexylamide of 2,4-dinitrophenylcyano-
acetic acid (Ib). To a solution of 2.49 g (15 mmol) of
N-cyclohexylcyanoacetamide and 3.03 g of (15 mmol)
of 2,4-dinitrochlorobenzene in 45 ml of anhydrous
acetonitrile was added 9.0 g of finely-powdered potas-
sium carbonate. The mixture was stirred at 20°C for
48 h, and the solvent was removed. To the residue
50 ml of water and 50 ml of CHCl3 and diluted
hydrochloric acid (1:5) were added in order to adjust
pH to 2–3. The organic layer was separated, and the
aqueous layer was extracted with CHCl3 (2 × 50 ml).
Therefore, the deprotonation of 2,4-dinitrophenyl-
cyanoacetic acid amides with the tertiary amines
results in the formation of salts in which the anion part
undergoes great changes in geometric and electronic
structure compared with the original CH-acids. In this
13
case, the C NMR signals of the ring of the salts are
shifted upfield, and the exocyclic, downfield. In the
structure of compounds I–III intra- and intermolecular
hydrogen bonds of the amide proton and ammonium
cations with O- and N-proton-acceptors play an
important role.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 5 2013

968
GOLOLOBOV et al.
X-ray diffraction analysis of compounds Ia, IIIa,
IIIb. The unit cell parameters and the intensity of the
reflections of compounds Ia, IIIa, IIIb were measured
on an automatic three-circle diffractometers Bruker
SMART APEX II CCD (λMoKα-radiation, graphite
monochromator, φ- and ω-scanning) (Ia) and Bruker
SMART 1000 CCD (λMoKα-radiation, graphite mono-
chromator, φ- and ω-scanning) (IIIa, IIIb). The main
crystallographic data are shown in Table 5. The struc-
tures of the compounds were solved by the direct
method and refined by the full matrix least squares
method in the anisotropic approximation for non-
hydrogen atoms. The hydrogen atoms of amino groups
were objectively localized by Fourier syntheses and
refined with the fixed positional and thermal
parameters. Positions of the remaining hydrogen atoms
were geometrically calculated and included into the
refinement with fixed positional (rider model) and
thermal parameters [Uiso(H) = 1.5Ueq(C) for CH3-
groups and Uiso(H) = 1.2Ueq(C) for all other groups].
All calculations were performed using SHELXTL
software package [9]. Tables of atomic coordinates,
bond lengths, bond angles, and anisotropic thermal
parameters for compounds Ia, IIIa, IIIb are deposited
in the Cambridge Structural Database.
Fig. 6. Crystal packing of the molecules of IIIb along the a
ACKNOWLEDGMENTS
axis. Only hydrogen atoms involved into the hydrogen
bonding are represented. The dashed lines show the
intermolecular hydrogen bonds.
This work was financially supported by the Russian
Foundation for Basic Research (grant no. 08-03-
00196a).
REFERENCES
The combined extracts were dried over anhydrous
sodium sulfate and potassium carbonate, and then
filtered. The solvent was removed, and the residue was
1. D’yachenko, V.D., Tkachev, R.P., and Bityukova, O.S.,
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2. Gololobov, Yu.G., Gol’ding, I.R., Ter’ye, F., Petrov-
skii, P.V., Lysenko, K.A., and Garbuzova, I.A., Izv.
Akad. Nauk., Ser. Khim., 2009, p. 2365.
crystallized from
a
chloroform–petroleum ether
mixture (2:1). Yield 3.34 g (67%).
3. Kavalec, F., Manacek, V., and Sterba, V., Collect.
Chech. Chem. Commun., 1976, vol. 41, p. 590.
4. Gololobov, Yu.G., Linchenko, O.A., Gol’ding, I.R.,
Galkina, M.A., Krasnova, I.A, Garbuzova, and I.A.
Petrovskii, P.V., Izv. Akad. Nauk., Ser. Khim., 2005,
p. 2323.
5. Gololobov, Yu.G., Linchenko, O.A., Petrovskii, P.V.,
Starikova, Z.A., and Garbuzova, I.A., Heteroatom
Chem., 2007, vol. 18, p. 108.
6. International Tables for Crystallography, 2006, vol. C,
ch. 9.5, p. 790.
7. Domenicano, A., Vaciago, A., and Coulson, C.A., Acta
Cryst. (В), 1975, vol. 31, p. 221.
N-Methylmorpholinium N-methylcarboxamido-
2,4-dinitrocyclohexa-2,5-dienide (IIIa), triethyl-
ammonium and N-methylmorpholinium N-cyclo-
hexylcarboxamido-2,4-dinitrocyclohexa-2,5-dienides
(IIc, IIIc), triethylammonium and N-methylmor-
pholinium N-allylcarboxamido-2,4- dinitrocyclo-
hexa-2,5-dienides (IIb, IIIb) were obtained by the
general procedure. To a solution of 1 mmol of the
amide I in 8 ml of a diethyl ether–MeCN mixture (1:1)
was added a solution of 0.2 g (2 mmol) of triethyl-
amine or N-methylmorpholine in 4 ml of ether. The
mixture was stirred for 5 h at 20°C. After adding 4 ml
of petroleum ether, the mixture was kept overnight at –
10°C. The carmine red precipitate was separated,
washed with ether, and dried in vacuum.
8. Domenicano, A. and Vaciago, A., Acta Crystallogr. (В),
1979, vol. 35, p. 1382.
9. Sheldrick, G.M., Acta Crystallogr. (А), 2008, vol. 64,
p. 112.
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