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Mol­ecules of the title compound, C12H13NO3, are not planar 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 N...O and C...O types, and by a complicated network of weak inter­molecular 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.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107034397/dn3055sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107034397/dn3055Isup2.hkl
Contains datablock I

CCDC reference: 661820

Comment top

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 very frequently used for the synthesis of various 3-substituted 4-quinolones, drugs with a broad spectrum of biological activities, such as antibacterial, anti-allergic, antiherpetic, anticancerogenic 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 findings (Repický et al., 2005), they can also be used for apoptosis (programmed cell death, PCD). The title compound, (I), was synthetized and studied because it is a suitable precursor for obtaining 3-acetyl-4-quinolone, a model compound for potential drugs. Substituted anilinomethyleneoxobutanoates are suitable objects for the study of intramolecular hydrogen bonds between imino-H atoms and the carbonyl atoms of acetyl or alkoxycarbonyl groups (Milata et al., 1990; Couchouron et al., 1983; Michalik, 1985; Hermecz et al., 1992).

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 both intra- and intermolecular hydrogen bonds (Fig. 2 and Table 2). Calculations in the solid state confirm the types of hydrogen bonds which are found from the experiment. On the first level graph-set, as defined by Bernstein et al. (1995) and Grell et al. (1999), intramolecular strings S(6), S(5) and S(6) are formed by hydrogen bonds a, b and c, respectively, and intermolecular chains C(8) by hydrogen bonds d and e (hydrogen bonds ae are defined in Table 2). On the second-level graph-set, chains C22(10) and C22(16), both formed by bonds d and e, are recognized. These two hydrogen bonds, d and e, also form an R66(42) ring, as shown in Fig. 2.

Natural bond orbital (NBO) analysis (Foster & Weinhold, 1980) of the molecular electronic structure of (I) shows that the bond orders (Wiberg indices in Fig. 3) are very close to the expected values. The exceptions are the N1—C7 and C7—C8 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 C7C8 double bond to electron-withdrawing groups (two –CO groups). As a consequence, the electrons from the nitrogen lone pair are delocalized to a formally single N1—C7 bond, lending it a partially double-bond character. In addition, π electrons from the C7C8 double bond are pulled towards the withdrawing groups through the C8—C9 and C8—C11 bonds. The possible resonance structures 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 (Smrčok et al., 2007).

Related literature top

For related literature, see: Bernstein et al. (1995); Blőchl (1994); Bylander et al. (1990); Couchouron et al. (1983); Foster & Weinhold (1980); Frisch (1998); Glendening et al. (1993); Grell et al. (1999); Hermecz et al. (1992); Huppatz et al. (1981); Kresse & Furthmüller (1996); Kresse & Hafner (1993, 1994); Kresse & Joubert (1999); Langer et al. (2006); Michalik (1985); Milata et al. (1990, 2000); Palacios et al. (1999); Perdew & Wang (1992); Perdew & Zunger (1981); Repický et al. (2005); Smrčok et al. (2007); Teter et al. (1989); Wang et al. (1997).

Experimental top

The target compound, (I), was prepared by refluxing equivalent amounts (10 mmol) of aniline and ethyl 2-ethoxymethylene-3-oxobutanoate in toluene (20 ml) for 30 min. After cooling the reaction mixture, the crude product was filtered off and recrystallized from ethanol.

Refinement top

For the X-ray data, H atoms were constrained to ideal geometry using an appropriate riding model, while the distances to the pivot atoms were free to refine. For the methyl groups, the C—C—H and O—C—H angles were kept fixed at 109.5° while the torsion angles were allowed to refine, with the starting positions based on the threefold averaged circular Fourier synthesis. The isotropic displacement parameters for the H atoms were kept at 1.5Ueq of the parent methyl C atom and at 1.2Ueq of the parent atom for the rest.

A theoretical investigation of the hydrogen bonds of (I) was performed using the Vienna ab initio simulation package VASP (Kresse & Hafner, 1993; Kresse & Furthmüller, 1996). The exchange-correlation functional is expressed in the localized density approximation (LDA) according to Perdew & Zunger (1981), together with the generalized gradient approximation (GGA) according to Perdew & Wang (1992). Plane waves form a basis set and calculations were performed using the projector-augmented wave method (Blőchl, 1994; Kresse & Joubert, 1999) and atomic pseudo-potentials (Kresse & Hafner, 1994). An optional energy cutoff controlling the accuracy of the calculation was set to 400 eV, representing an extended basis set and consequently highly accurate calculations. The optimization of the positions of the H atoms was achieved by the method of conjugated gradient in 8κ points (Teter et al., 1989; Bylander et al., 1990).

NBO (natural bond orbital) calculations were carried out by means of the NBO program (Glendening et al., 1993) included in the GAUSSIAN98 package (Frisch et al., 1998), after full optimization of the geometric parameters of the isolated molecule on the B3LYP/6–31G** level of theory.

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT and SADABS (Sheldrick, 2003); program(s) used to solve structure: SHELXTL (Bruker, 2003); program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Brandenburg, 2007); software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 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.
[Figure 2] Fig. 2. The hydrogen-bond pattern in the crystal structure of (I). See Table 2 for definitions of symbols.
[Figure 3] Fig. 3. Wiberg bond orders calculated for an isolated molecule of (I) using NBO formalism. The arrows indicate predicted transfers of electronic density.
[Figure 4] Fig. 4. Probable resonance structures of the title compound.
(E)-Methyl 2-anilinomethylene-3-oxobutanoate top
Crystal data top
C12H13NO3F(000) = 464
Mr = 219.23Dx = 1.354 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 4927 reflections
a = 5.3812 (3) Åθ = 4.6–60.6°
b = 9.9032 (6) ŵ = 0.10 mm1
c = 20.1882 (12) ÅT = 153 K
V = 1075.85 (11) Å3Needle, colourless
Z = 40.48 × 0.13 × 0.11 mm
Data collection top
Siemens SMART CCD area-detector
diffractometer
1912 independent reflections
Radiation source: fine-focus sealed tube1627 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.037
ω scansθmax = 30.5°, θmin = 2.3°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
h = 77
Tmin = 0.811, Tmax = 0.989k = 1414
17633 measured reflectionsl = 2828
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.035Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.100H atoms treated by a mixture of independent and constrained refinement
S = 1.00 w = 1/[σ2(Fo2) + (0.0591P)2 + 0.1718P]
where P = (Fo2 + 2Fc2)/3
1912 reflections(Δ/σ)max < 0.001
156 parametersΔρmax = 0.29 e Å3
0 restraintsΔρmin = 0.15 e Å3
Crystal data top
C12H13NO3V = 1075.85 (11) Å3
Mr = 219.23Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 5.3812 (3) ŵ = 0.10 mm1
b = 9.9032 (6) ÅT = 153 K
c = 20.1882 (12) Å0.48 × 0.13 × 0.11 mm
Data collection top
Siemens SMART CCD area-detector
diffractometer
1912 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
1627 reflections with I > 2σ(I)
Tmin = 0.811, Tmax = 0.989Rint = 0.037
17633 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0350 restraints
wR(F2) = 0.100H atoms treated by a mixture of independent and constrained refinement
S = 1.00Δρmax = 0.29 e Å3
1912 reflectionsΔρmin = 0.15 e Å3
156 parameters
Special details top

Experimental. Data were collected at 173 K using a Siemens SMART CCD diffractometer equipped with LT-2 A cooling device. A full sphere of reciprocal space was scanned by 0.3° steps in ω with a crystal–to–detector distance of 3.97 cm, 30 s per frame. Preliminary orientation matrix was obtained from the first 100 frames using SMART (Bruker, 2003). The collected frames were integrated using the preliminary orientation matrix which was updated every 100 frames. Final cell parameters were obtained by refinement on the position of 4927 reflections with I>10σ(I) after integration of all the frames data using SAINT (Bruker, 2003).

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.3891 (2)0.54411 (12)0.74710 (6)0.0330 (3)
O20.1743 (3)0.72893 (15)0.71974 (6)0.0445 (4)
O30.6373 (3)0.76568 (13)0.55311 (6)0.0385 (3)
N10.8676 (3)0.55310 (13)0.59931 (7)0.0252 (3)
H10.8614 (3)0.6165 (14)0.5667 (7)0.030*
C11.0545 (3)0.45329 (15)0.59415 (7)0.0228 (3)
C21.2169 (3)0.46189 (16)0.54050 (7)0.0253 (3)
H21.1981 (5)0.5312 (15)0.5090 (7)0.030*
C31.4062 (3)0.36788 (17)0.53372 (8)0.0282 (3)
H31.516 (2)0.3731 (2)0.4968 (8)0.034*
C41.4375 (3)0.26652 (17)0.58021 (8)0.0310 (3)
H41.568 (3)0.2032 (15)0.57562 (14)0.037*
C51.2757 (3)0.25836 (17)0.63356 (8)0.0299 (3)
H51.2978 (6)0.1879 (15)0.6664 (7)0.036*
C61.0822 (3)0.35021 (16)0.64043 (7)0.0267 (3)
H60.972 (2)0.3429 (2)0.6757 (8)0.032*
C70.7004 (3)0.56288 (15)0.64738 (7)0.0242 (3)
H70.7069 (3)0.4983 (14)0.6810 (7)0.029*
C80.5167 (3)0.66084 (15)0.65198 (7)0.0252 (3)
C90.4898 (3)0.76324 (15)0.60058 (8)0.0289 (3)
C100.2862 (4)0.86706 (18)0.60232 (10)0.0375 (4)
H10A0.3075 (17)0.9291 (12)0.5662 (6)0.056*
H10B0.2930 (18)0.9154 (12)0.6435 (6)0.056*
H10C0.128 (2)0.8230 (6)0.5983 (8)0.056*
C110.3438 (3)0.65230 (16)0.70802 (7)0.0269 (3)
C120.2059 (4)0.5172 (2)0.79716 (9)0.0374 (4)
H12A0.2287 (19)0.5796 (13)0.8341 (6)0.056*
H12B0.2244 (18)0.4246 (13)0.8129 (6)0.056*
H12C0.040 (2)0.5291 (15)0.7785 (3)0.056*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0323 (6)0.0348 (6)0.0318 (6)0.0043 (5)0.0073 (5)0.0024 (5)
O20.0453 (8)0.0524 (8)0.0359 (6)0.0215 (7)0.0132 (6)0.0038 (6)
O30.0409 (7)0.0330 (6)0.0416 (6)0.0076 (6)0.0127 (6)0.0079 (5)
N10.0263 (6)0.0223 (6)0.0270 (6)0.0006 (5)0.0018 (5)0.0014 (5)
C10.0212 (7)0.0221 (6)0.0253 (6)0.0008 (6)0.0010 (5)0.0043 (5)
C20.0263 (7)0.0275 (7)0.0221 (6)0.0016 (6)0.0009 (6)0.0009 (6)
C30.0239 (7)0.0349 (8)0.0259 (7)0.0010 (7)0.0028 (6)0.0057 (6)
C40.0255 (7)0.0318 (8)0.0356 (8)0.0040 (7)0.0008 (6)0.0062 (7)
C50.0318 (8)0.0264 (7)0.0316 (7)0.0034 (7)0.0016 (7)0.0018 (6)
C60.0280 (7)0.0265 (7)0.0256 (7)0.0007 (7)0.0041 (6)0.0003 (6)
C70.0239 (7)0.0237 (7)0.0251 (7)0.0025 (6)0.0011 (5)0.0049 (5)
C80.0246 (7)0.0242 (6)0.0268 (7)0.0004 (6)0.0001 (6)0.0043 (6)
C90.0295 (8)0.0227 (7)0.0345 (8)0.0003 (7)0.0017 (6)0.0023 (6)
C100.0377 (9)0.0326 (8)0.0421 (9)0.0092 (8)0.0050 (8)0.0049 (7)
C110.0267 (7)0.0296 (7)0.0244 (7)0.0005 (6)0.0014 (6)0.0062 (6)
C120.0352 (9)0.0453 (10)0.0315 (8)0.0017 (8)0.0078 (7)0.0029 (7)
Geometric parameters (Å, º) top
O1—C111.353 (2)C5—C61.389 (2)
O1—C121.437 (2)C5—H50.9695
O2—C111.210 (2)C6—H60.9300
O3—C91.245 (2)C7—C81.388 (2)
N1—C71.3269 (19)C7—H70.9340
N1—C11.4142 (19)C8—C111.467 (2)
N1—H10.9107C8—C91.458 (2)
C1—C21.394 (2)C9—C101.503 (2)
C1—C61.392 (2)C10—H10A0.9601
C2—C31.387 (2)C10—H10B0.9601
C2—H20.9412C10—H10C0.9601
C3—C41.384 (2)C12—H12A0.9761
C3—H30.9516C12—H12B0.9761
C4—C51.387 (2)C12—H12C0.9761
C4—H40.9474
C11—O1—C12115.69 (13)N1—C7—H7117.2
C7—N1—C1125.96 (13)C8—C7—H7117.2
C7—N1—H1117.0C7—C8—C11117.58 (14)
C1—N1—H1117.0C7—C8—C9120.60 (14)
C2—C1—C6119.95 (14)C11—C8—C9121.73 (14)
C2—C1—N1117.41 (13)O3—C9—C8119.88 (14)
C6—C1—N1122.64 (13)O3—C9—C10118.01 (15)
C3—C2—C1119.74 (14)C8—C9—C10122.11 (15)
C3—C2—H2120.1C9—C10—H10A109.5
C1—C2—H2120.1C9—C10—H10B109.5
C2—C3—C4120.60 (15)H10A—C10—H10B109.5
C2—C3—H3119.7C9—C10—H10C109.5
C4—C3—H3119.7H10A—C10—H10C109.5
C5—C4—C3119.49 (15)H10B—C10—H10C109.5
C5—C4—H4120.3O2—C11—O1121.24 (15)
C3—C4—H4120.3O2—C11—C8126.35 (15)
C4—C5—C6120.63 (15)O1—C11—C8112.40 (13)
C4—C5—H5119.7O1—C12—H12A109.5
C6—C5—H5119.7O1—C12—H12B109.5
C1—C6—C5119.56 (14)H12A—C12—H12B109.5
C1—C6—H6120.2O1—C12—H12C109.5
C5—C6—H6120.2H12A—C12—H12C109.5
N1—C7—C8125.65 (14)H12B—C12—H12C109.5
C7—N1—C1—C2178.57 (14)N1—C7—C8—C91.6 (2)
C7—N1—C1—C60.6 (2)C7—C8—C9—O32.2 (2)
C6—C1—C2—C30.3 (2)C11—C8—C9—O3178.61 (15)
N1—C1—C2—C3178.92 (13)C7—C8—C9—C10177.22 (15)
C1—C2—C3—C40.8 (2)C11—C8—C9—C100.8 (2)
C2—C3—C4—C50.8 (2)C12—O1—C11—O27.8 (2)
C3—C4—C5—C60.4 (2)C12—O1—C11—C8171.03 (14)
C2—C1—C6—C51.5 (2)C7—C8—C11—O2179.72 (16)
N1—C1—C6—C5177.68 (14)C9—C8—C11—O23.8 (3)
C4—C5—C6—C11.6 (2)C7—C8—C11—O11.5 (2)
C1—N1—C7—C8179.71 (14)C9—C8—C11—O1175.03 (14)
N1—C7—C8—C11178.16 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O30.911.932.6149 (18)131
C2—H2···O3i0.942.393.322 (2)169
C6—H6···O2ii0.932.523.3640 (19)151
C7—H7···O10.932.222.6256 (19)106
Symmetry codes: (i) x+1/2, y+3/2, z+1; (ii) x+1, y1/2, z+3/2.

Experimental details

Crystal data
Chemical formulaC12H13NO3
Mr219.23
Crystal system, space groupOrthorhombic, P212121
Temperature (K)153
a, b, c (Å)5.3812 (3), 9.9032 (6), 20.1882 (12)
V3)1075.85 (11)
Z4
Radiation typeMo Kα
µ (mm1)0.10
Crystal size (mm)0.48 × 0.13 × 0.11
Data collection
DiffractometerSiemens SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2003)
Tmin, Tmax0.811, 0.989
No. of measured, independent and
observed [I > 2σ(I)] reflections
17633, 1912, 1627
Rint0.037
(sin θ/λ)max1)0.714
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.035, 0.100, 1.00
No. of reflections1912
No. of parameters156
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.29, 0.15

Computer programs: SMART (Bruker, 2003), SAINT (Bruker, 2003), SAINT and SADABS (Sheldrick, 2003), SHELXTL (Bruker, 2003), SHELXTL, DIAMOND (Brandenburg, 2007).

Selected geometric parameters (Å, º) top
O2—C111.210 (2)N1—C11.4142 (19)
O3—C91.245 (2)C7—C81.388 (2)
N1—C71.3269 (19)C8—C111.467 (2)
N1—C1—C2—C3178.92 (13)N1—C7—C8—C91.6 (2)
C1—N1—C7—C8179.71 (14)
Comparison of experimental hydrogen-bonding geometry (Å, °) for compound (I) and results from the solid-state density functional theory calculations (calc_s) top
NotationD—H···AD—HH···AD···AD—H···A
aN1—H1···O30.911.932.6149 (18)131
calc_s1.041.80132.6
bC7—H7···O10.932.222.6256 (19)106
calc_s1.092.19101.1
cC10—H10B···O20.962.492.8023 (19)99
calc_s1.102.456796.5
dC2—H2···O3i0.942.393.322 (2)169
calc_s1.092.24170.5
eC6—H6···O2ii0.932.523.3640 (19)151
calc_s1.092.36152.4
Symmetry codes: (i) 1/2 + x, 3/2 - y, 1 - z; (ii) 1 - x, -1/2 + y, 3/2 - z.
 

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