(E)-Methyl 2-anilinomethyl-ene-3-oxo-butanoate: X-ray and density functional theory studies

Article abstract of DOI:10.1107/S0108270107034397

Mol-ecules of the title compound, C12H13NO3, are not planar and are stabilized by electrostatic inter-actions, as the dipole moment of the mol-ecule is 3.76 D. They are also stabilized by intra-molecular hydrogen bonds of N...O and C...O types, and by a complicated network of weak inter-molecular hydrogen bonds of the C...O type. This paper also reports the theoretical investigation of the hydrogen bonding and electronic structure of the title compound using natural bond orbital (NBO) analysis. International Union of Crystallography 2007.

Full text of DOI:10.1107/S0108270107034397

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
carbonyl atoms of acetyl or alkoxycarbonyl groups (Milata et
al., 1990; Couchouron et al., 1983; Michalik, 1985; Hermecz et
al., 1992).
ISSN 0108-2701
(
3
E)-Methyl 2-anilinomethylene-
-oxobutanoate: X-ray and density
functional theory studies
The structure of (I) is illustrated in Fig. 1 and selected
geometric parameters are given in Table 1. The molecule is not
planar but is stabilized by electrostatic interactions, as the
dipole moment of the molecule is 3.76 D. It is also stabilized by
a
b
c
Vratislav Langer, * Eva Scholtzov a , Viktor Milata and
Tom a sÏ Sol cÏ an
c
a
Environmental Inorganic Chemistry, Department of Chemical and Biological
Engineering, Chalmers University of Technology, SE-412 96 G oÈ teborg, Sweden,
b
Institute of Inorganic Chemistry, Slovak Academy of Sciences, D u bravsk a cesta 9,
c
SK-845 36 Bratislava, Slovak Republic, and Department of Organic Chemistry,
Faculty of Chemical and Food Technology, Slovak University of Technology,
Radlinsk e ho 9, SK-812 37 Bratislava, Slovak Republic
Correspondence e-mail: langer@chalmers.se
Received 27 June 2007
Accepted 13 July 2007
Online 17 August 2007
Molecules of the title compound, C H NO , are not planar
1
2
13
3
and are stabilized by electrostatic interactions, as the dipole
moment of the molecule is 3.76 D. They are also stabilized by
intramolecular hydrogen bonds of NÁ Á ÁO and CÁ Á ÁO types,
and by a complicated network of weak intermolecular
hydrogen bonds of the CÁ Á ÁO type. This paper also reports
the theoretical investigation of the hydrogen bonding and
electronic structure of the title compound using natural bond
orbital (NBO) analysis.
Figure 1
The numbering scheme of (I), with atomic displacement ellipsoids drawn
at the 50% probability level. H atoms are shown as small spheres of
arbitrary radii.
Comment
Anilinomethyleneoxobutanoates belong to a large family
of arylaminomethylene derivatives of active methylene
compounds having two electron-withdrawing groups (acetyl,
ester, cyano, nitro, etc.) on this methylene group (Hermecz et
al., 1992). These compounds are frequently used for the
synthesis of various 3-substituted 4-quinolones, which form a
class of drugs with a broad spectrum of biological activities,
such as antibacterial, anti-allergic, antiherpetic, anti-
cancerogenic, etc., used in human or veterinary medicine
(
Milata et al., 2000). They display herbicidal, germicidal and
photosynthetic activity and also inhibit photobleaching
activity (Huppatz et al., 1981; Sankyo Co. Ltd, 1981; Wang et
al., 1997). They are precursors for aminochinoline derivatives
with broad biological activities (Palacios et al., 1999) and,
according to our ®ndings (Repick y et al., 2005), they can also
be used for apoptosis (programmed cell death, PCD). The title
compound, (I), was synthesized and studied because it is a
suitable precursor for obtaining 3-acetyl-4-quinolone, a model
compound for potential drugs. Substituted anilinomethylene-
oxobutanoates are suitable subjects for the study of intra-
molecular hydrogen bonds between imino H atoms and the
Figure 2
The hydrogen-bond pattern in the crystal structure of (I); see Table 2 for
de®nition of symbols.
o552 # 2007 International Union of Crystallography
DOI: 10.1107/S0108270107034397
Acta Cryst. (2007). C63, o552±o554

organic compounds
both intra- and intermolecular hydrogen bonds (Fig. 2 and
Table 2). Calculations in the solid state con®rm the types of
hydrogen bonds found from the experiment. On the ®rst level
graph-set, as de®ned by Bernstein et al. (1995) and Grell et al.
(1999), intramolecular S(6), S(5) and S(6) strings are formed
by hydrogen bonds a, b and c, respectively, and intermolecular
Experimental
The target compound, (I), was prepared by re¯uxing equivalent
amounts (10 mmol) of aniline and methyl 2-methoxymethylene-3-
oxobutanoate in toluene (20 ml) for 30 min. After cooling the reac-
tion mixture, the crude product was ®ltered off and recrystallized
from ethanol.
C(8) chains by hydrogen bonds d and e (hydrogen bonds a±e
2
Crystal data
are de®ned in Table 2). On the second-level graph-set, C (10)
2
Ê
3
C
12
H13NO
3
V = 1075.85 (11) A
Z = 4
2
2
and C (16) chains, both formed by bonds d and e, are recog-
6
r
M = 219.23
Orthorhombic, P2 2 2
1
nized. These two hydrogen bonds, d and e, also form an R (42)
6
Mo Kꢁ radiation
ꢂ = 0.10 mm
T = 153 (2) K
1
1
Ê
� 1
a = 5.3812 (3) A
ring, as shown in Fig. 2.
Natural bond orbital (NBO) analysis (Foster & Weinhold,
Ê
b = 9.9032 (6) A
Ê
c = 20.1882 (12) A
0.48 Â 0.13 Â 0.11 mm
1
980) of the molecular electronic structure of (I) shows that
Data collection
the bond orders (Wiberg indices in Fig. 3) are very close to the
expected values. The exceptions are the N1ÐC7 and C7ÐC8
bonds, the bond orders of which are between a single and a
double bond, indicating delocalization of electrons. A detailed
analysis of the NBO results reveals that a lone pair on atom
N1 is connected through the C7 C8 double bond to electron-
withdrawing groups (two ±C O groups). As a consequence,
the electrons from the nitrogen lone pair are delocalized to a
formally single N1ÐC7 bond, lending it a partial double-bond
character. In addition, ꢀ electrons from the C7 C8 double
bond are pulled towards the withdrawing groups through the
C8ÐC9 and C8ÐC11 bonds. The possible resonance struc-
tures of compound (I) are shown in Fig. 4. Our NBO analysis
shows that the most probable structure is that illustrated in the
centre of Fig. 4. A similar electronic redistribution was found
in 2-anilinomethylene-3-oxobutanenitrile (Langer et al., 2006)
and in 5-anilinomethylene-2,2-dimethyl-1,3-dioxane-4,6-dione
Siemens SMART CCD area-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
17633 measured re¯ections
1912 independent re¯ections
1627 re¯ections with I > 2ꢃ(I)
Rint = 0.037
T
min = 0.811, Tmax = 0.989
Re®nement
2
2
R[F > 2ꢃ(F )] = 0.035
wR(F ) = 0.100
S = 1.00
H atoms treated by a mixture of
independent and constrained
re®nement
2
Ê
� 3
Áꢄmax = 0.28 e A
1
1
912 re¯ections
56 parameters
Áꢄmin = � 0.15 e AÊ
� 3
Table 1
Selected geometric parameters (A, ).
Ê
ꢀ
C7ÐN1
C7ÐC8
C8ÐC11
1.3269 (19)
1.388 (2)
1.467 (2)
C1ÐN1
O3ÐC9
O2ÐC11
1.4142 (19)
1.245 (2)
1.210 (2)
C1ÐN1ÐC7ÐC8
N1ÐC1ÐC2ÐC3
� 179.71 (14)
N1ÐC7ÐC8ÐC9
1.6 (2)
(
Smr cÏ ok et al., 2007).
178.92 (13)
Table 2
Ê
ꢀ
Comparison of experimental hydrogen-bonding geometry (A, ) for
compound (I) and results from the solid-state density functional theory
calculations (calc_s).
Notation
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
a
b
c
N1ÐH1Á Á ÁO3
0.91
1.04
0.93
1.09
0.96
1.10
0.94
1.09
0.93
1.09
1.93
1.80
2.22
2.19
2.49
2.46
2.39
2.24
2.52
2.36
2.6149 (18)
2.6256 (19)
2.8023 (19)
3.322 (2)
131
137
106
101
99
calc_s
C7ÐH7Á Á ÁO1
calc_s
C10ÐH10BÁ Á ÁO2
calc_s
C2ÐH2Á Á ÁO3
97
i
d
e
169
171
151
152
calc_s
C6ÐH6Á Á ÁO2
ii
3.3640 (19)
calc_s
1
2
3
2
1
2
3
2
Symmetry codes: (i) ‡ x; � y; 1 � z; (ii) 1 � x; � ‡ y; � z.
Figure 3
Wiberg bond orders calculated for an isolated molecule of (I) using NBO
formalism. The arrows indicate predicted transfers of electronic density.
For the X-ray data, H atoms were constrained to ideal geometry
using an appropriate riding model, while the distances to the parent
Ê
atoms were free to re®ne (CÐH = 0.93±0.98 A). For the methyl
ꢀ
groups, the CÐCÐH and OÐCÐH angles were kept ®xed at 109.5 ,
while the torsion angles were allowed to re®ne, with the starting
positions based on the threefold averaged circular Fourier synthesis.
The isotropic displacement parameters for the H atoms were kept
®xed at 1.5Ueq of the parent methyl C atom and at 1.2Ueq of the
parent atom for the rest.
Figure 4
Probable resonance structures of the title compound.
ꢁ
Acta Cryst. (2007). C63, o552±o554
Langer et al.
C
12
H
13NO
3
o553

organic compounds
A theoretical investigation of the hydrogen bonds of (I) was
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(
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ꢁ
o554 Langer et al.
C
12
H
13NO
3
Acta Cryst. (2007). C63, o552±o554