N-(2-Amino­phen­yl)maleamic acid

The title compound [also called (Z)-3-(2-amino­phenyl­carbamo­yl)propenoic acid], C₁₀H₁₀N₂O₃, is a non-planar amidated maleic acid derivative, with the mean planes through the 2-amino­phenyl and maleamic acid groups inclined at an angle of 43.08 (10)°. Symmetry-related mol­ecules are linked by inter­molecular N—H...N hydrogen bonds, forming centrosymmetric amine–amide dimers. The dimers are linked by N—H...O and C—H...O hydrogen bonds and weak N—H...π and π–π inter­actions [C-to-centroid distance 3.510 (3) Å] into a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.041
• wR factor = 0.051
• Data-to-parameter ratio = 8.1

checkCIF/PLATON results

No syntax errors found



Alert level C
REFNR01_ALERT_3_C  Ratio of reflections to parameters is < 10 for a
            centrosymmetric structure
            sine(theta)/lambda                0.6741
            Proportion of unique data used    0.4777
            Ratio reflections to parameters   8.1338
PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low ....         48 Perc.
PLAT088_ALERT_3_C Poor Data / Parameter Ratio ....................       8.13
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C1
PLAT420_ALERT_2_C D-H Without Acceptor       N6     -   H62    ...          ?

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          2

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The title compound, (I), has been prepared by condensation from maleic anhydride and o-phenylenediamine as a intermediary for the synthesis of 1,2,3,4-tetrahydroquinoxalin-2-ones.

In the molecular structure of compound (I), the C2—C3 bond length of the maleamic moiety proves to have a clear double bond character and the bonds C1—C2 and C3—C4 are clearly single bonds, which confirms localized bonding, Table 1. The maleamic moiety is characterized by a rather short and almost linear O—H···O intramolecular hydrogen bond forming an S(7) ring (Bernstein et al., 1995), Figure 1. The C—O distances in the carboxylic acid group are consistent with the position of the carboxyl H atom deduced from difference maps. The title compound is non-planar with the mean planes through the 2-aminophenyl and maleamic acid groups being inclined against each other at an angle of 43.08 (10)°.

The crystal packing for (I) shows that the molecules are linked by two close to linear N—H···N hydrogen bonds (see Table 2 for geometric parameters and symmetry codes) to form centrosymmetric R²₂(10) dimers (Figure 2). These hydrogen bonds probably are the reason for the non-planarity of compound (I).

Adjacent dimers of (I) are linked by N—H···O and C—H···O hydrogen bonds and also by weaker N—H···π contacts and π···π stacking interactions. Amino atom N6 acts as a hydrogen-bond donor, via H61, to atom O2 in the molecule at (-x, y - 1/2, -z + 1/2), while atom C7 at (-x, y - 1/2, -z + 1/2), in turn, acts as donor to O2 at (x, y - 1, z). In this manner, a C(10) chain is formed (motif a, Figure 3.), running along the c axis. The arrangement of N6—H61···O2ⁱⁱ, N6ⁱⁱ—H61ⁱⁱ···O2^iv, C7ⁱⁱⁱ—H7ⁱⁱⁱ···O4^iv, C7—H7···O4ⁱⁱⁱ interactions can be described by the graph-set notation R⁴₄(28). Aromatic carbon atom C7 acts as a hydrogen-bond donor, via H7, to O4 in the molecule at (-x + 1, y - 1/2, -z + 3/2), while C7 at (-x + 1, y - 1/2, -z + 3/2), in turn, acts as a donor to O4 at (x, y - 1, z). In this manner, a C(7) zigzag chain (motif b) is formed, running along the b axis, Figure 3. The geometry of the hydrogen bonding is given in Table 2. The amine hydrogen atom H62 is forming a N—H···π interaction with aromatic carbon C9 at (-x + 1, y - 1/2, -z + 3/2). These interactions are dominated by dispersion energies, Vaupel et al. (2006). Lastly, maleamic moieties do interact with the C5—C10 benzene ring (centroid Cg) at (x - 1, -y + 3/2, z - 1/2), the distance C1···Cg is 3.510 (3) Å and the gamma angle is 22.8°, Figure 4.

Related literature

For related literature, see: Bernstein et al. (1995); Vaupel et al. (2006).

S2. Experimental

To a solution of o-phenylenediamine (9.2 mmol) in THF (20 ml) is added a solution of maleic anhydride (0.91 g, 9.3 mmol) in THF (20 ml). The suspension was stirred for 12 h at room temperature. The mixture was filtered and the solvent distilled off. The residue was precipitated with a mixture of acetone/hexane to give a yellow solid (1.87 g, 98%), which was washed with ethyl ether and recrystallized from THF to give yellow crystals suitable for single-crystal X-ray diffraction (m.p. 412–413 K). R_f (4:6:0.1, hexane: AcOEt: formic acid) 0.23. ¹H NMR (300.13 MHz, DMSO-d₆): δ 9.85 (s, 1H, CO₂H), 8.04 (bs, 2H, NH₂), 7.14 (bd, J = 7.9 Hz, 1H, H10), 6.97 (td, J = 7.9, 1.2 Hz, 1H, H8), 6.74 (bd, J = 7.9 Hz, 1H, H7), 6.61 (d, J = 12.2 Hz, 1H, H3), 6.56 (td, J = 7.9, 1.0 Hz, 1H, H9), 6.27 (d, J = 12.2 Hz, 1H, H2); ¹³C NMR (75.47 MHz, DMSO-d₆): δ 167.5 (CO₂), 165.0 (C4), 143.9 (C5), 134.5 (C3), 130.6 (C2), 127.8 (C8), 127.0 (C10), 122.4 (C6), 116.8 (C9), 116.5 (C7). MS [EI, m/z (%)]: 206 (100), 160 (64), 147 (99), 119 (36). HRMS calcd for [C₁₀H₁₀N₂O₃ + H]⁺ 207.0764, found 207.0769. F T–IR (KBr) (cm^-1): 3388, 3308, 1706, 1308, 839.

S3. Refinement

All non-hydrogen atoms were refined anisotropically, C—H and amide hydrogen were placed in calculated positions, with distances C—H = 0.95 Å, N—H = 0.87 Å and O—H = 0.87 Å and U_iso(H) = 1.2 U_eq (C, N) or 1.5 U_eq (O). The H atoms of the amine group were refined but the N—H distances were restrained to 0.87 (2) Å [U_iso(H) = 1.2 U_eq(N)].

Computing details

Data collection: COLLECT (Nonius, 2001); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: PLATON (Spek, 2003).

Figures

	Fig. 1. A view of (I), showing 30% probability displacement ellipsoids (H atoms are draw as small spheres of arbritary radii).
	Fig. 2. Part of the crystal structure of (I), showing the formation of a hydrogen-bonded R^22(10) dimer. Dashed lines indicate hydrogen bonds. Atoms marked with (i) are the at the symmetry related position (-x + 1, -y + 1, -z + 1).
	Fig. 3. The packing of (I), showing the R^44(28) ring pattern. Dashed lines indicate hydrogen bonds. For the sake of clarity, H atoms not involved in the motifs shown have been omitted. [Symmetry codes: (ii) -x, y - 1/2, -z + 1/2; (iii) -x + 1, y - 1/2, -z + 3/2; (iv) x, y - 1, z.]
	Fig. 4. Part of the crystal structure of (I), showing the formation weak N—H···π and π···π interactions. For clarity, all H atoms not involved in the motifs shown have been omitted [Symmetry codes: (iii) -x + 1, y - 1/2, -z + 3/2; (v) -1 + x, 3/2 - y, -1/2 + z.]

(Z)-3-(2-aminophenylcarbamoyl)propenoic acid

Crystal data

C10H10N2O3	F(000) = 432
Mr = 206.2	Dx = 1.425 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2535 reflections
a = 7.3899 (2) Å	θ = 1–29°
b = 12.2135 (3) Å	µ = 0.11 mm^−1
c = 12.2633 (3) Å	T = 294 K
β = 119.726 (1)°	Prism, colourless
V = 961.19 (4) Å^3	0.25 × 0.25 × 0.1 mm
Z = 4

Data collection

Nonius KappaCCD area-detector diffractometer	1155 reflections with I > 2.5σ(I)
Radiation source: Enraf–Nonius FR590	Rint = 0.039
Graphite monochromator	θmax = 28.6°, θmin = 2.5°
Detector resolution: 9 pixels mm^-1	h = −9→9
φ and ω scans	k = −16→16
4773 measured reflections	l = −16→16
2418 independent reflections

Refinement

Refinement on F	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.051	H atoms treated by a mixture of independent and constrained refinement
S = 1.01	Method = Modified Sheldrick w = 1/[σ^2(F^2) + (0.04P)^2], where P = (max(Fo^2,0) + 2Fc^2)/3 (Sheldrick, 1997)
1155 reflections	(Δ/σ)max = 0.000165
142 parameters	Δρmax = 0.17 e Å^−3
2 restraints	Δρmin = −0.17 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
C1	0.0694 (3)	0.9421 (2)	0.2238 (2)	0.0631
C2	0.1320 (3)	0.82792 (19)	0.21902 (19)	0.0626
C3	0.2464 (3)	0.75461 (18)	0.30799 (19)	0.0566
C4	0.3461 (3)	0.76698 (16)	0.44500 (18)	0.0479
C5	0.5634 (3)	0.67199 (14)	0.64461 (16)	0.0421
C6	0.5469 (3)	0.57449 (15)	0.69851 (16)	0.0449
C7	0.6578 (3)	0.56406 (18)	0.82783 (18)	0.057
C8	0.7808 (3)	0.64865 (18)	0.9029 (2)	0.0633
C9	0.7967 (3)	0.74467 (17)	0.84874 (19)	0.0575
C10	0.6885 (3)	0.75622 (15)	0.71998 (18)	0.0491
H1	0.2094	0.9452	0.392	0.1064*
H2	0.0782	0.8031	0.1371	0.0719*
H3	0.2663	0.6861	0.2818	0.0655*
H4	0.4646	0.6245	0.4705	0.0569*
H7	0.6456	0.4975	0.8645	0.0697*
H8	0.8545	0.6406	0.9915	0.0728*
H9	0.8829	0.8021	0.9008	0.0643*
H10	0.7023	0.8206	0.6838	0.0573*
H61	0.316 (3)	0.5050 (17)	0.5507 (16)	0.0671*
H62	0.409 (3)	0.4385 (16)	0.6653 (18)	0.0687*
N4	0.4533 (2)	0.67995 (12)	0.51109 (13)	0.0474
N6	0.4266 (3)	0.48726 (14)	0.62196 (17)	0.0557
O1	0.1358 (2)	0.99089 (13)	0.33127 (15)	0.0797
O2	−0.0414 (3)	0.99077 (16)	0.12712 (16)	0.0937
O4	0.3304 (2)	0.85106 (12)	0.49678 (12)	0.0711

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0556 (12)	0.0661 (15)	0.0542 (14)	−0.0072 (11)	0.0170 (11)	0.0160 (12)
C2	0.0636 (12)	0.0744 (16)	0.0390 (12)	−0.0143 (12)	0.0172 (10)	−0.0011 (11)
C3	0.0666 (13)	0.0534 (13)	0.0449 (12)	−0.0047 (11)	0.0240 (11)	−0.0063 (10)
C4	0.0549 (11)	0.0432 (11)	0.0430 (11)	−0.0034 (9)	0.0222 (9)	−0.0036 (9)
C5	0.0471 (10)	0.0398 (10)	0.0399 (10)	0.0036 (8)	0.0218 (9)	−0.0006 (8)
C6	0.0513 (10)	0.0395 (10)	0.0478 (11)	0.0024 (9)	0.0276 (9)	−0.0007 (8)
C7	0.0703 (13)	0.0511 (12)	0.0524 (12)	0.0047 (11)	0.0327 (11)	0.0069 (10)
C8	0.0742 (14)	0.0642 (15)	0.0421 (11)	0.0112 (12)	0.0217 (10)	0.0035 (11)
C9	0.0591 (12)	0.0517 (13)	0.0479 (13)	0.0028 (10)	0.0160 (10)	−0.0073 (10)
C10	0.0542 (11)	0.0399 (11)	0.0499 (12)	−0.0002 (9)	0.0233 (10)	−0.0017 (9)
N4	0.0635 (10)	0.0367 (9)	0.0416 (9)	0.0011 (8)	0.0257 (8)	−0.0037 (7)
N6	0.0686 (11)	0.0415 (10)	0.0590 (12)	−0.0063 (9)	0.0331 (10)	−0.0004 (8)
O1	0.0946 (12)	0.0566 (10)	0.0640 (11)	0.0115 (8)	0.0210 (9)	0.0103 (8)
O2	0.0916 (12)	0.0978 (14)	0.0665 (11)	0.0065 (10)	0.0199 (10)	0.0353 (10)
O4	0.0936 (11)	0.0542 (9)	0.0460 (9)	0.0215 (8)	0.0197 (8)	−0.0042 (7)

Geometric parameters (Å, º)

C1—C2	1.479 (3)	C6—N6	1.407 (2)
C1—O1	1.301 (3)	C7—C8	1.383 (3)
C1—O2	1.211 (2)	C7—H7	0.954
C2—C3	1.339 (3)	C8—C9	1.381 (3)
C2—H2	0.929	C8—H8	0.948
C3—C4	1.470 (3)	C9—C10	1.379 (3)
C3—H3	0.933	C9—H9	0.949
C4—N4	1.333 (2)	C10—H10	0.932
C4—O4	1.243 (2)	H1—O1	0.872
C5—C6	1.396 (3)	H4—N4	0.869
C5—C10	1.386 (2)	H61—N6	0.879 (15)
C5—N4	1.425 (2)	H62—N6	0.849 (15)
C6—C7	1.383 (3)
C2—C1—O1	120.3 (2)	C6—C7—H7	118.5
C2—C1—O2	119.8 (2)	C8—C7—H7	120.5
O1—C1—O2	119.9 (2)	C7—C8—C9	119.90 (19)
C1—C2—C3	133.0 (2)	C7—C8—H8	120
C1—C2—H2	112.1	C9—C8—H8	120.1
C3—C2—H2	115	C8—C9—C10	119.90 (19)
C2—C3—C4	128.2 (2)	C8—C9—H9	119.5
C2—C3—H3	117.6	C10—C9—H9	120.6
C4—C3—H3	114.2	C5—C10—C9	120.29 (17)
C3—C4—N4	115.02 (17)	C5—C10—H10	120.1
C3—C4—O4	123.22 (18)	C9—C10—H10	119.6
N4—C4—O4	121.74 (17)	C5—N4—C4	125.55 (15)
C6—C5—C10	120.22 (17)	C5—N4—H4	116.3
C6—C5—N4	117.91 (16)	C4—N4—H4	118
C10—C5—N4	121.85 (16)	C6—N6—H61	116.5 (14)
C5—C6—C7	118.70 (17)	C6—N6—H62	110.8 (15)
C5—C6—N6	120.31 (17)	H61—N6—H62	116.1 (19)
C7—C6—N6	120.95 (18)	H1—O1—C1	109.5
C6—C7—C8	120.98 (19)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O4	0.87	1.62	2.492 (2)	174
N4—H4···N6^i	0.87	2.17	3.009 (3)	163
N6—H61···O2^ii	0.878 (19)	2.125 (19)	2.969 (3)	161.0 (19)
C7—H7···O4^iii	0.95	2.41	3.349 (3)	166
N6—H62···C9^iii	0.85 (2)	2.77 (2)	3.496 (3)	144.0 (17)

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x, y−1/2, −z+1/2; (iii) −x+1, y−1/2, −z+3/2.